IPAC2015 - List of Keywords (vacuum)

Paper	Title	Other Keywords	Page
MOBD1	Preliminary Design of the High-Luminosity LHC Beam Screen with Shielding	shielding, luminosity, cryogenics, impedance	60
	C. Garion, V. Baglin, R. Kersevan CERN, Geneva, Switzerland
	A new beam screen is needed in the High-Luminosity LHC (HL-LHC) final focusing magnets. Such an essential vacuum component, while operating in the range 40-60 K, has to ensure the vacuum performance and to prevent the beam-induced heating from reaching the cold bore which is at 1.9 K. In addition, they have to shield the cold mass from physics debris coming from the nearby beam collision points. To such purpose, energy absorbers made of tungsten alloy are installed onto the beam screen in the vacuum system. In this contribution, the proposed mechanical design is shown; it covers different thermomechanical aspects such as the behaviour during a magnet quench and the heat transfer from the tungsten absorbers to the cooling tubes. Assembly and manufacturing tolerances are also considered to evaluate the impact on the aperture. Results obtained with a short prototype assembly test are discussed.
	Slides MOBD1 [3.089 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOBD1
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWA006	Core-Halo Limit as an Indicator of High Intensity Beam Internal Dynamics	space-charge, emittance, linac, simulation	86
	P.A.P. Nghiem, N. Chauvin, N. Pichoff, D. Uriot, M. Valette CEA/DSM/IRFU, France
	The dynamics of high-intensity beams is mainly governed by their internal space charge forces. These forces induce emittance growth and halo generation. They contribute to shape the beam density profile. As a consequence, a careful analysis of this profile can help revealing the internal dynamics of the beam. This paper recalls the precise core-halo limit determination proposed earlier , then studies its behavior through a wide range of beam profiles and finally shows its relevance as an indicator of the limit separating the two specific space charge field regimes of the core and the halo. P. A. P. Nghiem et al., Appl. Phys. Lett. 104, 074109 (2014)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA006
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWA066	Simulation on Buildup of Electron Cloud in Rapid Cycling Synchrotron of China Spallation Neutron Source	electron, proton, simulation, neutron	275
	K.W. Li, L. Huang, Y.D. Liu, S. Wang IHEP, Beijing, People's Republic of China
	Funding: Work supported by National Natural Science Foundation of China (11275221) Electron cloud interaction with high energy positive beam are believed responsible for various undesirable effects such as vacuum degradation, collective beam instability and even beam loss in high power proton circular accelerator. An important uncertainty in predicting electron cloud instability lies in the detail processes on the generation and accumulation of the electron cloud. The simulation on the build-up of electron cloud is necessary to further studies on beam instability caused by electron cloud. China Spallation Neutron Source (CSNS) is the largest scientific project in building, whose accelerator complex includes two main parts: an H⁻ linac and a rapid cycling synchrotron (RCS). The RCS accumulates the 80 MeV proton beam and accelerates it to 1.6 GeV with a repetition rate 25 Hz. During the beam injection with lower energy, the emerging electron cloud may cause a serious instability and beam loss on the vacuum pipe. A simulation code has been developed to simulate the build-up, distribution and density of electron cloud in CSNS/RCS.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA066
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE026	Revision of the Impedance Model for the Interpretation of the Single Bunch Measurements at ALBA	impedance, undulator, simulation, storage-ring	330
	T.F.G. Günzel, U. Iriso ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	Recent measurements showed that the ALBA transverse impedance model was able to explain 65% of the measured single bunch vertical detuning. * This report shows the revision of the impedance model developed to match latest single bunch measurements performed to evaluate the total effective machine impedance and impedance of specific elements, like in-vacuum undulators or a recently installed pinger magnet. The model improvement includes a better bunch length parameterisation, re-calculation of several vacuum chamber elements with Gdfidl, and inclusion of elements neglected so far in the impedance budget. We also show and discuss the computation of the resistive wall impedance using ImpedanceWake2D. * T.Günzel, U.Iriso, F.Perez, E.Koukovini-Platia, G.Rumolo, "Analysis of the single bunch measurements at the ALBA Storage Ring", TUPRI052, proc. of IPAC14 (2014).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE026
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE027	Beam-based Impedance Characterization of the ALBA Pinger Magnet	impedance, simulation, injection, synchrotron	334
	U. Iriso, T.F.G. Günzel ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain H. Bartosik, E. Koukovini-Platia, G. Rumolo CERN, Geneva, Switzerland
	The ALBA pinger magnet consists on two short kickers (for horizontal and vertical planes) installed in a single Titanium coated ceramic vacuum chamber. Single bunch measurements in the vertical plane were performed in the ALBA Synchrotron Light Source before and after the pinger installation, and by comparing the Transverse Mode Coupling Instability (TMCI) thresholds for zero chromaticity, we infer the pinger impedance and compare it with the model predictions. We also perform measurements for negative chromaticities and results are reported in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE027
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE035	An Extended SPS Longitudinal Impedance Model	impedance, kicker, simulation, resonance	360
	J.V. Campelo, T. Argyropoulos, T. Bohl, F. Caspers, J. F. Esteban Müller, J.B. Ghini, A. Lasheen, D. Quartullo, B. Salvant, E.N. Shaposhnikova, C. Zannini CERN, Geneva, Switzerland
	Longitudinal multi-bunch instability in the CERN SPS with a very low intensity threshold is a serious limitation for the future doubling of bunch intensity required by Hi-Lumi LHC project. A complete and accurate impedance model is essential to understand the nature of this instability and to plan possible cures. This contribution describes in detail the current longitudinal impedance model of the SPS. Recently, the model was updated with new findings and includes now the impedance of accelerating cavities, kicker and septum magnets, beam position monitors, vacuum Flanges, shielded and unshielded pumping ports, electrostatic septa and resistive wall. Electromagnetic simulations and bench measurements were used to build the model. The contribution from each element is described and compared to the total machine impedance. Together with relevant beam measurements and simulations, the analysis of the different sources of impedance is used to identify the source of the longitudinal instability limiting the SPS performance so that the responsible elements can be acted upon.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE035
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE036	Longitudinal Impedance Characterization of the CERN SPS Vacuum Flanges	impedance, resonance, simulation, damping	363
	J.V. Campelo CERN, Geneva, Switzerland
	This contribution describes the thorough studies carried out to characterize the longitudinal impedance of the CERN SPS vacuum flanges, which are believed to be the main source of LHC beam instability. Around 500 high-impedance flanges of 8 different types have been identified. Three factors play an important role in the characterization of these flanges: the type of vacuum chambers that the flange interconnects, whether or not both sides are electrically isolated (by means of an enamel coating) and, finally, the presence of damping resistors which damp high-Q resonances. Not only, full-wave electromagnetic field simulations, but also RF measurements have been used to evaluate the impedance of these elements. The R/Q of the relevant resonances was measured using the well-known bead-pull technique. In particular, a subset of around 150 flanges has been found to be the source of a high-impedance resonance at 1.4 GHz, also observed in beam measurements. Guidelines on how to reduce the impedance of these elements are also presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE036
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE037	Study and Comparison of Mode Damping Strategies for the UA9 Cherenkov Detector Tank	damping, cavity, detector, resonance	366
	A. Danisi, F. Caspers, R. Losito, A. Masi, B. Salvant, C. Vollinger CERN, Geneva, Switzerland T. Demma, P. Lepercq LAL, Orsay, France
	In the framework of the UA9 experiment, the Cherenkov detector is useful to measure the amount of particles deflected by a bent crystal, proving the crystal collimation principle. The tank used to host this device is taken as a case study for an in-depth analysis of different damping strategies for electromagnetic modes which otherwise would give rise to important beam-coupling impedance contributions. Such strategies involve the use of ferrite, damping resistors and a mode-coupler, a solution which intercepts the modes inside the cavity but damps the related power outside the vacuum tank (potentially avoiding heating). Such solutions are discussed through experimental measurements and the relative quality factor is taken as a figure of merit.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE037
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE043	Design and Optimization of Electrostatic Deflectors for ELENA	focusing, antiproton, alignment, simulation	382
	D. Barna University of Tokyo, Tokyo, Japan W. Bartmann, M.A. Fraser, R. Ostojić CERN, Geneva, Switzerland
	The ELENA ring will decelerate the antiprotons ejected from the Antiproton Decelerator (AD) at 5.3 MeV down to 100 keV kinetic energy. The slow antiprotons will be delivered to experiments using electrostatic beamlines, consisting of quadrupoles, correctors and deflectors. An extensive simulation study was carried out to find solutions to minimize the aberrations of the deflectors. These solutions will be presented together with the actual design of these devices.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE043
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE045	Fixed Points in Presence of Space Charge in Circular Particle Accelerators	space-charge, simulation, extraction, resonance	389
	M. Giovannozzi, S.S. Gilardoni, A. Huschauer CERN, Geneva, Switzerland S. Machida, C.R. Prior, S.L. Sheehy STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
	Recent measurements performed in the framework of the multi-turn extraction (MTE) studies showed a dependence of the position of beamlets obtained by crossing a stable transverse resonance on the total beam intensity. This novel observation has triggered a number of studies aiming at understanding the source of the observed effect. In this paper the results of numerical simulations performed in different conditions are discussed in detail.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE045
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE049	Benchmarking the CERN-SPS Transverse Impedance Model with Measured Headtail Growth Rates	impedance, simulation, kicker, optics	402
	C. Zannini, H. Bartosik, G. Iadarola, G. Rumolo, B. Salvant CERN, Geneva, Switzerland
	The latest SPS transverse impedance model includes kicker magnets, wall impedance, transition pieces (e.g. flanges and vacuum chamber discontinuities), beam position monitors and RF cavities. The model has already been successfully benchmarked against coherent tune shift and transverse mode coupling instability measurements. In this paper we present measurements of the headtail growth rates for a wide range of negative chromaticities and for two different configurations of machine optics (nominal and low gamma transition). The measurement results are compared with HEADTAIL simulations using the wake fields obtained from the SPS transverse impedance model.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE049
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE050	Transverse Impedance Model of the CERN-PSB	impedance, space-charge, kicker, simulation	406
	C. Zannini, G. Iadarola, K.S.B. Li, T.L. Rijoff, G. Rumolo CERN, Geneva, Switzerland B. Jones STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom T.L. Rijoff TU Darmstadt, Darmstadt, Germany
	In the framework of the PS-Booster upgrade project an accurate impedance model is needed in order to determine the effect on the beam stability and assess the impact of the new devices before installation in the machine. This paper describes the PSB impedance model which includes resistive wall, indirect space charge, flanges, step transitions, ejection kicker including cables, injection kickers and cavities. Each impedance contribution has been computed for different energies in the PSB cycle. Measurements of the coherent tune shifts have been performed and compared to calculations based on the impedance model.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE050
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE064	Beam Impedance Optimization of the TOTEM Roman Pots	impedance, detector, simulation, cavity	452
	N. Minafra CERN, Geneva, Switzerland
	The TOTEM experiment has been designed to measure the total proton-proton cross section and to study elastic and diffractive scattering at the LHC energy. The measurement requires detecting protons at distances as small as 1 mm from the beam center: TOTEM uses Roman Pots (RP), special beam pipe insertions, to move silicon detectors close to the beams to detect particles very near the beam axis. In the first period of running of the LHC no problems were detected with retracted Roman Pots and during insertions in special runs; however, during close insertions to highest intensity beam, impedance heating has been observed. After the LS1 the LHC beam current will increase and the equipment that can interact with the beam needed to be optimized. A new RP, optimized to minimize the beam coupling, has been designed with the help of CST Particle Studio; a prototype has been used to test the simulation results in the laboratory with wire and probe measurements. Furthermore, in both the old and the new RPs, new ferrites have been installed. The new ferrite material has a higher Curie temperature than the one used before LS1 and a thermal treatment at 1000°C has been applied to reduce the out-gassing.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE064
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE070	Reduction of Electron Cloud in Particle Accelerator Beampipes Studied by RF Multipacting	electron, injection, detector, network	472
	R. Leber, F. Caspers, P. Costa Pinto, M. Taborelli CERN, Geneva, Switzerland
	For a given beam structure, chamber geometry and magnetic field configuration, the electron cloud (EC) intensity depends on the Secondary Electron Yield (SEY) of the beam pipe. The reduction of the EC density as a function of machine operation time (scrubbing) is attributed to the growth of a low SEY carbon film induced by electron bombardment. In this paper, we study the time evolution of the conditioning of stainless steel beam pipes in a laboratory setup. The EC or multipacting is induced by Radio-Frequency (RF) fields in a coaxial resonator under vacuum. Strip detectors are used to monitor the current of the EC. Induced pressure rise is simultaneously detected. The multipacting intensity shows a linear dependence on the positive DC bias voltage up to 1000 V, applied to the central electrode. An accelerated conditioning is observed for the applied bias voltage. The SEY of samples exposed to the EC is measured and the surface composition is monitored by X-ray Photoelectron Spectroscopy. The measured SEY, surface composition and multipacting behaviour are well correlated. The injection of acetylene and dodecane during multipacting proved to be ineffective in the conditioning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE070
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA005	Non-invasive Beam Profile Monitoring	detector, operation, ion, proton	537
	C.P. Welsch, T. Cybulski, A. Jeff, V. Tzoganis, H.D. Zhang Cockcroft Institute, Warrington, Cheshire, United Kingdom T. Cybulski, A. Jeff, V. Tzoganis, C.P. Welsch, H.D. Zhang The University of Liverpool, Liverpool, United Kingdom A. Jeff CERN, Geneva, Switzerland V. Tzoganis RIKEN, Saitama, Japan
	Funding: Work supported by the Helmholtz Association under contract VH-NG-328, the EU under contracts 215080 and 289485, as well as the STFC Cockcroft core grant No. ST/G008248/1. State-of-the-art high energy and high intensity accelerators require new approaches to transverse beam profile monitoring as many established techniques will no longer work due to the high power stored in the beam. In addition, many accelerator applications such as ion beam cancer therapy or material irradiation would benefit significantly from the availability of non-invasive beam profile monitors. Research in the QUASAR Group has focused on this area over the past 5 years. Two different approaches were successfully developed: Firstly, a supersonic gas jet-based monitor was designed and commissioned. It enables the detection of the 2-dimensional transverse beam profile of essentially any charged particle beam with negligible disturbance of the primary beam and accelerator vacuum. Secondly, a monitor based on the Silicon strip VELO detector, originally developed for the LHCb experiment, was tested as an online beam monitor at the Clatterbridge Cancer Center in the UK. The design of both monitors is presented in this contribution. Results from measurements are discussed and complemented by numerical studies into the performance limits of either technique.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA005
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA008	Simulation of Gas-Scattering Lifetime using Position- and Species-Dependent Pressure and Aperture Profiles	scattering, simulation, storage-ring, photon	546
	M. Borland, J.A. Carter, H. Cease, B.K. Stillwell ANL, Argonne, Ilinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. When computing gas-scattering lifetime for storage rings, it is common to use the average pressure, even though it is known that the pressure varies with location in the ring and varies differently for different gas species. In addition, other simplifications are commonly made, such as assuming that the apertures in the horizontal and vertical planes are independent and assuming that the momentum acceptance can be characterized by a single value. In this paper, we describe computation of the elastic- and bremsstrahlung-scattering lifetimes that includes species-specific gas pressure profiles computed with VACCALC and MOLFLOW. In addition, the computations make use of the detailed shape of the dynamic acceptance and the position-dependent momentum acceptance. Comparisons are made to simpler methods for the Advanced Photon Source storage ring and the multi-bend achromat upgrade lattice.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA008
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA027	Electron Cloud Measurements in Fermilab Main Injector and Recycler	electron, proton, injection, operation	604
	J.S. Eldred Indiana University, Bloomington, Indiana, USA M. Backfish, J.S. Eldred, C.-Y. Tan, R.M. Zwaska Fermilab, Batavia, Illinois, USA
	This conference paper presents a series of electron cloud measurements in the Fermilab Main Injector and Recycler. A new instability was observed in the Recycler in July 2014 that generates a fast transverse excitation in the first high intensity batch to be injected. Microwave measurements of electron cloud in the Recycler show a corresponding dependence on the batch injection pattern. These electron cloud measurements are compared to those made with a retarding field analyzer (RFA) installed in a field-free region of the Recycler in November. RFAs are also used in the Main Injector to evaluate the performance of beampipe coatings for the mitigation of electron cloud. Contamination from an unexpected vacuum leak revealed a potential vulnerability in the amorphous carbon beampipe coating. The diamond-like carbon coating, in contrast, reduced the electron cloud signal to 1\% of that measured in uncoated stainless steel beampipe.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA027
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA033	Modeling Electron Emission and Surface Effects from Diamond Cathodes	electron, simulation, cathode, scattering	620
	D.A. Dimitrov, J.R. Cary, D.N. Smithe, C.D. Zhou Tech-X, Boulder, Colorado, USA I. Ben-Zvi, T. Rao, J. Smedley, E. Wang BNL, Upton, Long Island, New York, USA
	Funding: We are grateful to the U.S. DoE Office of Basic Energy Sciences for supporting this work under grants DE-SC0006246 and DE-SC0007577. We developed modeling capabilities, within the Vorpal particle-in-cell code, for three-dimensional (3D) simulations of surface effects and electron emission from semiconductor photocathodes. They include calculation of emission probabilities using general, piece-wise continuous, space-time dependent surface potentials, effective mass and band bending field effects. We applied these models, in combination with previously implemented capabilities for modeling charge generation and transport in diamond, to investigate the emission dependence on applied electric field in the range from approximately 2 to 17 MV/m along the [100] direction. The simulation results were compared to experimental data when using different emission models, band bending effects, and surface-dependent electron affinity. Simulations using surface patches with different levels of hydrogenation lead to the closest agreement with the experimental data.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA033
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA039	Secondary Electron Yield Measurement and Electron Cloud Simulation at Fermilab	electron, simulation, proton, dipole	629
	Y. Ji IIT, Chicago, Illinois, USA L.K. Spentzouris Illinois Institute of Technology, Chicago, Illinois, USA R.M. Zwaska Fermilab, Batavia, Illinois, USA
	Funding: This work was funded by the National Science Foundation under the grant no. 1205811. Fermilab Main Injector is upgrading the accelerator to double the beam intensity from 24·10¹² protons to 48·10¹² protons, which brings the accelerator into a regime where electron cloud effects may limit the accelerator performance. In fact, an instability that could be caused by electron cloud effects has already been observed in the Recycler. Secondary Electron Yield (SEY) is an important property of the vacuum chamber material that has great influence on the process of building up free electrons. The Main Injector of the Fermilab accelerator complex offers the opportunity to measure SEY and conditioning effects in the environment of a running accelerator, since samples of these materials are located at the beampipe wall. The SEY of stainless steel (SS316L) and TiN coated SS316L in the proximity of the proton beam were measured and compared. A series of simulation studies of electron cloud build up were done for the Main Injector and Recycler using the code POSINST. Parametric studies were done to determine the maximum electron density vs. peak SEY at different beam intensities in the Fermilab Main Injector. Threshold simulations of electron cloud density verus SEY were extended from Main Injector to include the Recycler Ring. It was found that the electron cloud density around the beam depends on bunch location within the bunch train.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA039
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA060	Impedance Measurement for the SPEAR3 Storage Ring	impedance, lattice, storage-ring, damping	694
	X. Huang, J.J. Sebek SLAC, Menlo Park, California, USA
	We studied the transverse impedance of the SPEAR3 storage ring with tune shift vs. beam intensity, head-tail instability and transverse mode coupling instability measurements. By taking measurements under different machine conditions, we probed the frequency dependence of the impedance, from which an impedance model was built. This model is consistent with instability measurements and previous bunch lengthening results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA060
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMN010	Non-linear Magnetic Inserts for the Integrable Optics Test Accelerator	alignment, optics, dipole, quadrupole	724
	F.H. O'Shea, R.B. Agustsson, Y.C. Chen, E. Spranza RadiaBeam, Santa Monica, California, USA D.W. Martin, J.D. McNevin RadiaBeam Systems, Santa Monica, California, USA
	We present here a status update of the manufacture and magnetic measurements of the non-linear inserts for the Integrable Optics Test Accelerator. RadiaBeam Technologies is designing the 2-meter structure from magnetic field specifications, including pole design, measurement systems and alignment fiducialization. Herein, we will describe the current state of the project.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMN010
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMN021	NSLS-II Storage Ring BPM Button Development	impedance, simulation, multipole, storage-ring	748
	A. Blednykh, B. Bacha, G. Bassi, W.X. Cheng, C. Hetzel, B.N. Kosciuk, D. Padrazo, O. Singh BNL, Upton, Long Island, New York, USA
	Funding: Work supported by DOE contract DE-AC02-98CH10886 The NSLS-II BPM Button design and its development process have been described. Subjects discussed include BPM Button impedance optimization, design and construction, production, BPM Button selection and a first temperature measurements at 200mA average current within 1200 bunches.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMN021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMN025	Local Impedance Estimation of NSLS-II Storage Ring with Bumped Orbit	impedance, closed-orbit, wiggler, damping	754
	J. Choi, G. Bassi, A. Blednykh, Y. Hidaka BNL, Upton, Long Island, New York, USA
	Funding: DOE contract No: DE-AC02- 98CH10886 As the newly constructed 3rd generation light source, NSLS-II is expected to provide the synchrotron radiation of ultra high brightness and flux with advanced insertion devices. To minimize the beam emittance, damping wigglers are used and the small aperture is located at the straight section with the damping wiggler and the corresponding vacuum camber is NEG coated. We used the local bump method to find the effect on the beam from the narrow aperture and the paper shows the results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMN025
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPHA008	Investigation of Beam Halo Using In Vacuum Diamond Sensor at ATF2	electron, pick-up, controls, laser	791
	S. Liu, P. Bambade, F. Bogard, P. Cornebise, V. Kubytskyi, C. Sylvia LAL, Orsay, France A. Faus-Golfe, N. Fuster-Martínez IFIC, Valencia, Spain T. Tauchi, N. Terunuma KEK, Ibaraki, Japan T. Tauchi, N. Terunuma Sokendai, Ibaraki, Japan
	Funding: Chinese Scholarship Council, CNRS and P2IO LABEX Beam halo transverse distribution measurements are of great importance for the understanding of background sources of the nano-meter beam size monitor at the interaction point (IPBSM) of ATF2. One of the most critical issues for the beam halo measurement is to reach high dynamic range. Two in vacuum diamond sensor beam halo scanners (DSv) with four strips each have been developed for the investigation of beam halo transverse distributions at ATF2. The first DSv was installed for horizontal beam halo scanning after the interaction point (IP) of ATF2, in Nov. 2014. It aims to measure the beam halo distribution with large dynamic range (~10⁶), and investigate the possibility of probing the Compton recoil electrons produced in the interaction with the IPBSM laser beams. Studies to characterize the DS performance and measurements of horizontal beam halo performed in Nov.-Dec. 2014 are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA008
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPHA013	Superconducting Radio Frequency Cavity Degradation Due to Errant Beam	cavity, ion, ion-source, linac	805
	C.C. Peters, D. Curry, G.D. Johns ORNL RAD, Oak Ridge, Tennessee, USA A.V. Aleksandrov, W. Blokland, M.T. Crofford, C. Deibele, G.W. Dodson, J. Galambos, T.A. Justice, S.-H. Kim, T.A. Pelaia II, M.A. Plum, A.P. Shishlo ORNL, Oak Ridge, Tennessee, USA
	Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05- 00OR22725 for the U.S. Department of Energy. In 2009, the Superconducting Radio Frequency (SRF) cavities at the Spallation Neutron Source (SNS) began to experience significant operational degradation [1]. The source of the degradation was found to be repeated striking of cavity surfaces with errant beam pulses. The Machine Protection System (MPS) was designed to turn the beam off during a fault condition in less than 20 μseconds [2] as these errant beam pulses were not unexpected. Unfortunately an improperly operating MPS was not turning off the beam within the designed 20 μseconds, and the SRF cavities were being damaged. The MPS issues were corrected, and the SRF performance was restored with cavity thermal cycling and RF processing. However, the SRF cavity performance has continued to degrade, though at a reduced rate compared to 2009. This paper will detail further study of errant beam frequency, amount lost per event, causes, and the corrective actions imposed since the initial event.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA013
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPHA049	Evolution of Diagnostics and Services of the DAΦNE Beam Test Facility	detector, linac, controls, diagnostics	904
	L.G. Foggetta, B. Buonomo INFN/LNF, Frascati (Roma), Italy P. Valente INFN-Roma, Roma, Italy
	The DAΦNE Beam Test Facility (BTF) is operational in Frascati since 2003. In the last years the beam diagnostics tools have been completely renewed and the services for users have been largely improved. We describe here the new transverse beam diagnostics based on new GEM TPC detectors and Timepix/FitPix, the new BTF network layout, the renewed DAQ system including the BCM detectors, the data caching system based on MEMCached and the integration of the new sub-systems in the new data-logging. All other services, such as the environmental monitoring system, vacuum system, payload remote handling, and gas distribution have been also improved.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA049
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPHA051	Scintillating Fibers used as Profile Monitors for the CNAO HEBT Lines	detector, proton, ion, extraction	910
	E. Rojatti UniPV, Pavia, Italy J. Bosser, M. Haguenauer, P. Poilleux CERN, Geneva, Switzerland J. Bosser, G.M.A. Calvi, L. Lanzavecchia, A. Parravicini, M. Pullia, C. Viviani CNAO Foundation, Milan, Italy M. Caldara University of Bergamo, Bergamo, Italy
	The CNAO (Centro Nazionale di Adroterapia Oncologica) Foundation is the first Italian center for deep hadrontherapy with Protons and Carbon Ions. Several beam monitors exploiting the scintillation process have been designed to check the beam quality in the extraction lines, in order to guarantee patients safety. The SFH (Scintillating Fibers Harp), the QPM (Qualification Profile Monitor), and the SFP (Scintillating Fibers plus Photodiodes) are made up by two orthogonal scintillating fibers harps with not dead area for the horizontal and the vertical beam profiles measurement. The QPM and the SFH are both installed on the beam line and they use a CCD camera for the signal acquisition. The SFP is a SFH upgrade project aimed to replace the camera with two Photodiodes arrays coupled to the fibers in vacuum. The WD (Watch Dog) detector, not already installed, has been designed to check the beam position through the intensity of the beam tails. It uses two couples of scintillating fibers displaced transversally to the beam direction, coupled to four APDs (Avalanche Photodiodes). This work describes the beam detectors, their achieved performances and the most recent beam measurements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA051
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPHA054	Interaction Point Orbit Feedback System at SuperKEKB	feedback, luminosity, quadrupole, simulation	921
	Y. Funakoshi, H. Fukuma, T. Kawamoto, M. Masuzawa, T. Oki, S. Uehara, H. Yamaoka KEK, Ibaraki, Japan S.D. Anderson, S.M. Gierman, M. Kosovsky, J.T. Seeman, C.M. Spencer, M.K. Sullivan, O. Turgut, U. Wienands SLAC, Menlo Park, California, USA P. Bambade, D. El Khechen, D. Jehanno, V. Kubytskyi, C. Rimbault LAL, Orsay, France
	In order to maintain an optimum beam collision condition in a double ring collider such as SuperKEKB it is essential to have an orbit feedback system at the interaction point (IP). We have designed such a system based on experiences at KEKB and PEP-II. For the vertical offset and crossing angle, we will rely on the system based on the beam orbit measurement similar to that used at KEKB. For the horizontal offset, however, we will utilize the dithering system which was successfully used at PEP-II, because the horizontal beam-beam kick is very weak with the "nano-beam scheme". Some hardware devices have been already fabricated and others are in preparation. The present status of the development is reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA054
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPTY011	Operation Experience of p-Carbon Polarimeter in RHIC	target, polarization, detector, operation	956
	H. Huang, E.C. Aschenauer, G. Atoian, A. Bazilevsky, O. Eyser, D. Kalinkin, J. Kewisch, Y. Makdisi, S. Nemesure, A. Poblaguev, W.B. Schmidke, D. Smirnov, D. Steski, K. Yip, A. Zelenski BNL, Upton, Long Island, New York, USA I.G. Alekseev, D. Svirida ITEP, Moscow, Russia
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The spin physics program in Relativistic Heavy Ion Collider (RHIC) requires fast polarimeter to monitor the polarization evolution on the ramp and during stores. Over past decade, the polarimeter has evolved greatly to improve its performance. These include dual chamber design, monitoring camera, Si detector selection (and orientation), target quality control, and target frame modification. The preamp boards have been modified to deal with the high rate problem, too. The ultra thin carbon target lifetime is a concern. Simulations have been carried out on the target interaction with beam. Modification has also been done on the frame design. Extra caution has been put on RF shielding to deal with the pickup noises from the nearby stochastic cooling kickers. This paper summarizes the recent operation performance of this delicate device.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY011
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPTY030	Capacitive Linear-Cut Beam Position Monitor Design for Ion Synchrotron at KHIMA Project	synchrotron, target, operation, proton	998
	J.G. Hwang, C.H. Kim, S.H. Nam, S.Y. Noh KIRAMS/KHIMA, Seoul, Republic of Korea G. Hahn, W.T. Hwang, T.K. Yang KIRAMS, Seoul, Republic of Korea E.-S. Kim Kyungpook National University, Daegu, Republic of Korea
	The KHIMA (Korea Heavy Ion Medical Accelerator) project is launched to construct the carbon and proton beam base ion therapy machine. It, which consists of the injector with RFQ and IH-DTL linacs, medium beam transport line, synchrotron, and high energy beam transport line, will be provided the carbon beam up to 430 MeV/u and proton beam up to 230 MeV for cancer therapy. The high precision beam position monitor is required to match and control the beam trajectory for the beam injection and closed orbit in synchrotron. It was also used for measuring the beta-function, tune, and chromaticity. Since the bunch length at heavy ion synchrotron is relatively long, a few meters, a box-like device with long plates of typically 20 cm is used to enhance the signal strength and to get a precise linear dependence with respect to the beam displacement. In this presentation, we show the electromagnetic design of the electrode and surroundings to satisfy the resolution of 100 um, the criteria for mechanical aspect to satisfy the position accuracy of 200 um, the measurement result of position accuracy by using the wire test-bench, and the beam-test results with long (~ 1.6 us) electron beam in PAL.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY030
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPTY033	Fast Kicker	kicker, impedance, simulation, magnet-design	1001
	V.V. Gambaryan, A.A. Starostenko BINP SB RAS, Novosibirsk, Russia
	Pulsed deflecting magnet project was worked out in BINP. The kicker design task is: impulsive force value is 1 mT*m, pulse edge is 5 ns, and impulse duration is about 200 ns. The unconventional approach to kicker design was offered. The possibility for set of wires using instead of plates using is considered. This approach allows us to reduce the effective plate surface. In this case we can decrease effects related to induced charges and currents. In the result of modelling optimal construction was developed. It includes 6 wires. The magnet aperture is about 5 cm. Calculated field rise time (about 1.5 ns) satisfies the conditions. Induced current effect reducing idea was confirmed. For configuration with 3 wires pair (with cross section of 2 mm) induced current in one wire is about 10% and in the wall is about 40%. However for design with plates current is about 40% and 20% respectively. Obtained magnet construction allows controlling of high field homogeneity by changing currents magnitudes in wires. In general we demonstrated the method of field optimization. Optimal kicker design was obtained. Wires using idea was substantiated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY033
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPTY036	Radiation of a Bunch Moving in the Presence of a Bounded Planar Wire Structure	radiation, diagnostics, electronics, electromagnetic-fields	1007
	V.V. Vorobev, S.N. Galyamin, A.A. Grigoreva, A.V. Tyukhtin Saint-Petersburg State University, Saint-Petersburg, Russia
	Three-dimensional* and planar periodic structures can be used for non-destructive diagnostics of charged particle bunches. Here we consider the semi-infinite planar structure comprised of thin conducting parallel wires. If the period of the structure is much less than the typical wavelength of the electromagnetic field, then the structure's influence can be described with help of the averaged boundary conditions. We study radiation of a charged particle bunch with small transversal size and arbitrary longitudinal one in two cases: (i) the bunch moves orthogonally to the grid at some distance from the edge and (ii) it moves along the edge of the grid. The problems are solved analytically. In both cases the bunch generates a surface wave which contains the information about the size of the bunch. The shape of the surface waves is similar to the radiation generated in the presence of 3D periodical wire structures, however planar structure is simpler for use in accelerating system. Some typical numerical results for bunches of various shapes are given. * V.V. Vorobev et al., Phys. Rev. Let., 108, 184801 (2012); A.V. Tyukhtin et al., Phys. Rev. ST AB (in press). * M.I. Kontorovich et al., Electrodynamics of Grid Structures (Moscow, 1987).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY036
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPTY063	The Flexible Customized Supervisor and Control System for Utility in TPS	controls, network, operation, monitoring	1085
	C.S. Chen, W.S. Chan, J.-C. Chang, Y.C. Chang, Y.-C. Chung, C.W. Hsu, C.Y. Liu, Z.-D. Tsai NSRRC, Hsinchu, Taiwan
	In order to maintain and operate a synchrotron radiation light source well requires quite a few efforts. All parts of the big machine, including vacuum system, all kinds of magnets, RF facility, cryogenic equipments, radiation security, optic devices and utility equipment must cooperate in harmony to provide high quality light. Any one of the above system contains lots of analog or digital signal transmission, not to mention the vast range of utility. Numbers of programmable automation controllers (PACs) are applied in utility system in TPS to ensure the utility operates normally. In addition to the high reliability and distribution, the flexible programmability of PAC is the most critical feature in this project. A well-designed program, Archive Viewer, provides a platform for showing these big data from all distributed systems. The architecture of the server system for utility is described in this paper as well.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY063
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWI006	Development of a Supersonic Gas-jet Monitor to Measure Beam Profile Non-destructively	ion, electron, storage-ring, experiment	1157
	H.D. Zhang, A. Jeff, V. Tzoganis, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom A. Jeff CERN, Geneva, Switzerland A. Jeff, V. Tzoganis, C.P. Welsch, H.D. Zhang The University of Liverpool, Liverpool, United Kingdom V. Tzoganis RIKEN, Saitama, Japan
	Funding: This project is supported by Helmholtz Association(VH-NG-328), EU’s 7th Framework Program for research, technological development and demonstration( 215080) and STFC Cockcroft core grant(ST/G008248/1). The measurement of the transverse beam profile is a great challenge for high intensity, high brightness and high power particle beams due to their destructive power. Current non-destructive methods such as residual gas monitors and beam induced fluorescence monitors either require a rather long integration time or residual gas pressures in the order of 10^-7 mbar to make meaningful measurements. A supersonic gas-jet beam profile monitor has been developed by QUASAR group at the Cockcroft Institute, UK and promises significant improvements over these established techniques. In this monitor, a supersonic gas curtain is generated that crosses the beam to be analyzed under an angle of 45°. When both beams interact, ionization of the gas jet particles occurs and these ions are then accelerated by an electrostatic extraction field towards a Micro Channel Plate (MCP). Beam images are then obtained via a phosphor screen-CCD camera combination. In this contribution, we discuss the monitor design and present beam profile measurements of a 5 keV electron beam. These are complemented by results from measurements using a pulsed valve to study the gas jet dynamics.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI006
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWI009	A Multi-pinhole Faraday Cup Device for Measurement of Discrete Charge Distribution of Heavy and Light Ions	ion, electron, diagnostics, experiment	1160
	P.K. Roy, S. Dwaraknath, F.U. Naab, S. Taller, O.F. Toader, G. Was NERS-UM, Ann Arbor, Michigan, USA
	It is a difficult task to identify the beam density distribution profile over discrete areas using a standard Faraday cup, as the measurements are provided for the full aperture geometry of the instrument. Ideally, the intensity of the scintillating material would provide a correlation to the beam density, but the low photon efficiency, damage to the scintillator, and camera resolution all limit the practicality of using this system for assessing the spatial resolution of an ion beam. A beam profile monitor (BPM) device has the ability to provide a partial or discrete distribution of an integrated beam profile. The BPM, however, does not discriminate between ions and electrons, the latter of which can be problematic for assessing the full beam profile. To provide a better description of the beam density in spatial dimensions, a multi-pinhole Faraday cup (MPFC) has been designed, developed, and applied to the measurement of energetic ions. This device uses an array of millimeter sized Faraday cups arranged in a grid to measure the current of the beam at discrete locations. This report presents the design of the device, and its performance with ion beams.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI009
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWI010	Design and Development of a Beam Stablity Mechanical Motion System Diagnostic for the APS MBA Upgrade	detector, insertion, insertion-device, ground-motion	1164
	R.M. Lill, G. Decker, N. Sereno, B.X. Yang ANL, Argonne, Ilinois, USA
	Funding: Results shown in this report result from work performed at Argonne National Laboratory operated by UChicago Argonne, LLC, for the U.S. Department of Energy under contract DE-AC02-06CH11357. The Advanced Photon Source (APS) is currently in the conceptual design phase for the MBA lattice upgrade. In order to achieve long-term beam stability goals, a Mechanical Motion System (MMS) has been designed to monitor critical in-tunnel beam position monitoring devices. The mechanical motion generated from changes in chamber cooling water temperature, tunnel air temperature, beam current and undulator gap positon causes erroneous changes in beam position measurements causing drift in the X-ray beam position. The MMS has been prototyped and presently provides critical information on the vacuum chamber and BPM support systems. We report on first results of the prototype system installed in the APS storage ring.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI010
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWI012	Conceptual Design and Analysis of a Storage Ring Beam Position Monitor for the APS Upgrade	operation, simulation, alignment, impedance	1170
	B.K. Stillwell, R.M. Lill, R.R. Lindberg, M.M. O'Neill, B.G. Rocke, X. Sun ANL, Argonne, Ilinois, USA A. Blednykh BNL, Upton, Long Island, New York, USA
	Funding: Created by UChicago Argonne, LLC, operator of Argonne National Laboratory, a U.S. Department of Energy Office of Science laboratory operated under Contract No. DE-AC02-06CH11357. A conceptual design has been developed for a radio frequency (rf) pickup-type beam position monitor (BPM) for use in a multi-bend achromat (MBA) storage ring under consideration by the APS Upgrade project (APS-U). Beam feedback systems are expected to require fourteen rf BPMs per sector with exceptional sensitivity and mechanical stability. Simultaneously, BPM insertion length must be minimized to allow lattice designers the greatest freedom in selecting magnet lengths and locations. Envisioned is a conventional four probe arrangement integrated inside of a pair of rf-shielded bellows for mechanical isolation. Basic aspects of the design are presented along with the results of analyses which establish expected mechanical, electronic, and beam physics-related performance measures.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI012
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUXC2	Engineering Challenges of Future Light Sources	storage-ring, feedback, emittance, synchrotron	1308
	R.T. Neuenschwander, L. Liu, S.R. Marques, A.R.D. Rodrigues, R.M. Seraphim LNLS, Campinas, Brazil
	We review some of the present engineering challenges associated with the design and construction of ultra-low emittance storage rings, the 4th generation storage rings (4GSR). The field is experiencing a growing interest since MAX-IV, followed by Sirius, started to build storage rings based on multi-bend-achromat (MBA) lattices. It was the recent progress in accelerator technology that allowed these facilities to base their designs on this kind of lattice. Although the challenges are starting to be overcome, many issues are still open and a lot of R&D is required until the 4GSR achieve optimal performance.
	Slides TUXC2 [7.022 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUXC2
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUAB2	First Collective Effects Measurements in NSLS-II with ID's	impedance, lattice, quadrupole, storage-ring	1332
	A. Blednykh, B. Bacha, G. Bassi, W.X. Cheng, J. Choi, Y. Hidaka, Y. Li, B. Podobedov, T.V. Shaftan, V. Smalyuk, T. Tanabe, G.M. Wang, F.J. Willeke, L.-H. Yu BNL, Upton, Long Island, New York, USA
	Funding: Work supported by DOE contract DE-AC02-98CH10886. As another important milestone towards the final goal to store an average current of 500mA, the average current of 200mA, distributed within ~1000 bunches, was recently achieved in the NSLS-II storage ring after the installation of three Damping Wigglers and four In-Vacuum Undulators. First measurements of the collective effects and instability thresholds, both in single- and multi-bunch mode, are discussed.
	Slides TUAB2 [2.691 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUAB2
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUAD1	Magnet Design and Control of Field Quality for TPS Booster and Storage Rings	quadrupole, dipole, sextupole, multipole	1370
	J.C. Jan, C.H. Chang, C.-T. Chen, H.H. Chen, Y.L. Chu, M.-H. Huang, C.-S. Hwang, C.Y. Kuo, F.-Y. Lin, G.-H. Luo, I.C. Sheng, C.S. Yang, Y.T. Yu NSRRC, Hsinchu, Taiwan
	High-quality and very demanding magnets were designed, fabricated, field quality controlled and installed in the Taiwan Photon Source (TPS). The Storage Ring (SR) lattice is based on double-bend achromat structure with 1.6 nm-rad emittance and slight dispersion in straight sections. The fabrication and field measurement of these magnets were completed in Oct. 2013. The first synchrotron light from TPS storage ring, without applying any corrector at 3 GeV, was observed on Dec. 31, 2014. It indicates that the profile precision and field quality of magnets, and girders alignment reach world class standard. The integral multipoles components of the 240 SR quadrupole and 168 SR sextupole magnets conform to strict specifications. The maximum offset of measured mechanical center in magnets is better than 0.01 mm after feet shimming. The magnetic center offset of the magnets is within 0.02 mm inspected by rotating-coil method. The magnets’ field quality of booster’s pure quadrupole and combined-function quadrupole were accepted according to the errors specifications from beam dynamics and also in the beam commissioning. A permeability study of vacuum chamber was implemented during the booster ring hardware testing. The magnetic field of magnets is distorted by the permeability of vacuum chamber. Study of multipole errors due to magnetized vacuum chamber inside the magnet will be discussed.
	Slides TUAD1 [2.698 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUAD1
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWA006	SIRIUS ACCELERATORS STATUS REPORT	storage-ring, booster, dipole, quadrupole	1403
	A.R.D. Rodrigues, F.C. Arroyo, O.R. Bagnato, J.F. Citadini, R.H.A. Farias, J.G.R.S. Franco, L. Liu, S.R. Marques, R.T. Neuenschwander, C. Rodrigues, R.M. Seraphim, O.H.V. Silva LNLS, Campinas, Brazil
	Sirius is a 3 GeV synchrotron light source that is being built by the Brazilian Synchrotron Light Laboratory (LNLS). The electron storage ring is based on a modified 5BA cell to achieve a bare lattice emittance of 0.27 nm.rad in a 518 m circumference ring that contains 20 straight sections of alternating 6 and 7 meters in length. The 5BA cell accommodates a thin permanent magnet high field (2 T) dipole in the center of the middle bend producing hard X-ray radiation (εc=12 keV) with a modest contribution to the total energy loss. In this paper we discuss the main achievements and issues for Sirius accelerators. Developments in beamlines are not discussed here.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA006
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWA012	SOLEIL Status Report	undulator, operation, photon, storage-ring	1419
	A. Nadji, Y.-M. Abiven, F. Bouvet, P. Brunelle, A. Buteau, N. Béchu, L. Cassinari, M.-E. Couprie, X. Delétoille, C. Herbeaux, N. Hubert, N. Jobert, M. Labat, J.-F. Lamarre, P. Lebasque, A. Lestrade, A. Loulergue, P. Marchand, O. Marcouillé, J.L. Marlats, L.S. Nadolski, R. Nagaoka, P. Prigent, K.T. Tavakoli, M.-A. Tordeux, M. Valléau SOLEIL, Gif-sur-Yvette, France
	The 2.75 GeV synchrotron light source SOLEIL (France) delivers photons to 27 beamlines and 2 new ones are under construction. The commissioning of the Femtoslicing operation mode involving two beamlines is in progress. The uniform filling pattern is now available to users with a 500 mA stored beam current. The operation of the two canted and long beamlines ANATOMIX and Nanoscopium both using in-vacuum insertion devices (IDs) as a photon source has been raising challenges still under investigation. Upgrades of crucial subsystem equipment like magnet power supplies, storage ring RF input power couplers, and solid state amplifiers are continuing. New user requests for beam stability are under upgrade consideration. Other projects for the storage ring are ongoing such as the design and construction of new insertion devices, new multipole injection kicker, localised small and round photon beam production, as well as R&D on 500 MHz solid-state amplifiers. In parallel first studies for a future upgrade of the machine have been progressing.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA012
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWA016	Modeling of beam losses at ESRF	scattering, simulation, electron, detector	1430
	R. Versteegen, P. Berkvens, N. Carmignani, J. Chavanne, L. Farvacque, S.M. Liuzzo, B. Nash, T.P. Perron, P. Raimondi, K.B. Scheidt, S.M. White ESRF, Grenoble, France
	As the ESRF enters the second phase of its upgrade towards ultra low emittance, the knowledge of the beam loss pattern around the storage ring is needed for radiation safety calculations and for the new machine design optimization. A model has been developed to simulate the Touschek scattering and the scattering of electrons on residual gas nuclei in view of producing a detailed loss map of the machine. Results of simulation for the ESRF are presented and compared with real beam measurements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA016
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWA025	Beam Heat Load Analysis with COLDDIAG: A Cold Vacuum Chamber for Diagnostics	electron, storage-ring, diagnostics, synchrotron	1459
	R. Voutta, S. Casalbuoni, S. Gerstl, A.W. Grau, T. Holubek, D. Saez de Jauregui KIT, Eggenstein-Leopoldshafen, Germany R. Bartolini, M.P. Cox, E.C. Longhi, G. Rehm, J.C. Schouten, R.P. Walker DLS, Oxfordshire, United Kingdom M. Migliorati, B. Spataro INFN/LNF, Frascati (Roma), Italy
	The knowledge of the heat intake from the electron beam is essential to design the cryogenic layout of superconducting insertion devices. With the aim of measuring the beam heat load to a cold bore and understanding the responsible mechanisms, a cold vacuum chamber for diagnostics (COLDDIAG) has been built. The instrumentation comprises temperature sensors, pressure gauges, mass spectrometers and retarding field analyzers, which allow to study the beam heat load and the influence of the cryosorbed gas layer. COLDDIAG was installed in the storage ring of the Diamond Light Source from September 2012 to August 2013. During this time measurements were performed for a wide range of machine conditions, employing the various measuring capabilities of the device. Here we report on the analysis of the measured beam heat load, pressure and gas content, as well as the low energy charged particle flux and spectrum as a function of the electron beam parameters.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA025
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWA044	Test electron source for increased brightness emission by near band gap photoemission	cathode, electron, emittance, simulation	1512
	S. Friederich, K. Aulenbacher IKP, Mainz, Germany
	Funding: Bundesministerium für Bildung und Forschung/Federal Ministry of Education and Research; Joint project HOPE A new photoemissive electron source is being built in order to make use of the reduction of ensemble temperature in near band gap photoemission. It will operate at up to 200 kV bias voltage with NEA GaAs photocathodes. High bunch charges will be investigated in pulsed mode with respect to the conservation of emittances at low energy excitations. High field gradients at the cathode surface will also allow further investigation of the field emission process of these photocathodes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA044
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWA048	Radiative Cooled Target for the ILC Polarized Positron Source	target, positron, photon, radiation	1526
	A. Ushakov University of Hamburg, Hamburg, Germany F. Dietrich, S. Riemann, T. Rublack DESY Zeuthen, Zeuthen, Germany P. Sievers CERN, Geneva, Switzerland
	Funding: Work supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Optimization", contract number 19XL7IC4 The target for the polarized positron source of the future International Linear Collider (ILC) is designed as wheel of 1 m diameter spinning with 2000 revolutions per minute to distribute the heat load. The target system is placed in vacuum since exit windows would not stand the load. In the current ILC design, the positron target is assumed to be water-cooled. Here, as an alternative, radiative cooling of the target has been studied. The energy deposition in the target is the input for ANSYS simulations. They include the temperature evolution as well as the corresponding thermo-mechanical stress in the target components. A principal design is suggested for further consideration.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA048
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWA062	GaAs Photocathode Activation with CsTe Thin Film	photon, electron, cathode, experiment	1567
	M. Kuriki, Y. Seimiya, K. Uchida HU/AdSM, Higashi-Hiroshima, Japan S. Kashiwagi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
	Funding: This work is partly supported by MEXT/JSPS KAKENHI (Grant-in-Aid for scientific research) 24654054. GaAs is an unique and advanced photocathode which can generate highly polarized and extremely low emittance electron beam. The photo-emission is possible up to 900nm wavelength. These advantages are due to NEA (Negative Electron Affinity) surface where the conduction band minimum is higher than the vacuum energy state. The NEA surface is artificially made with Cs-O/F evaporation on the cleaned GaAs surface, but the NEA surface is fragile, so that the emission is easily lost by poor vacuum environment and high emission density. NEA activation with any vital material is desirable. We found that the GaAs can be activated by CsTe thin film which is known as a vital photo-cathode material. The photo-electron emission spectrum extends up to 900 nm wavelength which corresponds to the band-gap energy of GaAs. The result strongly suggests that the surface becomes effectively NEA state by the CsTe thin film.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA062
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPJE010	Study of Cs-Te Photocathode for RF Electron Gun	electron, gun, radiation, scattering	1632
	S. Matsuzaki, M. Nishida, K. Sakaue, M. Washio Waseda University, Tokyo, Japan H. Iijima Tokyo University of Science, Tokyo, Japan
	At Waseda University, we have been studying high quality electron beam with an rf electron gun. In recent accelerator study and application researches, high quality electron beam are strongly required. Photocathode is a key component to generate higher quality electron beam. Cs-Te photocathode shows high quantum efficiency (Q.E.) (~10%) and has long life time (~several months). From 2013, we built a photocathode evaporation chamber and started photocathode study. In this study, our purpose is to clarify their property and to establish an ideal evaporation recipe. We succeeded in producing high quality Cs-Te photocathode, and electron beam generated by our Cs-Te photocathode shows high charge (4.6nC/bunch) and high Q.E. (1.74%) in our rf electron gun. Furthermore, we found a Q.E. recovery after Cs deposition process and it causes higher Q.E. than usual due to, we believe, Cs deposition quantity or Cs deposition speed. Thus we are now surveying the optimum Cs evaporation parameters. In this conference, we will report a detail of our photocathode development system, the latest progress of optimization study of Cs-Te photocathode and future plans. Work supported by Cooperative and Supporting Program for Researches and Educations in Universities and NEDO(New Energy and Industrial Technology Development Organization.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE010
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPJE036	A New Bench Concept for Measuring Magnetic Fields of Big Closed Structures	controls, operation, synchrotron, alignment	1690
	J. Campmany, F. Becheri, C. Colldelram, J. Marcos, V. Massana, J. Nicolás, L. Ribó ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	The measurement of big closed magnetic structures is becoming a challenge of great interest. The main reason is the tendency towards building accelerators with high magnetic fields produced by small gap magnets, as well as the development of cryogenic or superconducting narrow-gap insertion devices. Usual approach, based on side-measurements made with a Hall probe mounted on the tip of a motorized arm based on a long granite bench is no more applicable to such closed structures. So, new concepts and approaches have been developed, mainly based on complex devices that insert a Hall probe inside the magnetic structure maintaining the desired position by close-loop controls. The main problem of these devices is that they are not general-purpose oriented: they need a special vacuum chamber, require a specific geometry of the magnetic structure, or does not provide 3D field-map measurements. We present in this paper a new bench that has been built at ALBA synchrotron that is simple, multi-purpose and can be a general solution for measuring big closed structures.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE036
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPJE039	Recent Results on the Performance of Cs3Sb Photocathodes in the PHIN RF-Gun	cathode, gun, laser, operation	1699
	C. Heßler, E. Chevallay, S. Döbert, V. Fedosseev, I. Martini, M. Martyanov CERN, Geneva, Switzerland
	For the CLIC drive beam a photoinjector option is under study at CERN as an alternative to the thermionic electron gun in the CLIC baseline design. The CLIC drive beam requires a high bunch charge of 8.4 nC and 0.14 ms long trains with 2 ns bunch spacing, which is challenging for a photoinjector. In particular the required long and high intensity laser pulses cause a degradation of the beam quality during the frequency conversion process, which generates the ultra-violet laser beam needed for standard Cs2Te photocathodes. To overcome this issue Cs3Sb cathodes sensitive to green light have been studied at the high-charge PHIN photoinjector since a few years. In this paper recent measurements of fundamental properties of Cs3Sb photocathodes such as quantum efficiency, cathode lifetime and dark current from summer 2014 will be presented, and compared with previous measurements and with the performance of Cs2Te photocathodes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE039
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPJE050	Design of a Resonant Transition Radiation Source in the soft X-ray Range	photon, radiation, electron, resonance	1735
	P. Wang, K.C. Leou NTHU, Hsinchu, Taiwan N.Y. Huang, W.K. Lau, A.P. Lee NSRRC, Hsinchu, Taiwan
	Resonant transition radiation (RTR) can be generated from multi-layer structures when they are driven by relativistic electron beams. In consideration of using the NSRRC 90 MeV photoinjector as driver, we examined the feasibility of generating narrow-band soft x-rays from various multi-layer structures. Based on analytical theory, the expected angular-spectral distribution and photon yield of these radiators are calculated and compared.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE050
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPJE055	The Evolution of the Transverse Energy Distribution of Electrons from a GaAs Photocathode as a Function of its Degradation State	electron, detector, cathode, brightness	1748
	L.B. Jones, B.L. Militsyn, T.C.Q. Noakes STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom H.E. Scheibler, A.S. Terekhov ISP, Novosibirsk, Russia
	The brightness of a photoelectron injector is fundamentally limited by the mean longitudinal and transverse energy distributions of the photoelectrons emitted from its photocathode, and is increased significantly if the mean values of these quantities are reduced. To address this, ASTeC constructed a Transverse Energy Spread Spectrometer (TESS)* – an experimental facility designed to measure these transverse and longitudinal energy distributions which can be used for III-V semiconductor, alkali antimonide/telluride and metal photocathode research. We present measurements showing evolution of the transverse energy distribution of electrons from GaAs photocathodes as a function of their degradation state. Photocathodes were activated to negative electron affinity in our photocathode preparation facility (PPF)** with quantum efficiency around 10.5%. They were then transferred to TESS under XHV conditions, and progressively degraded through controlled exposure to oxygen. Data has been collected under photocathode illumination at 635 nm, and demonstrates a constant relationship between energy distribution and the level of electron affinity. * Proc. FEL ’13, TUPPS033, 290-293 ** Proc. IPAC '10, TUPE095, 2347-2349, Proc. IPAC ’11, THPC129, 3185-3187
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE055
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPJE064	Calibration of Fast Fiber-Optic Beam Loss Monitors for the Advanced Photon Source Storage Ring Superconducting Undulators	undulator, photon, simulation, electron	1780
	J.C. Dooling, K.C. Harkay, Y. Ivanyushenkov, V. Sajaev, A. Xiao ANL, Argonne, Ilinois, USA A. Vella University of Illinois at Urbana-Champaign, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357. We report on the calibration and use of fast fiber-optic (FO) beam loss monitors (BLMs) in the Advanced Photon Source storage ring (SR). A superconducting undulator prototype (SCU0) has been operating in SR Sector 6 since the beginning of CY2013, and another undulator SCU1 (a 1.1-m length undulator that is three times the length of SCU0) is scheduled for installation in Sector 1 in 2015. The SCU0 main coil often quenches during beam dumps. MARS simulations have shown that relatively small beam loss (<1 nC) can lead to temperature excursions sufficient to cause quenching when the SCU0 windings are near critical current. To characterize local beam losses, high-purity fused-silica FO cables were installed in Sector 6 next to the SCU0 cryostat and in Sector 1 where SCU1 will be installed. These BLMs aid in the search for operating modes that protect the SCU structures from beam-loss-induced quenching. In this paper, we describe the BLM calibration process that included deliberate beam dumps at locations of BLMs. We also compare beam dump events where SCU0 did and did not quench.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE064
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPJE078	Modeling of Impedance Effects for the APS-MBA Upgrade	impedance, wakefield, photon, simulation	1825
	R.R. Lindberg ANL, Argonne, Illinois, USA A. Blednykh BNL, Upton, Long Island, New York, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Understanding the sources of impedance is critical to accelerator design, and only becomes more important as vacuum chambers become smaller and closer to the electron beam. The multibend achromat upgrade at the Advanced Photon Source (APS) requires small, 22-mm diameter vacuum chambers and even smaller (6 mm) gaps for the insertion devices, so that both rf heating and wakefield-driven transverse instabilities become important concerns. We discuss modeling the primary sources of geometric impedance using the electromagnetic finite difference codes GdfidL and ECHO, and how these codes are influencing vacuum and accelerator component design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE078
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPJE079	High Charge Development of the APS Injector for an MBA Upgrade	booster, impedance, ion, injection	1828
	C. Yao, M. Borland, J.R. Calvey, K.C. Harkay, D. Horan, R.R. Lindberg, N. Sereno, H. Shang, X. Sun, J. Wang ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. The APS MBA (multi-bend achromat) upgrade storage ring will employ a “swap out” injection scheme and requires a single-bunch beam with up to 20 nC from the injector. The APS injector, which consists of a 450-MeV linac, a particle accumulator ring (PAR), and a 7-GeV synchrotron (Booster), was originally designed to provide up to 6 nC of beam charge. High charge injector study is part of the APS upgrade R&D that explores the capabilities and limitations of the injector through machine studies and simulations, and identifies necessary upgrades in order to meet the requirements of the MBA upgrade. In the past year we performed PAR and booster high charge studies, implemented new ramp correction of the booster rap supplies, explored non-linear chromatic correction of the booster, etc. This report presents the results and findings.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE079
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMA010	Development of a Field-Emission Type S-band RF-Gun System for High Brightness Electron Source Applications	cathode, gun, electron, emittance	1856
	Y.-M. Shin Northern Illinois University, DeKalb, Illinois, USA N. Barov Far-Tech, Inc., San Diego, California, USA A.T. Green Northern Illinois Univerity, Dekalb, Illinois, USA
	Electron beams emitted from a cold cathode are thermally stable and mono-energetic with a small phase-space volume. We have been developing a field-emission type RF-gun system for high brightness electron source applications, including electron scattering/diffraction and tunable coherent X-ray/THz generation. The system consists of a single-gap gun-cavity and an S-band klystron/modulator capable of powering the gun with up to 5.5 MW peak (PRR = 1 Hz, duration = 2.5 μs). The designed gun built with the symmetrised side-couplers has surface field on the cathode ranging 50 – 100 MV/m with 1.3 – 1.7 MW klystron-power and 1.2 field ratio (HFSS). ASTRA simulations also indicate that the gun produces the beam with transverse emittances of less than 1 mm-mrad with 10 – 20 pC bunch charge at 500 keV beam energy. Under the gun operating condition, particle tracking/PIC simulations (CST) show that a single-tip CNT field-emitter* produces short pulsed bunches (~ 1/10 RF-cycle) with small emittance ( 0.01 mm-mrad) and high peak current density ( 10,000 kA/cm²). After the gun is fully installed and commissioned, a CNT-tip cathode will be tested with RF-field emission. * N. De Jonge, J.-M. Bonard, Phil. Trans. R. Soc. Lond. A 362, 2239 (2004) ** G. S. Bocharov, and A. V. Eletskii, Nanomaterials 3, 393 (2013)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPMA010
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMA038	Observation of Significant Quantum Efficiency Enhancement from a Polarized Photocathode with Distributed Brag Reflector	laser, polarization, electron, cathode	1923
	S. Zhang, M. Poelker, M.L. Stutzman JLab, Newport News, Virginia, USA Y. Chen, A. Moy SVT Associates, Eden Prairie, Minnesota, USA
	Funding: This project was supported by the U.S. DOE Basic Energy Sciences under contract No. DE-AC05-060R23177. Polarized photocathodes with higher Quantum efficiency (QE) would help to reduce the technological challenge associated with producing polarized beams at milliampere levels, because less laser light would be required, which simplifies photocathode cooling requirements. And for a given amount of available laser power, higher QE would extend the photogun operating lifetime. The distributed Bragg reflector (DBR) concept was proposed to enhance the QE of strained-superlattice photocathodes by increasing the absorption of the incident photons using a Fabry-Perot cavity formed between the front surface of the photocathode and the substrate that includes a DBR, without compromising electron polarization. Here we present recent results showing QE enhancement of a GaAs/GaAsP strained-superlattice photocathode made with a DBR structure. Typically, a GaAs/GaAsP strained-superlattice photocathode without DBR provides a QE of 1%, at a laser wavelength corresponding to peak polarization. In comparison, the GaAs/GaAsP strained-superlattice photocathodes with DBR exhibited an enhancement of over 2 when the incident laser wavelength was tuned to meet the resonant condition for the Fabry-Perot resonator.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPMA038
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTY045	Interactions between Macroparticles and High-Energy Proton Beams	proton, electron, simulation, beam-losses	2112
	S. Rowan, A. Apollonio, B. Auchmann, A. Lechner, O. Picha, W. Riegler, H. Schindler, R. Schmidt, F. Zimmermann CERN, Geneva, Switzerland
	A known threat to the availability of the LHC is the interaction of macroparticles (dust particles) with the LHC proton beam. At the foreseen beam energy of 6.5 TeV during Run 2, quench margins in the superconducting magnets will be 2-3 times lower, and beam losses due such interactions may result in magnet quenches. The study introduce an improved numerical model of such interactions, as well as Monte-Carlo simulations that give the probability that such events will result in a beam-dump during Run 2.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY045
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTY049	Protection of Superconducting Magnets in Case of Accidental Beam Losses during HL-LHC Injection	injection, simulation, kicker, shielding	2128
	A. Lechner, M.J. Barnes, C. Bracco, B. Goddard, F.L. Maciariello, A. Perillo Marcone, N.V. Shetty, G.E. Steele, J.A. Uythoven, F.M. Velotti CERN, Geneva, Switzerland F.M. Velotti EPFL, Lausanne, Switzerland
	Funding: Research supported by the High Luminosity LHC project. The LHC injection regions accommodate a system of beam-intercepting devices which protect superconducting magnets and other accelerator components in case of mis-steered injected beam or accidentally kicked stored beam, e.g. due to injection kicker or timing malfunctions. The brightness and intensity increase required by the High Luminosity (HL) upgrade of the LHC necessitates a redesign of some devices to improve their robustness and to reduce the leakage of secondary particle showers to downstream magnets. In this paper, we review possible failure scenarios and we quantify the energy deposition in superconducting coils by means of FLUKA shower calculations. Conceptual design studies for the new protection system are presented, with the main focus on the primary injection protection absorber (TDI) and the adjacent mask (TCDD).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY049
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTY052	New Method for Validation of Aperture Margins in the LHC Triplet	optics, kicker, dumping, collimation	2140
	V. Chetvertkova, R. Schmidt, F.M. Velotti, D. Wollmann CERN, Geneva, Switzerland F.M. Velotti EPFL, Lausanne, Switzerland
	Funding: Work supported by COFUND grant PCOFUND-GA-2010-267194 Safety of LHC equipment including superconducting magnets depends not only on the proper functioning of the systems for machine protection, but also on the accurate adjustment of the protective devices such as collimators. In case of a failure of the extraction kicker magnets, which are part of the beam dumping system, it is important to ensure protection of the superconducting triplet magnets from missteered beam. The magnets are located to the right of Interaction Point 5 (IP5) and are protected by one set of collimators in the beam dumping insertion in IR6 and another set close to the triplet magnets. In this paper, a new method for verification of the correct collimator position with respect to the aperture is presented. It comprises the application of an extended orbit bump with identical trajectory as the beam trajectory after a deflection by the beam dump kickers. By further increasing the bump amplitude and successively moving in/out the collimators in the region of interest, the accurate positioning of the collimators can be validated. The effectiveness of the method for LHC IP5 and IP1 and both beams is discussed
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY052
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTY072	A New ILC Positron Source Target System Using Sliding Contact Cooling	target, positron, radiation, undulator	2196
	W. Gai, D.S. Doran, R.A. Erck, G.R. Fenske, V.J. Guarino, W. Liu ANL, Argonne, Illinois, USA
	The R&D of the baseline positron source target for ILC is still ongoing after TDR due to the uncertainty of rotating vacuum seal and water cooling system of the fast spinning target wheel. Different institutes around the globe have proposed different approaches to tackle this issue. A spinning target wheel system with sliding contact cooling has been proposed by ANL. The proposed system eliminated the needs of rotating vacuum seal by using magnet bearings and vacuum compatible motor driven solid spinning wheel target. The energy deposited from positron production process is taken away via sliding cooling pads sliding against the spinning wheel. Details about this new target system are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY072
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTY079	Initial Modeling of Electron Cloud Buildup in the Final-focus Quadrupole Magnets of the SuperKEKB Positron Ring	electron, photon, quadrupole, positron	2218
	J.A. Crittenden Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: US National Science Foundation contracts PHY-0734867, PHY-1002467, and PHY-1068662, US Department of Energy contract DE-FC02-08ER41538 and the Japan/US Cooperation Program We present modeling results for electron cloud buildup in the final-focus quadrupole magnet nearest the interaction point in the SuperKEKB positron storage ring. The calculations employ as input recently obtained estimates of synchrotron radiation absorption rates on the vacuum chamber wall including the effect of photon scattering. While the effect both adds to and subtracts from photoelectron production at the points in the ring where unscattered photons strike the wall, it also produces cloud in the other regions. Results for beam-pipe-averaged and beam-averaged cloud densities are presented, as are estimates for the contribution to the fractional vertical coherent tune shift. The effect of the strong magnetic fields is studied and the dependence on the vacuum chamber surface secondary yield characteristics is considered. Cloud buildup is modeled with a 2D particle-in-cell macroparticle tracking code validated using recent measurements of electron trapping in a quadrupole magnet at the Cornell Electron Storage Ring Test Accelerator.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY079
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTY080	Synchrotron Radiation Analysis of the SuperKEKB Positron Storage Ring	photon, positron, scattering, electron	2222
	J.A. Crittenden, D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA T. Ishibashi, Y. Suetsugu KEK, Ibaraki, Japan
	Funding: US National Science Foundation contracts PHY-0734867, PHY-1002467, and PHY-1068662, US Department of Energy contract DE-FC02-08ER41538 and the Japan/US Cooperation Program. We report on modeling results for synchrotron radiation absorption in the SuperKEKB positron storage ring vacuum chamber including the effects of photon scattering on the interior walls. A detailed model of the geometry of the inner vacuum chamber profile has been developed and used as input to a photon tracking code. Particular emphasis is placed on the photon absorption rates in the electron-positron interaction region.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY080
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEBD2	Survey of Commissioning of Recent Storage Ring Light Sources	survey, factory, synchrotron, lattice	2482
	M. Borland ANL, Argonne, Ilinois, USA R. Bartolini, I.P.S. Martin DLS, Oxfordshire, United Kingdom L.O. Dallin CLS, Saskatoon, Saskatchewan, Canada P. Kuske, R. Müller HZB, Berlin, Germany L.S. Nadolski SOLEIL, Gif-sur-Yvette, France F. Pérez ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain J.A. Safranek SLAC, Menlo Park, California, USA S. Shin PAL, Pohang, Kyungbuk, Republic of Korea Z.T. Zhentang SINAP, Shanghai, People's Republic of China
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The Advanced Photon Source and other existing storage ring light sources are contemplating replacing an existing, operating storage ring with a multi-bend achromat lattice. One issue is that existing light sources have large user communities who are greatly inconvenienced by extended shutdowns. Hence, there will be a premium placed on rapid commissioning of the new lattice. To better understand the possibilities, we undertook a survey of recent commissioning experience at third-generation light sources. We present a summary of that survey here.
	Slides WEBD2 [0.173 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEBD2
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEBD3	Recent Developments on Superconducting Undulators at ANKA	undulator, operation, storage-ring, permanent-magnet	2485
	S. Casalbuoni, A. Cecilia, S. Gerstl, N. Glamann, A.W. Grau, T. Holubek, C.A.J. Meuter, D. Saez de Jauregui, R. Voutta KIT, Eggenstein-Leopoldshafen, Germany C. Boffo, T.A. Gerhard, M. Turenne, W. Walter Babcock Noell GmbH, Wuerzburg, Germany
	At the synchrotron ANKA (ANgstrom source KArlsruhe) we pursue a research and development program on superconducting undulators (SCUs). This technology is of interest to improve the spectral characteristics of the emitted photons in third and fourth generation light sources. We present here the results obtained within the ongoing collaboration with the industrial partner Babcock Noell GmbH (BNG) on NbTi conduction cooled planar devices. Investigations on the application of alternative superconductors as well as a summary of the achievements reached to precisely characterize the magnetic field properties of SCUs and to measure the beam heat load to a cold bore are also described.
	Slides WEBD3 [2.581 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEBD3
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA016	CsKSb Photocathode R&D with High Quantum Efficiency and Long Lifetime	laser, cathode, electron, linac	2526
	Y. Seimiya, R. Kaku, M. Kuriki, A. Yokota HU/AdSM, Higashi-Hiroshima, Japan T. Konomi UVSOR, Okazaki, Japan T. Miyajima, M. Yamamoto KEK, Ibaraki, Japan
	Advanced electron linear accelerator such as Energy Recovery Linac and Free Electron Laser needs high brightness electron source. Photocathode is suitable for the high brightness requirement because some of them has low emittance and high quantum efficiency. In the photocathode, CsKSb multi-alkali photocathode has excellent features: high quantum efficiency, long lifetime, and driven by visible light, for example green laser. Therefore, the multi-alkali photocathode is considered to be one of the best candidates for the high brightness electron source of the advanced electron accelerator. We report developments of our evaporation system and results of quantum efficiency and lifetime measurement in Hiroshima University. Multi-alkali surface analyzation has being measured by ultra-violet photoemission spectroscopy to study conditions between the multi-alkali performances and the surface condition in Institute Molecular Science. We also report the status of the progress abort the study.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA016
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA037	Beam-Driven Terahertz Source Based on Open Ended Waveguide with a Dielectric Layer: Rigorous Approach	radiation, interface	2578
	S.N. Galyamin, A.A. Grigoreva, A.V. Tyukhtin, V.V. Vorobev Saint-Petersburg State University, Saint-Petersburg, Russia
	Funding: Grant of the President of Russian Federation (No. 6765.2015.2) and Russian Foundation for Basic Research (No. 15-32-20985, 15-02-03913). Terahertz frequency radiation (0.1-10 THz) is a promising tool for a number of scientific and practical applications. One promising scheme to obtain powerful and efficient THz emission is usage of beam-driven dielectric loaded structures [1]. Recently we have considered the problem where the microbunched ultrarelativistic charge exits the open end of a cylindrical waveguide with a dielectric layer and produces THz waves in a form of Cherenkov radiation [2]. To investigate the applicability of utilized approximations, we analyze here the case of orthogonal end of a waveguide with continuous filling. However, presented rigorous approach can be generalized for waveguide with vacuum channel. We use the combination of Wiener-Hopf technique and tailoring technique. The infinite linear system for magnitudes of reflected waveguide modes is obtained and solved numerically. We present typical field distributions over the aperture and typical radiation patterns in the Fraunhofer zone. * S. Antipov et al., Appl. Phys. Lett. 100, 132910 (2012). ** S.N. Galyamin et al., Opt. Express. 22(8), 8902 (2014).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA037
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA038	Mode Transformation in Waveguide with Transversal Boundary Between Vacuum and Partially Dielectric Area	wakefield, radiation, acceleration, electron	2581
	A.A. Grigoreva, T.Yu. Alekhina, S.N. Galyamin, A.V. Tyukhtin Saint-Petersburg State University, Saint-Petersburg, Russia
	We consider the mode transformation in a circular waveguide with a transversal boundary between a vacuum part and a part with a cylindrical dielectric layer and a vacuum channel. It is assumed that an incident mode can be both propagating and evanescent. Analysis is carried out with the using the mode decomposition technique. Numerical algorithm for calculating the mode transformation at an arbitrary channel radius is also developed. Typical dependences for the reflection and transmission coefficients on the channel radius are presented and discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA038
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA051	Investigations into Dielectric Laser-Driven Accelerators using the CST and VSIM Simulation Codes	acceleration, electron, laser, simulation	2618
	Y. Wei, C.P. Welsch, G.X. Xia Cockcroft Institute, Warrington, Cheshire, United Kingdom K. Hanahoe, K. Hanahoe, O. Mete, G.X. Xia UMAN, Manchester, United Kingdom J. Smith Tech-X, Boulder, Colorado, USA Y. Wei, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	Funding: European Union’s 7th Framework Programme for research, development and demonstration under grant agreement no 289191 and the STFC Cockcroft core grant No.ST/G008248/1. Dielectric laser-driven accelerators (DLAs) based on gratings structures confine the laser-induced accelerating field in a narrow vacuum channel where the electrons travel and are being accelerated. Recent proof-of-principle experiments have successfully demonstrated acceleration of electrons with accelerating gradients of up to 250 MV/m in such novel structures. This contribution presents detailed numerical studies into the acceleration of relativistic and non-relativistic electrons in double gratings silica structures. The optimization of these structures with regards to maximum acceleration efficiency for different spatial harmonics is discussed. Simulations were carried out using the commercial CST and VSIM simulation codes and results from both codes are shown in comparison.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA051
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA052	RF Conditioning of the Photo-Cathode RF Gun at the Advanced Photon Source - NWA RF Measurements	gun, detector, cathode, linac	2621
	T.L. Smith, N.P. DiMonte, A. Nassiri, Y.-E. Sun, A. Zholents ANL, Argonne, Illinois, USA
	Funding: Work supported by U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357 A new S-band photo-cathode (PC) gun was recently installed and RF conditioned at the Advanced Photon Source (APS) Injector Test-stand (ITS) at Argonne National Lab (ANL). The APS PC gun is a LCLS type gun fabricated at SLAC [1]. The PC gun was delivered to the APS in October 2013 and installed in the APS ITS in December 2013. At ANL, we developed a new method of fast detection and mitigation of the gun’s internal arcs during the RF conditioning process to protect the gun from arc damage and to RF condition more efficiently. Here, we report the results of RF measurements for the PC gun and an Auto-Restart method for high power RF conditioning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA052
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA068	Simulation of Laser Pulse Driven Terahertz Generation in Inhomogeneous Plasmas	plasma, radiation, laser, simulation	2661
	C.M. Miao, T.M. Antonsen UMD, College Park, Maryland, USA J. Palastro Icarus Research, Inc., Bethesda, Maryland, USA
	Intense, short laser pulses propagating through inhomogeneous plasma can ponderomotively drive THz radiation. Here we consider a transition radiation mechanism (TRM) for THz generation as a laser pulse crosses a plasma boundary. Full format PIC simulations and theoretical analysis are conducted demonstrating that TRM results in low frequency, broad band, coherent THz radiation. The effect of a density ramp is also considered and shown to enhance the radiated energy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA068
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPJE021	Fabrication and Demonstration of a Silicon Buried Grating Accelerator	electron, laser, acceleration, simulation	2717
	A.C. Ceballos, R.L. Byer, K.J. Leedle, E.A. Peralta, O. Solgaard, K. Soong Stanford University, Stanford, California, USA R.J. England, I.V. Makasyuk, K.P. Wootton, Z. Wu SLAC, Menlo Park, California, USA A. Hanuka Technion, Haifa, Israel A.D. Tafel Friedrich-Alexander Universität Erlangen-Nuernberg, University Erlangen-Nuernberg LFTE, Erlangen, Germany
	Funding: Work supported by the U.S. Department of Energy under Grants DE-AC02-76SF00515, DE-FG06-97ER41276. Using optical electromagnetic fields in dielectric microstructures, we can realize higher-energy accelerator systems in a more compact, low-cost form than the current state-of-the-art. Dielectric, laser-driven accelerators (DLA) have recently been demonstrated using fused silica structures to achieve about an order-of-magnitude increase in accelerating gradient over conventional RF structures.* We leverage higher damage thresholds of silicon over metals and extensive micromachining capability to fabricate structures capable of electron acceleration. Our monolithic structure, the buried grating, consists of a grating formed on either side of a long channel via a deep reactive ion etch (DRIE).** The grating imposes a phase profile on an incoming laser pulse such that an electron experiences a net change in energy over the course of each optical cycle. This results in acceleration (or deceleration) as electrons travel down the channel. We have designed and fabricated such structures and begun testing at the SLAC National Accelerator Laboratory. We report on the progress toward demonstration of acceleration in these structures driven at 2um wavelength. * E.A. Peralta et al., Nature 503 (2013) ** C.M. Chang and O. Solgaard, Appl. Phys. Lett. 104 (2014)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPJE023	Cathode Performance during Two Beam Operation of the High Current High Polarization Electron Gun for eRHIC	cathode, gun, electron, operation	2720
	O.H. Rahman Stony Brook University, Stony Brook, USA M.A. Ackeret, J.R. Pietz Transfer Engineering and Manufacturing, Inc, Fremont, California, USA I. Ben-Zvi, C. Degen, D.M. Gassner, R.F. Lambiase, A.I. Pikin, T. Rao, B. Sheehy, J. Skaritka, E. Wang BNL, Upton, Long Island, New York, USA E. Dobrin, R.C. Miller, K.A. Thompson, C. Yeckel Stangenes Industries, Palo Alto, California, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Two electron beams from two activated bulk GaAs photocathodes were successfully combined during the recent beam test of the High Current High Polarization Electron gun for eRHIC. The beam test took place at Stangenes Industries in Palo Alto, CA, where the cathodes were placed in radially opposite locations inside the high voltage shroud. No significant cross talking between the cathodes were found for the pertinent vacuum and low average current operation, which is very promising towards combining multiple beams for higher average current. This paper describes the cathode preparation, transport and cathode performance in the gun for the combining test, including the QE and lifetimes of the photocathodes at various steps of the experiment.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE023
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA003	Vacuum System Design for the Sirius Storage Ring	radiation, storage-ring, dipole, synchrotron	2744
	R.M. Seraphim, O.R. Bagnato, R.O. Ferraz, H.G. Filho, G.R. Gomes, M. Nardin, R.F. Oliveira, B.M. Ramos, A.R.D. Rodrigues, M.B. Silva, T.M. da Rocha LNLS, Campinas, Brazil
	Sirius is a 3 GeV 4th-generation light source under construction by the Brazilian Synchrotron Light Laboratory (LNLS). Sirius will have a low emittance storage ring, 0.28 nm-rad, based on 20 cells of a highly compact lattice – 5-bend achromat (5BA). This lattice concept leaves very little space for components and therefore requires narrow vacuum chambers with tight mechanical tolerances. Most of the storage ring vacuum chambers will be made of OFS copper and have a circular cross section with inner diameter of 24 mm and a wall thickness of 1 mm. The unused synchrotron radiation will be distributed along the water cooled walls of the chambers. Due to the small conductance of the chambers, the vacuum pumping will be based on distributed concept and then non-evaporable getter (NEG) coating will be extensively used, with more than 95% of the chambers being coated. In this paper, we present an overview of the storage ring vacuum system and the main vacuum chambers fabrication developments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA003
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA007	Experimental Study of Multipactor Suppression in Dielectric Materials	multipactoring, electron, Windows, target	2753
	M. El Khaldi, W. Kaabi LAL, Orsay, France
	A novel coaxial resonator to investigate two-surface multipactor discharges on metal and dielectric surfaces in the gap region under vacuum conditions (~10^-8 mbar) has been designed and tested. The resonator is ~ 100 mm in length with an outer diameter of ~ 60 mm (internal dimensions). A pulsed RF source delivers up to 30 W average power over a wide frequency range 650-900 MHz to the RF resonator. The incident and reflected RF signals are monitored by calibrated RF diodes. An electron probe provides temporal measurements of the multipacting electron current with respect to the RF pulses. In this paper we compare and contrast the results from the RF power tests of the alumina (97.6% Al2O3) and quartz samples without a coating, “the non-coated samples” and the Alumina and quartz samples with a thick TiN coating in order to evaluate a home made sputtered titanium nitride (TiN) thin layers as a Multipactor suppressor. The effectiveness of this method is presented and discussed in the paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA007
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA008	RF Design of a High Gradient S-Band Travelling Wave Accelerating Structure for Thomx Linac	accelerating-gradient, impedance, linac, simulation	2757
	M. El Khaldi, L. Garolfi LAL, Orsay, France
	There is growing demand from the industrial and research communities for high gradient, compact RF accelerating structures. The Thomx high gradient structure (HGS) is travelling wave (TW), quasi constant gradient section and will operate at 2998.55 MHz (30°C in vacuum) in the 2π/3 mode. The optimization of the cell shape (Electromagnetic design) has been carried out with the codes HFSS and CST MWS, in order to improve the main RF characteristics of the cavity such as shunt impedance, accelerating gradient, group velocity, modified Poynting vector, surface fields, etc. Prototypes with a reduced number of cells have been designed. For an input power of about 20 MW, EM simulation results show that an average accelerating gradient of 28 MV/m is achieved which corresponds to a peak accelerating gradient of 35 MV/m, a peak surface gradient of 44 MV/m and peak modified Poynting vector S_cmax of 0.24 MW/mm².
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA008
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA023	Advanced Multipoles and Appropriated Measurement Tools for Field Characterization of SIS100 Magnets	multipole, dipole, superconducting-magnet, ion	2805
	P. Schnizer, E.S. Fischer, A. Gottsmann, F. Kaether, A. Mierau, H.G. Weiss GSI, Darmstadt, Germany B. Schnizer TUG/ITP, Graz, Austria
	The heavy ion synchrotron SIS100 utilises fast ramped superconducting magnets. Describing and measuring these magnets requires advanced multipoles next to well adapted measurement techniques. We cover briefly the required theory adapted to the measurements, show which designs were available and which decisions had to be taken for measuring curved superconducting magnets. The series of SIS100 dipole magnets is going to be produced. These magnets will be measured at GSI. We present the foreseen field measurement procedure, outline the currently ongoing tests and give our calibration strategy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA023
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA034	Bakeout Concept for the HESR at FAIR	dipole, ion, heavy-ion, controls	2832
	H. Jagdfeld, N. Bongers, P. Chaumet, F.M. Esser, F. Jordan, F. Klehr, G. Langenberg, U. Pabst, L. Semke FZJ, Jülich, Germany
	Forschungszentrum Jülich has taken the leadership of a consortium being responsible for the design of the High-Energy Storage Ring (HESR) going to be part of the FAIR project at GSI. The HESR is designed for antiprotons but can be used for heavy ion experiments as well. Therefore the vacuum is expected to be 10^-11 mbar or better. To achieve this also in the curved sections where 44 bent dipole magnets with a length of around 4.5 m will be installed, NEG coated dipole chambers will be used to reach the needed pumping speed and capacity. For activation of the NEG-material a bakeout system must be installed. The bakeout concept including the layout of the control system and the systematization of the heater packages for all components of the vacuum system are presented. Also the special design of the heater jackets inside the dipole will be shown where the geometrical parameters are very critical and space is very limited. The results of the simulation of temperature distribution in the dipole iron are compared to temperature measurements carried out at a testbench with different layouts of the heater jackets. The final design of the dipole heater jackets will be illustrated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA034
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA037	Manufacturing and First Test Results of Euclid SRF Conical Half-wave Resonator	cavity, niobium, SRF, cryogenics	2841
	E.N. Zaplatin FZJ, Jülich, Germany C.H. Boulware, T.L. Grimm, A. Rogacki Niowave, Inc., Lansing, Michigan, USA A. Kanareykin Euclid TechLabs, LLC, Solon, Ohio, USA V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Funding: This Work is supported by the DOE SBIR Program, contract # DE-SC0006302. Euclid TechLabs has developed a superconducting conical half-wave resonator (162.5 MHz β=v/c=0.11) for the high-intensity proton accelerator complex proposed at Fermi National Accelerator Laboratory. The main objective of this project is to provide a resonator design with high mechanical stability based on an idea of the balancing cavity frequency shifts caused by external loads. A unique cavity side-tuning option has been successfully implemented. Niowave, Inc. proposed a complete cavity production procedure including preparation of technical drawings, processing steps and resonator high-gradient tests. During manufacturing a series of cavity and helium vessel modifications to simplify their manufacturing were proposed. Following standard buffered chemical polish surface treatment and high-pressure rinse, a vertical test was carried out at Niowave’s facilities. Here we present the status of the project and the first high-gradient results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA037
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA038	Compact In-vacuum Quadrupoles for a Beam Transport System at a Laser Wakefield Accelerator	quadrupole, operation, focusing, laser	2845
	A. Bernhard, V. Afonso Rodríguez, A.-S. Müller, J. Senger, W. Werner, C. Widmann KIT, Karlsruhe, Germany
	Funding: This work is partially funded by the German Federal Ministry for Education and Research under contract no. 05K10VK2 and 05K10SJ2. For the transport and matching of electrons generated by a Laser Wakefield Accelerator (LWFA) a beam transport system with strong focusing magnets and a compact design is required. For the realization of such a beam transport system at the LWFA in Jena, Germany, two small series of inexpensive, modular quadrupoles were designed and built. The quadrupoles are iron-dominated electromagnets in order to keep the transport system adaptable to different energies and target parameters. To achieve the required field strength it was necessary to choose a small magnetic aperture. Therefore the magnets were designed for in-vacuum use with water-cooled coils. In this contribution the design, the realization and first field measurements of these quadrupoles are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA038
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA047	MHI's Production Activities of Accelerator Components	network, status, coupling, LLRF	2873
	N. Shigeoka, S. Miura MHI, Hiroshima, Japan
	Mitsubishi Heavy Industries (MHI) is manufacturing various types of accelerator components. Recent production activities, mainly in a field of a normal conducting RF, will be reported in this presentation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA047
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA049	Development of the Ceramic Chamber Integrated Pulsed Magnet Fitting for a Narrow Gap	power-supply, dipole, storage-ring, kicker	2879
	C. Mitsuda, T. Honiden, N. Kumagai, S. Sasaki JASRI/SPring-8, Hyogo-ken, Japan T. Nakanishi SES, Hyogo-pref., Japan A. Sasagawa KYOCERA Corporation, Higashiomi-city, Shiga, Japan
	We are pushing forward the development of a pulsed magnet that has a combined structure of magnet coils with a ceramic vacuum chamber, aiming to realize a small gap. The structure we are developing is that single turn air-coils are implanted along the longitudinal axis in the cylindrical ceramic chamber wall with thickness of 5mm. The ceramic wall works for separating the vacuum from the atmosphere, as well as holding the coil structures mechanically and the electrical insulation of coils. By this structure, magnet pole edges can be set close to the inside diameter of the chamber. The small gap increases magnetic field strength, which is for shorter length, and, as a result, the small magnet size reduces the inductance, which is for shorter pulse. We achieved the continuous operation over 200 days, without any failure, of current-excitation with 20 kV, 7.7 kA pulse with 4-μsec width and repetition of 1 Hz, using the dipole type prototype with a bore radius of 30 mm and magnetic length of 0.3m in 2013, while maintaining the vacuum pressure less than 10^-6 Pa. In this conference, we will discuss about the availability and practical utility with the magnetic field output performance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA049
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA059	Degassing of Kicker Magnet by In-situ Bake-out Method	kicker, radiation, plasma, shielding	2911
	J. Kamiya, Y. Hikichi, M. Kinsho, N. Ogiwara JAEA/J-PARC, Tokai-mura, Japan

Paper

Title

Other Keywords

Page

MOBD1

Preliminary Design of the High-Luminosity LHC Beam Screen with Shielding

shielding, luminosity, cryogenics, impedance

60

C. Garion, V. Baglin, R. Kersevan
CERN, Geneva, Switzerland

A new beam screen is needed in the High-Luminosity LHC (HL-LHC) final focusing magnets. Such an essential vacuum component, while operating in the range 40-60 K, has to ensure the vacuum performance and to prevent the beam-induced heating from reaching the cold bore which is at 1.9 K. In addition, they have to shield the cold mass from physics debris coming from the nearby beam collision points. To such purpose, energy absorbers made of tungsten alloy are installed onto the beam screen in the vacuum system. In this contribution, the proposed mechanical design is shown; it covers different thermomechanical aspects such as the behaviour during a magnet quench and the heat transfer from the tungsten absorbers to the cooling tubes. Assembly and manufacturing tolerances are also considered to evaluate the impact on the aperture. Results obtained with a short prototype assembly test are discussed.

Slides MOBD1 [3.089 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOBD1

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWA006

Core-Halo Limit as an Indicator of High Intensity Beam Internal Dynamics

space-charge, emittance, linac, simulation

86

P.A.P. Nghiem, N. Chauvin, N. Pichoff, D. Uriot, M. Valette
CEA/DSM/IRFU, France

The dynamics of high-intensity beams is mainly governed by their internal space charge forces. These forces induce emittance growth and halo generation. They contribute to shape the beam density profile. As a consequence, a careful analysis of this profile can help revealing the internal dynamics of the beam. This paper recalls the precise core-halo limit determination proposed earlier *, then studies its behavior through a wide range of beam profiles and finally shows its relevance as an indicator of the limit separating the two specific space charge field regimes of the core and the halo.
* P. A. P. Nghiem et al., Appl. Phys. Lett. 104, 074109 (2014)

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA006

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWA066

Simulation on Buildup of Electron Cloud in Rapid Cycling Synchrotron of China Spallation Neutron Source

electron, proton, simulation, neutron

275

K.W. Li, L. Huang, Y.D. Liu, S. Wang
IHEP, Beijing, People's Republic of China

Funding: Work supported by National Natural Science Foundation of China (11275221)
Electron cloud interaction with high energy positive beam are believed responsible for various undesirable effects such as vacuum degradation, collective beam instability and even beam loss in high power proton circular accelerator. An important uncertainty in predicting electron cloud instability lies in the detail processes on the generation and accumulation of the electron cloud. The simulation on the build-up of electron cloud is necessary to further studies on beam instability caused by electron cloud. China Spallation Neutron Source (CSNS) is the largest scientific project in building, whose accelerator complex includes two main parts: an H⁻ linac and a rapid cycling synchrotron (RCS). The RCS accumulates the 80 MeV proton beam and accelerates it to 1.6 GeV with a repetition rate 25 Hz. During the beam injection with lower energy, the emerging electron cloud may cause a serious instability and beam loss on the vacuum pipe. A simulation code has been developed to simulate the build-up, distribution and density of electron cloud in CSNS/RCS.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA066

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE026

Revision of the Impedance Model for the Interpretation of the Single Bunch Measurements at ALBA

impedance, undulator, simulation, storage-ring

330

T.F.G. Günzel, U. Iriso
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

Recent measurements showed that the ALBA transverse impedance model was able to explain 65% of the measured single bunch vertical detuning. * This report shows the revision of the impedance model developed to match latest single bunch measurements performed to evaluate the total effective machine impedance and impedance of specific elements, like in-vacuum undulators or a recently installed pinger magnet. The model improvement includes a better bunch length parameterisation, re-calculation of several vacuum chamber elements with Gdfidl, and inclusion of elements neglected so far in the impedance budget. We also show and discuss the computation of the resistive wall impedance using ImpedanceWake2D.
* T.Günzel, U.Iriso, F.Perez, E.Koukovini-Platia, G.Rumolo, "Analysis of the single bunch measurements at the ALBA Storage Ring", TUPRI052, proc. of IPAC14 (2014).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE026

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE027

Beam-based Impedance Characterization of the ALBA Pinger Magnet

impedance, simulation, injection, synchrotron

334

U. Iriso, T.F.G. Günzel
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
H. Bartosik, E. Koukovini-Platia, G. Rumolo
CERN, Geneva, Switzerland

The ALBA pinger magnet consists on two short kickers (for horizontal and vertical planes) installed in a single Titanium coated ceramic vacuum chamber. Single bunch measurements in the vertical plane were performed in the ALBA Synchrotron Light Source before and after the pinger installation, and by comparing the Transverse Mode Coupling Instability (TMCI) thresholds for zero chromaticity, we infer the pinger impedance and compare it with the model predictions. We also perform measurements for negative chromaticities and results are reported in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE027

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE035

An Extended SPS Longitudinal Impedance Model

impedance, kicker, simulation, resonance

360

J.V. Campelo, T. Argyropoulos, T. Bohl, F. Caspers, J. F. Esteban Müller, J.B. Ghini, A. Lasheen, D. Quartullo, B. Salvant, E.N. Shaposhnikova, C. Zannini
CERN, Geneva, Switzerland

Longitudinal multi-bunch instability in the CERN SPS with a very low intensity threshold is a serious limitation for the future doubling of bunch intensity required by Hi-Lumi LHC project. A complete and accurate impedance model is essential to understand the nature of this instability and to plan possible cures. This contribution describes in detail the current longitudinal impedance model of the SPS. Recently, the model was updated with new findings and includes now the impedance of accelerating cavities, kicker and septum magnets, beam position monitors, vacuum Flanges, shielded and unshielded pumping ports, electrostatic septa and resistive wall. Electromagnetic simulations and bench measurements were used to build the model. The contribution from each element is described and compared to the total machine impedance. Together with relevant beam measurements and simulations, the analysis of the different sources of impedance is used to identify the source of the longitudinal instability limiting the SPS performance so that the responsible elements can be acted upon.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE035

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE036

Longitudinal Impedance Characterization of the CERN SPS Vacuum Flanges

impedance, resonance, simulation, damping

363

J.V. Campelo
CERN, Geneva, Switzerland

This contribution describes the thorough studies carried out to characterize the longitudinal impedance of the CERN SPS vacuum flanges, which are believed to be the main source of LHC beam instability. Around 500 high-impedance flanges of 8 different types have been identified. Three factors play an important role in the characterization of these flanges: the type of vacuum chambers that the flange interconnects, whether or not both sides are electrically isolated (by means of an enamel coating) and, finally, the presence of damping resistors which damp high-Q resonances. Not only, full-wave electromagnetic field simulations, but also RF measurements have been used to evaluate the impedance of these elements. The R/Q of the relevant resonances was measured using the well-known bead-pull technique. In particular, a subset of around 150 flanges has been found to be the source of a high-impedance resonance at 1.4 GHz, also observed in beam measurements. Guidelines on how to reduce the impedance of these elements are also presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE036

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE037

Study and Comparison of Mode Damping Strategies for the UA9 Cherenkov Detector Tank

damping, cavity, detector, resonance

366

A. Danisi, F. Caspers, R. Losito, A. Masi, B. Salvant, C. Vollinger
CERN, Geneva, Switzerland
T. Demma, P. Lepercq
LAL, Orsay, France

In the framework of the UA9 experiment, the Cherenkov detector is useful to measure the amount of particles deflected by a bent crystal, proving the crystal collimation principle. The tank used to host this device is taken as a case study for an in-depth analysis of different damping strategies for electromagnetic modes which otherwise would give rise to important beam-coupling impedance contributions. Such strategies involve the use of ferrite, damping resistors and a mode-coupler, a solution which intercepts the modes inside the cavity but damps the related power outside the vacuum tank (potentially avoiding heating). Such solutions are discussed through experimental measurements and the relative quality factor is taken as a figure of merit.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE037

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE043

Design and Optimization of Electrostatic Deflectors for ELENA

focusing, antiproton, alignment, simulation

382

D. Barna
University of Tokyo, Tokyo, Japan
W. Bartmann, M.A. Fraser, R. Ostojić
CERN, Geneva, Switzerland

The ELENA ring will decelerate the antiprotons ejected from the Antiproton Decelerator (AD) at 5.3 MeV down to 100 keV kinetic energy. The slow antiprotons will be delivered to experiments using electrostatic beamlines, consisting of quadrupoles, correctors and deflectors. An extensive simulation study was carried out to find solutions to minimize the aberrations of the deflectors. These solutions will be presented together with the actual design of these devices.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE043

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE045

Fixed Points in Presence of Space Charge in Circular Particle Accelerators

space-charge, simulation, extraction, resonance

389

M. Giovannozzi, S.S. Gilardoni, A. Huschauer
CERN, Geneva, Switzerland
S. Machida, C.R. Prior, S.L. Sheehy
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

Recent measurements performed in the framework of the multi-turn extraction (MTE) studies showed a dependence of the position of beamlets obtained by crossing a stable transverse resonance on the total beam intensity. This novel observation has triggered a number of studies aiming at understanding the source of the observed effect. In this paper the results of numerical simulations performed in different conditions are discussed in detail.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE045

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE049

Benchmarking the CERN-SPS Transverse Impedance Model with Measured Headtail Growth Rates

impedance, simulation, kicker, optics

402

C. Zannini, H. Bartosik, G. Iadarola, G. Rumolo, B. Salvant
CERN, Geneva, Switzerland

The latest SPS transverse impedance model includes kicker magnets, wall impedance, transition pieces (e.g. flanges and vacuum chamber discontinuities), beam position monitors and RF cavities. The model has already been successfully benchmarked against coherent tune shift and transverse mode coupling instability measurements. In this paper we present measurements of the headtail growth rates for a wide range of negative chromaticities and for two different configurations of machine optics (nominal and low gamma transition). The measurement results are compared with HEADTAIL simulations using the wake fields obtained from the SPS transverse impedance model.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE049

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE050

Transverse Impedance Model of the CERN-PSB

impedance, space-charge, kicker, simulation

406

C. Zannini, G. Iadarola, K.S.B. Li, T.L. Rijoff, G. Rumolo
CERN, Geneva, Switzerland
B. Jones
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
T.L. Rijoff
TU Darmstadt, Darmstadt, Germany

In the framework of the PS-Booster upgrade project an accurate impedance model is needed in order to determine the effect on the beam stability and assess the impact of the new devices before installation in the machine. This paper describes the PSB impedance model which includes resistive wall, indirect space charge, flanges, step transitions, ejection kicker including cables, injection kickers and cavities. Each impedance contribution has been computed for different energies in the PSB cycle. Measurements of the coherent tune shifts have been performed and compared to calculations based on the impedance model.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE050

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE064

Beam Impedance Optimization of the TOTEM Roman Pots

impedance, detector, simulation, cavity

452

N. Minafra
CERN, Geneva, Switzerland

The TOTEM experiment has been designed to measure the total proton-proton cross section and to study elastic and diffractive scattering at the LHC energy. The measurement requires detecting protons at distances as small as 1 mm from the beam center: TOTEM uses Roman Pots (RP), special beam pipe insertions, to move silicon detectors close to the beams to detect particles very near the beam axis. In the first period of running of the LHC no problems were detected with retracted Roman Pots and during insertions in special runs; however, during close insertions to highest intensity beam, impedance heating has been observed. After the LS1 the LHC beam current will increase and the equipment that can interact with the beam needed to be optimized. A new RP, optimized to minimize the beam coupling, has been designed with the help of CST Particle Studio; a prototype has been used to test the simulation results in the laboratory with wire and probe measurements. Furthermore, in both the old and the new RPs, new ferrites have been installed. The new ferrite material has a higher Curie temperature than the one used before LS1 and a thermal treatment at 1000°C has been applied to reduce the out-gassing.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE064

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE070

Reduction of Electron Cloud in Particle Accelerator Beampipes Studied by RF Multipacting

electron, injection, detector, network

472

R. Leber, F. Caspers, P. Costa Pinto, M. Taborelli
CERN, Geneva, Switzerland

For a given beam structure, chamber geometry and magnetic field configuration, the electron cloud (EC) intensity depends on the Secondary Electron Yield (SEY) of the beam pipe. The reduction of the EC density as a function of machine operation time (scrubbing) is attributed to the growth of a low SEY carbon film induced by electron bombardment. In this paper, we study the time evolution of the conditioning of stainless steel beam pipes in a laboratory setup. The EC or multipacting is induced by Radio-Frequency (RF) fields in a coaxial resonator under vacuum. Strip detectors are used to monitor the current of the EC. Induced pressure rise is simultaneously detected. The multipacting intensity shows a linear dependence on the positive DC bias voltage up to 1000 V, applied to the central electrode. An accelerated conditioning is observed for the applied bias voltage. The SEY of samples exposed to the EC is measured and the surface composition is monitored by X-ray Photoelectron Spectroscopy. The measured SEY, surface composition and multipacting behaviour are well correlated. The injection of acetylene and dodecane during multipacting proved to be ineffective in the conditioning.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE070

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA005

Non-invasive Beam Profile Monitoring

detector, operation, ion, proton

537

C.P. Welsch, T. Cybulski, A. Jeff, V. Tzoganis, H.D. Zhang
Cockcroft Institute, Warrington, Cheshire, United Kingdom
T. Cybulski, A. Jeff, V. Tzoganis, C.P. Welsch, H.D. Zhang
The University of Liverpool, Liverpool, United Kingdom
A. Jeff
CERN, Geneva, Switzerland
V. Tzoganis
RIKEN, Saitama, Japan

Funding: Work supported by the Helmholtz Association under contract VH-NG-328, the EU under contracts 215080 and 289485, as well as the STFC Cockcroft core grant No. ST/G008248/1.
State-of-the-art high energy and high intensity accelerators require new approaches to transverse beam profile monitoring as many established techniques will no longer work due to the high power stored in the beam. In addition, many accelerator applications such as ion beam cancer therapy or material irradiation would benefit significantly from the availability of non-invasive beam profile monitors. Research in the QUASAR Group has focused on this area over the past 5 years. Two different approaches were successfully developed: Firstly, a supersonic gas jet-based monitor was designed and commissioned. It enables the detection of the 2-dimensional transverse beam profile of essentially any charged particle beam with negligible disturbance of the primary beam and accelerator vacuum. Secondly, a monitor based on the Silicon strip VELO detector, originally developed for the LHCb experiment, was tested as an online beam monitor at the Clatterbridge Cancer Center in the UK. The design of both monitors is presented in this contribution. Results from measurements are discussed and complemented by numerical studies into the performance limits of either technique.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA005

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA008

Simulation of Gas-Scattering Lifetime using Position- and Species-Dependent Pressure and Aperture Profiles

scattering, simulation, storage-ring, photon

546

M. Borland, J.A. Carter, H. Cease, B.K. Stillwell
ANL, Argonne, Ilinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
When computing gas-scattering lifetime for storage rings, it is common to use the average pressure, even though it is known that the pressure varies with location in the ring and varies differently for different gas species. In addition, other simplifications are commonly made, such as assuming that the apertures in the horizontal and vertical planes are independent and assuming that the momentum acceptance can be characterized by a single value. In this paper, we describe computation of the elastic- and bremsstrahlung-scattering lifetimes that includes species-specific gas pressure profiles computed with VACCALC and MOLFLOW. In addition, the computations make use of the detailed shape of the dynamic acceptance and the position-dependent momentum acceptance. Comparisons are made to simpler methods for the Advanced Photon Source storage ring and the multi-bend achromat upgrade lattice.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA008

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA027

Electron Cloud Measurements in Fermilab Main Injector and Recycler

electron, proton, injection, operation

604

J.S. Eldred
Indiana University, Bloomington, Indiana, USA
M. Backfish, J.S. Eldred, C.-Y. Tan, R.M. Zwaska
Fermilab, Batavia, Illinois, USA

This conference paper presents a series of electron cloud measurements in the Fermilab Main Injector and Recycler. A new instability was observed in the Recycler in July 2014 that generates a fast transverse excitation in the first high intensity batch to be injected. Microwave measurements of electron cloud in the Recycler show a corresponding dependence on the batch injection pattern. These electron cloud measurements are compared to those made with a retarding field analyzer (RFA) installed in a field-free region of the Recycler in November. RFAs are also used in the Main Injector to evaluate the performance of beampipe coatings for the mitigation of electron cloud. Contamination from an unexpected vacuum leak revealed a potential vulnerability in the amorphous carbon beampipe coating. The diamond-like carbon coating, in contrast, reduced the electron cloud signal to 1\% of that measured in uncoated stainless steel beampipe.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA027

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA033

Modeling Electron Emission and Surface Effects from Diamond Cathodes

electron, simulation, cathode, scattering

620

D.A. Dimitrov, J.R. Cary, D.N. Smithe, C.D. Zhou
Tech-X, Boulder, Colorado, USA
I. Ben-Zvi, T. Rao, J. Smedley, E. Wang
BNL, Upton, Long Island, New York, USA

Funding: We are grateful to the U.S. DoE Office of Basic Energy Sciences for supporting this work under grants DE-SC0006246 and DE-SC0007577.
We developed modeling capabilities, within the Vorpal particle-in-cell code, for three-dimensional (3D) simulations of surface effects and electron emission from semiconductor photocathodes. They include calculation of emission probabilities using general, piece-wise continuous, space-time dependent surface potentials, effective mass and band bending field effects. We applied these models, in combination with previously implemented capabilities for modeling charge generation and transport in diamond, to investigate the emission dependence on applied electric field in the range from approximately 2 to 17 MV/m along the [100] direction. The simulation results were compared to experimental data when using different emission models, band bending effects, and surface-dependent electron affinity. Simulations using surface patches with different levels of hydrogenation lead to the closest agreement with the experimental data.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA033

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA039

Secondary Electron Yield Measurement and Electron Cloud Simulation at Fermilab

electron, simulation, proton, dipole

629

Y. Ji
IIT, Chicago, Illinois, USA
L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA
R.M. Zwaska
Fermilab, Batavia, Illinois, USA

Funding: This work was funded by the National Science Foundation under the grant no. 1205811.
Fermilab Main Injector is upgrading the accelerator to double the beam intensity from 24·10¹² protons to 48·10¹² protons, which brings the accelerator into a regime where electron cloud effects may limit the accelerator performance. In fact, an instability that could be caused by electron cloud effects has already been observed in the Recycler. Secondary Electron Yield (SEY) is an important property of the vacuum chamber material that has great influence on the process of building up free electrons. The Main Injector of the Fermilab accelerator complex offers the opportunity to measure SEY and conditioning effects in the environment of a running accelerator, since samples of these materials are located at the beampipe wall. The SEY of stainless steel (SS316L) and TiN coated SS316L in the proximity of the proton beam were measured and compared. A series of simulation studies of electron cloud build up were done for the Main Injector and Recycler using the code POSINST. Parametric studies were done to determine the maximum electron density vs. peak SEY at different beam intensities in the Fermilab Main Injector. Threshold simulations of electron cloud density verus SEY were extended from Main Injector to include the Recycler Ring. It was found that the electron cloud density around the beam depends on bunch location within the bunch train.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA039

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA060

Impedance Measurement for the SPEAR3 Storage Ring

impedance, lattice, storage-ring, damping

694

X. Huang, J.J. Sebek
SLAC, Menlo Park, California, USA

We studied the transverse impedance of the SPEAR3 storage ring with tune shift vs. beam intensity, head-tail instability and transverse mode coupling instability measurements. By taking measurements under different machine conditions, we probed the frequency dependence of the impedance, from which an impedance model was built. This model is consistent with instability measurements and previous bunch lengthening results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA060

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMN010

Non-linear Magnetic Inserts for the Integrable Optics Test Accelerator

alignment, optics, dipole, quadrupole

724

F.H. O'Shea, R.B. Agustsson, Y.C. Chen, E. Spranza
RadiaBeam, Santa Monica, California, USA
D.W. Martin, J.D. McNevin
RadiaBeam Systems, Santa Monica, California, USA

We present here a status update of the manufacture and magnetic measurements of the non-linear inserts for the Integrable Optics Test Accelerator. RadiaBeam Technologies is designing the 2-meter structure from magnetic field specifications, including pole design, measurement systems and alignment fiducialization. Herein, we will describe the current state of the project.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMN010

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMN021

NSLS-II Storage Ring BPM Button Development

impedance, simulation, multipole, storage-ring

748

A. Blednykh, B. Bacha, G. Bassi, W.X. Cheng, C. Hetzel, B.N. Kosciuk, D. Padrazo, O. Singh
BNL, Upton, Long Island, New York, USA

Funding: Work supported by DOE contract DE-AC02-98CH10886
The NSLS-II BPM Button design and its development process have been described. Subjects discussed include BPM Button impedance optimization, design and construction, production, BPM Button selection and a first temperature measurements at 200mA average current within 1200 bunches.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMN021

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMN025

Local Impedance Estimation of NSLS-II Storage Ring with Bumped Orbit

impedance, closed-orbit, wiggler, damping

754

J. Choi, G. Bassi, A. Blednykh, Y. Hidaka
BNL, Upton, Long Island, New York, USA

Funding: DOE contract No: DE-AC02- 98CH10886
As the newly constructed 3rd generation light source, NSLS-II is expected to provide the synchrotron radiation of ultra high brightness and flux with advanced insertion devices. To minimize the beam emittance, damping wigglers are used and the small aperture is located at the straight section with the damping wiggler and the corresponding vacuum camber is NEG coated. We used the local bump method to find the effect on the beam from the narrow aperture and the paper shows the results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMN025

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPHA008

Investigation of Beam Halo Using In Vacuum Diamond Sensor at ATF2

electron, pick-up, controls, laser

791

S. Liu, P. Bambade, F. Bogard, P. Cornebise, V. Kubytskyi, C. Sylvia
LAL, Orsay, France
A. Faus-Golfe, N. Fuster-Martínez
IFIC, Valencia, Spain
T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan
T. Tauchi, N. Terunuma
Sokendai, Ibaraki, Japan

Funding: Chinese Scholarship Council, CNRS and P2IO LABEX
Beam halo transverse distribution measurements are of great importance for the understanding of background sources of the nano-meter beam size monitor at the interaction point (IPBSM) of ATF2. One of the most critical issues for the beam halo measurement is to reach high dynamic range. Two in vacuum diamond sensor beam halo scanners (DSv) with four strips each have been developed for the investigation of beam halo transverse distributions at ATF2. The first DSv was installed for horizontal beam halo scanning after the interaction point (IP) of ATF2, in Nov. 2014. It aims to measure the beam halo distribution with large dynamic range (~10⁶), and investigate the possibility of probing the Compton recoil electrons produced in the interaction with the IPBSM laser beams. Studies to characterize the DS performance and measurements of horizontal beam halo performed in Nov.-Dec. 2014 are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA008

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPHA013

Superconducting Radio Frequency Cavity Degradation Due to Errant Beam

cavity, ion, ion-source, linac

805

C.C. Peters, D. Curry, G.D. Johns
ORNL RAD, Oak Ridge, Tennessee, USA
A.V. Aleksandrov, W. Blokland, M.T. Crofford, C. Deibele, G.W. Dodson, J. Galambos, T.A. Justice, S.-H. Kim, T.A. Pelaia II, M.A. Plum, A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05- 00OR22725 for the U.S. Department of Energy.
In 2009, the Superconducting Radio Frequency (SRF) cavities at the Spallation Neutron Source (SNS) began to experience significant operational degradation [1]. The source of the degradation was found to be repeated striking of cavity surfaces with errant beam pulses. The Machine Protection System (MPS) was designed to turn the beam off during a fault condition in less than 20 μseconds [2] as these errant beam pulses were not unexpected. Unfortunately an improperly operating MPS was not turning off the beam within the designed 20 μseconds, and the SRF cavities were being damaged. The MPS issues were corrected, and the SRF performance was restored with cavity thermal cycling and RF processing. However, the SRF cavity performance has continued to degrade, though at a reduced rate compared to 2009. This paper will detail further study of errant beam frequency, amount lost per event, causes, and the corrective actions imposed since the initial event.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA013

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPHA049

Evolution of Diagnostics and Services of the DAΦNE Beam Test Facility

detector, linac, controls, diagnostics

904

L.G. Foggetta, B. Buonomo
INFN/LNF, Frascati (Roma), Italy
P. Valente
INFN-Roma, Roma, Italy

The DAΦNE Beam Test Facility (BTF) is operational in Frascati since 2003. In the last years the beam diagnostics tools have been completely renewed and the services for users have been largely improved. We describe here the new transverse beam diagnostics based on new GEM TPC detectors and Timepix/FitPix, the new BTF network layout, the renewed DAQ system including the BCM detectors, the data caching system based on MEMCached and the integration of the new sub-systems in the new data-logging. All other services, such as the environmental monitoring system, vacuum system, payload remote handling, and gas distribution have been also improved.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA049

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPHA051

Scintillating Fibers used as Profile Monitors for the CNAO HEBT Lines

detector, proton, ion, extraction

910

E. Rojatti
UniPV, Pavia, Italy
J. Bosser, M. Haguenauer, P. Poilleux
CERN, Geneva, Switzerland
J. Bosser, G.M.A. Calvi, L. Lanzavecchia, A. Parravicini, M. Pullia, C. Viviani
CNAO Foundation, Milan, Italy
M. Caldara
University of Bergamo, Bergamo, Italy

The CNAO (Centro Nazionale di Adroterapia Oncologica) Foundation is the first Italian center for deep hadrontherapy with Protons and Carbon Ions. Several beam monitors exploiting the scintillation process have been designed to check the beam quality in the extraction lines, in order to guarantee patients safety. The SFH (Scintillating Fibers Harp), the QPM (Qualification Profile Monitor), and the SFP (Scintillating Fibers plus Photodiodes) are made up by two orthogonal scintillating fibers harps with not dead area for the horizontal and the vertical beam profiles measurement. The QPM and the SFH are both installed on the beam line and they use a CCD camera for the signal acquisition. The SFP is a SFH upgrade project aimed to replace the camera with two Photodiodes arrays coupled to the fibers in vacuum. The WD (Watch Dog) detector, not already installed, has been designed to check the beam position through the intensity of the beam tails. It uses two couples of scintillating fibers displaced transversally to the beam direction, coupled to four APDs (Avalanche Photodiodes). This work describes the beam detectors, their achieved performances and the most recent beam measurements.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA051

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPHA054

Interaction Point Orbit Feedback System at SuperKEKB

feedback, luminosity, quadrupole, simulation

921

Y. Funakoshi, H. Fukuma, T. Kawamoto, M. Masuzawa, T. Oki, S. Uehara, H. Yamaoka
KEK, Ibaraki, Japan
S.D. Anderson, S.M. Gierman, M. Kosovsky, J.T. Seeman, C.M. Spencer, M.K. Sullivan, O. Turgut, U. Wienands
SLAC, Menlo Park, California, USA
P. Bambade, D. El Khechen, D. Jehanno, V. Kubytskyi, C. Rimbault
LAL, Orsay, France

In order to maintain an optimum beam collision condition in a double ring collider such as SuperKEKB it is essential to have an orbit feedback system at the interaction point (IP). We have designed such a system based on experiences at KEKB and PEP-II. For the vertical offset and crossing angle, we will rely on the system based on the beam orbit measurement similar to that used at KEKB. For the horizontal offset, however, we will utilize the dithering system which was successfully used at PEP-II, because the horizontal beam-beam kick is very weak with the "nano-beam scheme". Some hardware devices have been already fabricated and others are in preparation. The present status of the development is reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA054

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPTY011

Operation Experience of p-Carbon Polarimeter in RHIC

target, polarization, detector, operation

956

H. Huang, E.C. Aschenauer, G. Atoian, A. Bazilevsky, O. Eyser, D. Kalinkin, J. Kewisch, Y. Makdisi, S. Nemesure, A. Poblaguev, W.B. Schmidke, D. Smirnov, D. Steski, K. Yip, A. Zelenski
BNL, Upton, Long Island, New York, USA
I.G. Alekseev, D. Svirida
ITEP, Moscow, Russia

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The spin physics program in Relativistic Heavy Ion Collider (RHIC) requires fast polarimeter to monitor the polarization evolution on the ramp and during stores. Over past decade, the polarimeter has evolved greatly to improve its performance. These include dual chamber design, monitoring camera, Si detector selection (and orientation), target quality control, and target frame modification. The preamp boards have been modified to deal with the high rate problem, too. The ultra thin carbon target lifetime is a concern. Simulations have been carried out on the target interaction with beam. Modification has also been done on the frame design. Extra caution has been put on RF shielding to deal with the pickup noises from the nearby stochastic cooling kickers. This paper summarizes the recent operation performance of this delicate device.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY011

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPTY030

Capacitive Linear-Cut Beam Position Monitor Design for Ion Synchrotron at KHIMA Project

synchrotron, target, operation, proton

998

J.G. Hwang, C.H. Kim, S.H. Nam, S.Y. Noh
KIRAMS/KHIMA, Seoul, Republic of Korea
G. Hahn, W.T. Hwang, T.K. Yang
KIRAMS, Seoul, Republic of Korea
E.-S. Kim
Kyungpook National University, Daegu, Republic of Korea

The KHIMA (Korea Heavy Ion Medical Accelerator) project is launched to construct the carbon and proton beam base ion therapy machine. It, which consists of the injector with RFQ and IH-DTL linacs, medium beam transport line, synchrotron, and high energy beam transport line, will be provided the carbon beam up to 430 MeV/u and proton beam up to 230 MeV for cancer therapy. The high precision beam position monitor is required to match and control the beam trajectory for the beam injection and closed orbit in synchrotron. It was also used for measuring the beta-function, tune, and chromaticity. Since the bunch length at heavy ion synchrotron is relatively long, a few meters, a box-like device with long plates of typically 20 cm is used to enhance the signal strength and to get a precise linear dependence with respect to the beam displacement. In this presentation, we show the electromagnetic design of the electrode and surroundings to satisfy the resolution of 100 um, the criteria for mechanical aspect to satisfy the position accuracy of 200 um, the measurement result of position accuracy by using the wire test-bench, and the beam-test results with long (~ 1.6 us) electron beam in PAL.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY030

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPTY033

Fast Kicker

kicker, impedance, simulation, magnet-design

1001

V.V. Gambaryan, A.A. Starostenko
BINP SB RAS, Novosibirsk, Russia

Pulsed deflecting magnet project was worked out in BINP. The kicker design task is: impulsive force value is 1 mT*m, pulse edge is 5 ns, and impulse duration is about 200 ns. The unconventional approach to kicker design was offered. The possibility for set of wires using instead of plates using is considered. This approach allows us to reduce the effective plate surface. In this case we can decrease effects related to induced charges and currents. In the result of modelling optimal construction was developed. It includes 6 wires. The magnet aperture is about 5 cm. Calculated field rise time (about 1.5 ns) satisfies the conditions. Induced current effect reducing idea was confirmed. For configuration with 3 wires pair (with cross section of 2 mm) induced current in one wire is about 10% and in the wall is about 40%. However for design with plates current is about 40% and 20% respectively. Obtained magnet construction allows controlling of high field homogeneity by changing currents magnitudes in wires. In general we demonstrated the method of field optimization. Optimal kicker design was obtained. Wires using idea was substantiated.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY033

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPTY036

Radiation of a Bunch Moving in the Presence of a Bounded Planar Wire Structure

radiation, diagnostics, electronics, electromagnetic-fields

1007

V.V. Vorobev, S.N. Galyamin, A.A. Grigoreva, A.V. Tyukhtin
Saint-Petersburg State University, Saint-Petersburg, Russia

Three-dimensional* and planar** periodic structures can be used for non-destructive diagnostics of charged particle bunches. Here we consider the semi-infinite planar structure comprised of thin conducting parallel wires. If the period of the structure is much less than the typical wavelength of the electromagnetic field, then the structure's influence can be described with help of the averaged boundary conditions***. We study radiation of a charged particle bunch with small transversal size and arbitrary longitudinal one in two cases: (i) the bunch moves orthogonally to the grid at some distance from the edge and (ii) it moves along the edge of the grid. The problems are solved analytically. In both cases the bunch generates a surface wave which contains the information about the size of the bunch. The shape of the surface waves is similar to the radiation generated in the presence of 3D periodical wire structures*, however planar structure is simpler for use in accelerating system. Some typical numerical results for bunches of various shapes are given.
* V.V. Vorobev et al., Phys. Rev. Let., 108, 184801 (2012);
** A.V. Tyukhtin et al., Phys. Rev. ST AB (in press).
*** M.I. Kontorovich et al., Electrodynamics of Grid Structures (Moscow, 1987).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY036

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPTY063

The Flexible Customized Supervisor and Control System for Utility in TPS

controls, network, operation, monitoring

1085

C.S. Chen, W.S. Chan, J.-C. Chang, Y.C. Chang, Y.-C. Chung, C.W. Hsu, C.Y. Liu, Z.-D. Tsai
NSRRC, Hsinchu, Taiwan

In order to maintain and operate a synchrotron radiation light source well requires quite a few efforts. All parts of the big machine, including vacuum system, all kinds of magnets, RF facility, cryogenic equipments, radiation security, optic devices and utility equipment must cooperate in harmony to provide high quality light. Any one of the above system contains lots of analog or digital signal transmission, not to mention the vast range of utility. Numbers of programmable automation controllers (PACs) are applied in utility system in TPS to ensure the utility operates normally. In addition to the high reliability and distribution, the flexible programmability of PAC is the most critical feature in this project. A well-designed program, Archive Viewer, provides a platform for showing these big data from all distributed systems. The architecture of the server system for utility is described in this paper as well.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY063

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWI006

Development of a Supersonic Gas-jet Monitor to Measure Beam Profile Non-destructively

ion, electron, storage-ring, experiment

1157

H.D. Zhang, A. Jeff, V. Tzoganis, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
A. Jeff
CERN, Geneva, Switzerland
A. Jeff, V. Tzoganis, C.P. Welsch, H.D. Zhang
The University of Liverpool, Liverpool, United Kingdom
V. Tzoganis
RIKEN, Saitama, Japan

Funding: This project is supported by Helmholtz Association(VH-NG-328), EU’s 7th Framework Program for research, technological development and demonstration( 215080) and STFC Cockcroft core grant(ST/G008248/1).
The measurement of the transverse beam profile is a great challenge for high intensity, high brightness and high power particle beams due to their destructive power. Current non-destructive methods such as residual gas monitors and beam induced fluorescence monitors either require a rather long integration time or residual gas pressures in the order of 10^-7 mbar to make meaningful measurements. A supersonic gas-jet beam profile monitor has been developed by QUASAR group at the Cockcroft Institute, UK and promises significant improvements over these established techniques. In this monitor, a supersonic gas curtain is generated that crosses the beam to be analyzed under an angle of 45°. When both beams interact, ionization of the gas jet particles occurs and these ions are then accelerated by an electrostatic extraction field towards a Micro Channel Plate (MCP). Beam images are then obtained via a phosphor screen-CCD camera combination. In this contribution, we discuss the monitor design and present beam profile measurements of a 5 keV electron beam. These are complemented by results from measurements using a pulsed valve to study the gas jet dynamics.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI006

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWI009

A Multi-pinhole Faraday Cup Device for Measurement of Discrete Charge Distribution of Heavy and Light Ions

ion, electron, diagnostics, experiment

1160

P.K. Roy, S. Dwaraknath, F.U. Naab, S. Taller, O.F. Toader, G. Was
NERS-UM, Ann Arbor, Michigan, USA

It is a difficult task to identify the beam density distribution profile over discrete areas using a standard Faraday cup, as the measurements are provided for the full aperture geometry of the instrument. Ideally, the intensity of the scintillating material would provide a correlation to the beam density, but the low photon efficiency, damage to the scintillator, and camera resolution all limit the practicality of using this system for assessing the spatial resolution of an ion beam. A beam profile monitor (BPM) device has the ability to provide a partial or discrete distribution of an integrated beam profile. The BPM, however, does not discriminate between ions and electrons, the latter of which can be problematic for assessing the full beam profile. To provide a better description of the beam density in spatial dimensions, a multi-pinhole Faraday cup (MPFC) has been designed, developed, and applied to the measurement of energetic ions. This device uses an array of millimeter sized Faraday cups arranged in a grid to measure the current of the beam at discrete locations. This report presents the design of the device, and its performance with ion beams.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI009

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWI010

Design and Development of a Beam Stablity Mechanical Motion System Diagnostic for the APS MBA Upgrade

detector, insertion, insertion-device, ground-motion

1164

R.M. Lill, G. Decker, N. Sereno, B.X. Yang
ANL, Argonne, Ilinois, USA

Funding: Results shown in this report result from work performed at Argonne National Laboratory operated by UChicago Argonne, LLC, for the U.S. Department of Energy under contract DE-AC02-06CH11357.
The Advanced Photon Source (APS) is currently in the conceptual design phase for the MBA lattice upgrade. In order to achieve long-term beam stability goals, a Mechanical Motion System (MMS) has been designed to monitor critical in-tunnel beam position monitoring devices. The mechanical motion generated from changes in chamber cooling water temperature, tunnel air temperature, beam current and undulator gap positon causes erroneous changes in beam position measurements causing drift in the X-ray beam position. The MMS has been prototyped and presently provides critical information on the vacuum chamber and BPM support systems. We report on first results of the prototype system installed in the APS storage ring.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI010

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWI012

Conceptual Design and Analysis of a Storage Ring Beam Position Monitor for the APS Upgrade

operation, simulation, alignment, impedance

1170

B.K. Stillwell, R.M. Lill, R.R. Lindberg, M.M. O'Neill, B.G. Rocke, X. Sun
ANL, Argonne, Ilinois, USA
A. Blednykh
BNL, Upton, Long Island, New York, USA

Funding: Created by UChicago Argonne, LLC, operator of Argonne National Laboratory, a U.S. Department of Energy Office of Science laboratory operated under Contract No. DE-AC02-06CH11357.
A conceptual design has been developed for a radio frequency (rf) pickup-type beam position monitor (BPM) for use in a multi-bend achromat (MBA) storage ring under consideration by the APS Upgrade project (APS-U). Beam feedback systems are expected to require fourteen rf BPMs per sector with exceptional sensitivity and mechanical stability. Simultaneously, BPM insertion length must be minimized to allow lattice designers the greatest freedom in selecting magnet lengths and locations. Envisioned is a conventional four probe arrangement integrated inside of a pair of rf-shielded bellows for mechanical isolation. Basic aspects of the design are presented along with the results of analyses which establish expected mechanical, electronic, and beam physics-related performance measures.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUXC2

Engineering Challenges of Future Light Sources

storage-ring, feedback, emittance, synchrotron

1308

R.T. Neuenschwander, L. Liu, S.R. Marques, A.R.D. Rodrigues, R.M. Seraphim
LNLS, Campinas, Brazil

We review some of the present engineering challenges associated with the design and construction of ultra-low emittance storage rings, the 4th generation storage rings (4GSR). The field is experiencing a growing interest since MAX-IV, followed by Sirius, started to build storage rings based on multi-bend-achromat (MBA) lattices. It was the recent progress in accelerator technology that allowed these facilities to base their designs on this kind of lattice. Although the challenges are starting to be overcome, many issues are still open and a lot of R&D is required until the 4GSR achieve optimal performance.

Slides TUXC2 [7.022 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUXC2

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUAB2

First Collective Effects Measurements in NSLS-II with ID's

impedance, lattice, quadrupole, storage-ring

1332

A. Blednykh, B. Bacha, G. Bassi, W.X. Cheng, J. Choi, Y. Hidaka, Y. Li, B. Podobedov, T.V. Shaftan, V. Smalyuk, T. Tanabe, G.M. Wang, F.J. Willeke, L.-H. Yu
BNL, Upton, Long Island, New York, USA

Funding: Work supported by DOE contract DE-AC02-98CH10886.
As another important milestone towards the final goal to store an average current of 500mA, the average current of 200mA, distributed within ~1000 bunches, was recently achieved in the NSLS-II storage ring after the installation of three Damping Wigglers and four In-Vacuum Undulators. First measurements of the collective effects and instability thresholds, both in single- and multi-bunch mode, are discussed.

Slides TUAB2 [2.691 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUAB2

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUAD1

Magnet Design and Control of Field Quality for TPS Booster and Storage Rings

quadrupole, dipole, sextupole, multipole

1370

J.C. Jan, C.H. Chang, C.-T. Chen, H.H. Chen, Y.L. Chu, M.-H. Huang, C.-S. Hwang, C.Y. Kuo, F.-Y. Lin, G.-H. Luo, I.C. Sheng, C.S. Yang, Y.T. Yu
NSRRC, Hsinchu, Taiwan

High-quality and very demanding magnets were designed, fabricated, field quality controlled and installed in the Taiwan Photon Source (TPS). The Storage Ring (SR) lattice is based on double-bend achromat structure with 1.6 nm-rad emittance and slight dispersion in straight sections. The fabrication and field measurement of these magnets were completed in Oct. 2013. The first synchrotron light from TPS storage ring, without applying any corrector at 3 GeV, was observed on Dec. 31, 2014. It indicates that the profile precision and field quality of magnets, and girders alignment reach world class standard. The integral multipoles components of the 240 SR quadrupole and 168 SR sextupole magnets conform to strict specifications. The maximum offset of measured mechanical center in magnets is better than 0.01 mm after feet shimming. The magnetic center offset of the magnets is within 0.02 mm inspected by rotating-coil method. The magnets’ field quality of booster’s pure quadrupole and combined-function quadrupole were accepted according to the errors specifications from beam dynamics and also in the beam commissioning. A permeability study of vacuum chamber was implemented during the booster ring hardware testing. The magnetic field of magnets is distorted by the permeability of vacuum chamber. Study of multipole errors due to magnetized vacuum chamber inside the magnet will be discussed.

Slides TUAD1 [2.698 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUAD1

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWA006

SIRIUS ACCELERATORS STATUS REPORT

storage-ring, booster, dipole, quadrupole

1403

A.R.D. Rodrigues, F.C. Arroyo, O.R. Bagnato, J.F. Citadini, R.H.A. Farias, J.G.R.S. Franco, L. Liu, S.R. Marques, R.T. Neuenschwander, C. Rodrigues, R.M. Seraphim, O.H.V. Silva
LNLS, Campinas, Brazil

Sirius is a 3 GeV synchrotron light source that is being built by the Brazilian Synchrotron Light Laboratory (LNLS). The electron storage ring is based on a modified 5BA cell to achieve a bare lattice emittance of 0.27 nm.rad in a 518 m circumference ring that contains 20 straight sections of alternating 6 and 7 meters in length. The 5BA cell accommodates a thin permanent magnet high field (2 T) dipole in the center of the middle bend producing hard X-ray radiation (εc=12 keV) with a modest contribution to the total energy loss. In this paper we discuss the main achievements and issues for Sirius accelerators. Developments in beamlines are not discussed here.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA006

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWA012

SOLEIL Status Report

undulator, operation, photon, storage-ring

1419

A. Nadji, Y.-M. Abiven, F. Bouvet, P. Brunelle, A. Buteau, N. Béchu, L. Cassinari, M.-E. Couprie, X. Delétoille, C. Herbeaux, N. Hubert, N. Jobert, M. Labat, J.-F. Lamarre, P. Lebasque, A. Lestrade, A. Loulergue, P. Marchand, O. Marcouillé, J.L. Marlats, L.S. Nadolski, R. Nagaoka, P. Prigent, K.T. Tavakoli, M.-A. Tordeux, M. Valléau
SOLEIL, Gif-sur-Yvette, France

The 2.75 GeV synchrotron light source SOLEIL (France) delivers photons to 27 beamlines and 2 new ones are under construction. The commissioning of the Femtoslicing operation mode involving two beamlines is in progress. The uniform filling pattern is now available to users with a 500 mA stored beam current. The operation of the two canted and long beamlines ANATOMIX and Nanoscopium both using in-vacuum insertion devices (IDs) as a photon source has been raising challenges still under investigation. Upgrades of crucial subsystem equipment like magnet power supplies, storage ring RF input power couplers, and solid state amplifiers are continuing. New user requests for beam stability are under upgrade consideration. Other projects for the storage ring are ongoing such as the design and construction of new insertion devices, new multipole injection kicker, localised small and round photon beam production, as well as R&D on 500 MHz solid-state amplifiers. In parallel first studies for a future upgrade of the machine have been progressing.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWA016

Modeling of beam losses at ESRF

scattering, simulation, electron, detector

1430

R. Versteegen, P. Berkvens, N. Carmignani, J. Chavanne, L. Farvacque, S.M. Liuzzo, B. Nash, T.P. Perron, P. Raimondi, K.B. Scheidt, S.M. White
ESRF, Grenoble, France

As the ESRF enters the second phase of its upgrade towards ultra low emittance, the knowledge of the beam loss pattern around the storage ring is needed for radiation safety calculations and for the new machine design optimization. A model has been developed to simulate the Touschek scattering and the scattering of electrons on residual gas nuclei in view of producing a detailed loss map of the machine. Results of simulation for the ESRF are presented and compared with real beam measurements.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA016

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWA025

Beam Heat Load Analysis with COLDDIAG: A Cold Vacuum Chamber for Diagnostics

electron, storage-ring, diagnostics, synchrotron

1459

R. Voutta, S. Casalbuoni, S. Gerstl, A.W. Grau, T. Holubek, D. Saez de Jauregui
KIT, Eggenstein-Leopoldshafen, Germany
R. Bartolini, M.P. Cox, E.C. Longhi, G. Rehm, J.C. Schouten, R.P. Walker
DLS, Oxfordshire, United Kingdom
M. Migliorati, B. Spataro
INFN/LNF, Frascati (Roma), Italy

The knowledge of the heat intake from the electron beam is essential to design the cryogenic layout of superconducting insertion devices. With the aim of measuring the beam heat load to a cold bore and understanding the responsible mechanisms, a cold vacuum chamber for diagnostics (COLDDIAG) has been built. The instrumentation comprises temperature sensors, pressure gauges, mass spectrometers and retarding field analyzers, which allow to study the beam heat load and the influence of the cryosorbed gas layer. COLDDIAG was installed in the storage ring of the Diamond Light Source from September 2012 to August 2013. During this time measurements were performed for a wide range of machine conditions, employing the various measuring capabilities of the device. Here we report on the analysis of the measured beam heat load, pressure and gas content, as well as the low energy charged particle flux and spectrum as a function of the electron beam parameters.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA025

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWA044

Test electron source for increased brightness emission by near band gap photoemission

cathode, electron, emittance, simulation

1512

S. Friederich, K. Aulenbacher
IKP, Mainz, Germany

Funding: Bundesministerium für Bildung und Forschung/Federal Ministry of Education and Research; Joint project HOPE
A new photoemissive electron source is being built in order to make use of the reduction of ensemble temperature in near band gap photoemission. It will operate at up to 200 kV bias voltage with NEA GaAs photocathodes. High bunch charges will be investigated in pulsed mode with respect to the conservation of emittances at low energy excitations. High field gradients at the cathode surface will also allow further investigation of the field emission process of these photocathodes.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA044

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWA048

Radiative Cooled Target for the ILC Polarized Positron Source

target, positron, photon, radiation

1526

A. Ushakov
University of Hamburg, Hamburg, Germany
F. Dietrich, S. Riemann, T. Rublack
DESY Zeuthen, Zeuthen, Germany
P. Sievers
CERN, Geneva, Switzerland

Funding: Work supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Optimization", contract number 19XL7IC4
The target for the polarized positron source of the future International Linear Collider (ILC) is designed as wheel of 1 m diameter spinning with 2000 revolutions per minute to distribute the heat load. The target system is placed in vacuum since exit windows would not stand the load. In the current ILC design, the positron target is assumed to be water-cooled. Here, as an alternative, radiative cooling of the target has been studied. The energy deposition in the target is the input for ANSYS simulations. They include the temperature evolution as well as the corresponding thermo-mechanical stress in the target components. A principal design is suggested for further consideration.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA048

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWA062

GaAs Photocathode Activation with CsTe Thin Film

photon, electron, cathode, experiment

1567

M. Kuriki, Y. Seimiya, K. Uchida
HU/AdSM, Higashi-Hiroshima, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

Funding: This work is partly supported by MEXT/JSPS KAKENHI (Grant-in-Aid for scientific research) 24654054.
GaAs is an unique and advanced photocathode which can generate highly polarized and extremely low emittance electron beam. The photo-emission is possible up to 900nm wavelength. These advantages are due to NEA (Negative Electron Affinity) surface where the conduction band minimum is higher than the vacuum energy state. The NEA surface is artificially made with Cs-O/F evaporation on the cleaned GaAs surface, but the NEA surface is fragile, so that the emission is easily lost by poor vacuum environment and high emission density. NEA activation with any vital material is desirable. We found that the GaAs can be activated by CsTe thin film which is known as a vital photo-cathode material. The photo-electron emission spectrum extends up to 900 nm wavelength which corresponds to the band-gap energy of GaAs. The result strongly suggests that the surface becomes effectively NEA state by the CsTe thin film.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA062

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPJE010

Study of Cs-Te Photocathode for RF Electron Gun

electron, gun, radiation, scattering

1632

S. Matsuzaki, M. Nishida, K. Sakaue, M. Washio
Waseda University, Tokyo, Japan
H. Iijima
Tokyo University of Science, Tokyo, Japan

At Waseda University, we have been studying high quality electron beam with an rf electron gun. In recent accelerator study and application researches, high quality electron beam are strongly required. Photocathode is a key component to generate higher quality electron beam. Cs-Te photocathode shows high quantum efficiency (Q.E.) (~10%) and has long life time (~several months). From 2013, we built a photocathode evaporation chamber and started photocathode study. In this study, our purpose is to clarify their property and to establish an ideal evaporation recipe. We succeeded in producing high quality Cs-Te photocathode, and electron beam generated by our Cs-Te photocathode shows high charge (4.6nC/bunch) and high Q.E. (1.74%) in our rf electron gun. Furthermore, we found a Q.E. recovery after Cs deposition process and it causes higher Q.E. than usual due to, we believe, Cs deposition quantity or Cs deposition speed. Thus we are now surveying the optimum Cs evaporation parameters. In this conference, we will report a detail of our photocathode development system, the latest progress of optimization study of Cs-Te photocathode and future plans.
Work supported by Cooperative and Supporting Program for Researches and Educations in Universities and NEDO(New Energy and Industrial Technology Development Organization.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE010

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPJE036

A New Bench Concept for Measuring Magnetic Fields of Big Closed Structures

controls, operation, synchrotron, alignment

1690

J. Campmany, F. Becheri, C. Colldelram, J. Marcos, V. Massana, J. Nicolás, L. Ribó
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

The measurement of big closed magnetic structures is becoming a challenge of great interest. The main reason is the tendency towards building accelerators with high magnetic fields produced by small gap magnets, as well as the development of cryogenic or superconducting narrow-gap insertion devices. Usual approach, based on side-measurements made with a Hall probe mounted on the tip of a motorized arm based on a long granite bench is no more applicable to such closed structures. So, new concepts and approaches have been developed, mainly based on complex devices that insert a Hall probe inside the magnetic structure maintaining the desired position by close-loop controls. The main problem of these devices is that they are not general-purpose oriented: they need a special vacuum chamber, require a specific geometry of the magnetic structure, or does not provide 3D field-map measurements. We present in this paper a new bench that has been built at ALBA synchrotron that is simple, multi-purpose and can be a general solution for measuring big closed structures.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE036

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPJE039

Recent Results on the Performance of Cs3Sb Photocathodes in the PHIN RF-Gun

cathode, gun, laser, operation

1699

C. Heßler, E. Chevallay, S. Döbert, V. Fedosseev, I. Martini, M. Martyanov
CERN, Geneva, Switzerland

For the CLIC drive beam a photoinjector option is under study at CERN as an alternative to the thermionic electron gun in the CLIC baseline design. The CLIC drive beam requires a high bunch charge of 8.4 nC and 0.14 ms long trains with 2 ns bunch spacing, which is challenging for a photoinjector. In particular the required long and high intensity laser pulses cause a degradation of the beam quality during the frequency conversion process, which generates the ultra-violet laser beam needed for standard Cs2Te photocathodes. To overcome this issue Cs3Sb cathodes sensitive to green light have been studied at the high-charge PHIN photoinjector since a few years. In this paper recent measurements of fundamental properties of Cs3Sb photocathodes such as quantum efficiency, cathode lifetime and dark current from summer 2014 will be presented, and compared with previous measurements and with the performance of Cs2Te photocathodes.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE039

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPJE050

Design of a Resonant Transition Radiation Source in the soft X-ray Range

photon, radiation, electron, resonance

1735

P. Wang, K.C. Leou
NTHU, Hsinchu, Taiwan
N.Y. Huang, W.K. Lau, A.P. Lee
NSRRC, Hsinchu, Taiwan

Resonant transition radiation (RTR) can be generated from multi-layer structures when they are driven by relativistic electron beams. In consideration of using the NSRRC 90 MeV photoinjector as driver, we examined the feasibility of generating narrow-band soft x-rays from various multi-layer structures. Based on analytical theory, the expected angular-spectral distribution and photon yield of these radiators are calculated and compared.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE050

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPJE055

The Evolution of the Transverse Energy Distribution of Electrons from a GaAs Photocathode as a Function of its Degradation State

electron, detector, cathode, brightness

1748

L.B. Jones, B.L. Militsyn, T.C.Q. Noakes
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
H.E. Scheibler, A.S. Terekhov
ISP, Novosibirsk, Russia

The brightness of a photoelectron injector is fundamentally limited by the mean longitudinal and transverse energy distributions of the photoelectrons emitted from its photocathode, and is increased significantly if the mean values of these quantities are reduced. To address this, ASTeC constructed a Transverse Energy Spread Spectrometer (TESS)* – an experimental facility designed to measure these transverse and longitudinal energy distributions which can be used for III-V semiconductor, alkali antimonide/telluride and metal photocathode research. We present measurements showing evolution of the transverse energy distribution of electrons from GaAs photocathodes as a function of their degradation state. Photocathodes were activated to negative electron affinity in our photocathode preparation facility (PPF)** with quantum efficiency around 10.5%. They were then transferred to TESS under XHV conditions, and progressively degraded through controlled exposure to oxygen. Data has been collected under photocathode illumination at 635 nm, and demonstrates a constant relationship between energy distribution and the level of electron affinity.
* Proc. FEL ’13, TUPPS033, 290-293
** Proc. IPAC '10, TUPE095, 2347-2349, Proc. IPAC ’11, THPC129, 3185-3187

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE055

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPJE064

Calibration of Fast Fiber-Optic Beam Loss Monitors for the Advanced Photon Source Storage Ring Superconducting Undulators

undulator, photon, simulation, electron

1780

J.C. Dooling, K.C. Harkay, Y. Ivanyushenkov, V. Sajaev, A. Xiao
ANL, Argonne, Ilinois, USA
A. Vella
University of Illinois at Urbana-Champaign, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357.
We report on the calibration and use of fast fiber-optic (FO) beam loss monitors (BLMs) in the Advanced Photon Source storage ring (SR). A superconducting undulator prototype (SCU0) has been operating in SR Sector 6 since the beginning of CY2013, and another undulator SCU1 (a 1.1-m length undulator that is three times the length of SCU0) is scheduled for installation in Sector 1 in 2015. The SCU0 main coil often quenches during beam dumps. MARS simulations have shown that relatively small beam loss (<1 nC) can lead to temperature excursions sufficient to cause quenching when the SCU0 windings are near critical current. To characterize local beam losses, high-purity fused-silica FO cables were installed in Sector 6 next to the SCU0 cryostat and in Sector 1 where SCU1 will be installed. These BLMs aid in the search for operating modes that protect the SCU structures from beam-loss-induced quenching. In this paper, we describe the BLM calibration process that included deliberate beam dumps at locations of BLMs. We also compare beam dump events where SCU0 did and did not quench.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE064

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPJE078

Modeling of Impedance Effects for the APS-MBA Upgrade

impedance, wakefield, photon, simulation

1825

R.R. Lindberg
ANL, Argonne, Illinois, USA
A. Blednykh
BNL, Upton, Long Island, New York, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Understanding the sources of impedance is critical to accelerator design, and only becomes more important as vacuum chambers become smaller and closer to the electron beam. The multibend achromat upgrade at the Advanced Photon Source (APS) requires small, 22-mm diameter vacuum chambers and even smaller (6 mm) gaps for the insertion devices, so that both rf heating and wakefield-driven transverse instabilities become important concerns. We discuss modeling the primary sources of geometric impedance using the electromagnetic finite difference codes GdfidL and ECHO, and how these codes are influencing vacuum and accelerator component design.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE078

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPJE079

High Charge Development of the APS Injector for an MBA Upgrade

booster, impedance, ion, injection

1828

C. Yao, M. Borland, J.R. Calvey, K.C. Harkay, D. Horan, R.R. Lindberg, N. Sereno, H. Shang, X. Sun, J. Wang
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
The APS MBA (multi-bend achromat) upgrade storage ring will employ a “swap out” injection scheme and requires a single-bunch beam with up to 20 nC from the injector. The APS injector, which consists of a 450-MeV linac, a particle accumulator ring (PAR), and a 7-GeV synchrotron (Booster), was originally designed to provide up to 6 nC of beam charge. High charge injector study is part of the APS upgrade R&D that explores the capabilities and limitations of the injector through machine studies and simulations, and identifies necessary upgrades in order to meet the requirements of the MBA upgrade. In the past year we performed PAR and booster high charge studies, implemented new ramp correction of the booster rap supplies, explored non-linear chromatic correction of the booster, etc. This report presents the results and findings.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE079

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMA010

Development of a Field-Emission Type S-band RF-Gun System for High Brightness Electron Source Applications

cathode, gun, electron, emittance

1856

Y.-M. Shin
Northern Illinois University, DeKalb, Illinois, USA
N. Barov
Far-Tech, Inc., San Diego, California, USA
A.T. Green
Northern Illinois Univerity, Dekalb, Illinois, USA

Electron beams emitted from a cold cathode are thermally stable and mono-energetic with a small phase-space volume*. We have been developing a field-emission type RF-gun system for high brightness electron source applications, including electron scattering/diffraction and tunable coherent X-ray/THz generation. The system consists of a single-gap gun-cavity and an S-band klystron/modulator capable of powering the gun with up to 5.5 MW peak (PRR = 1 Hz, duration = 2.5 μs). The designed gun built with the symmetrised side-couplers has surface field on the cathode ranging 50 – 100 MV/m with 1.3 – 1.7 MW klystron-power and 1.2 field ratio (HFSS). ASTRA simulations also indicate that the gun produces the beam with transverse emittances of less than 1 mm-mrad with 10 – 20 pC bunch charge at 500 keV beam energy. Under the gun operating condition, particle tracking/PIC simulations (CST) show that a single-tip CNT field-emitter** produces short pulsed bunches (~ 1/10 RF-cycle) with small emittance ( 0.01 mm-mrad) and high peak current density ( 10,000 kA/cm²). After the gun is fully installed and commissioned, a CNT-tip cathode will be tested with RF-field emission.
* N. De Jonge, J.-M. Bonard, Phil. Trans. R. Soc. Lond. A 362, 2239 (2004)
** G. S. Bocharov, and A. V. Eletskii, Nanomaterials 3, 393 (2013)

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPMA010

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMA038

Observation of Significant Quantum Efficiency Enhancement from a Polarized Photocathode with Distributed Brag Reflector

laser, polarization, electron, cathode

1923

S. Zhang, M. Poelker, M.L. Stutzman
JLab, Newport News, Virginia, USA
Y. Chen, A. Moy
SVT Associates, Eden Prairie, Minnesota, USA

Funding: This project was supported by the U.S. DOE Basic Energy Sciences under contract No. DE-AC05-060R23177.
Polarized photocathodes with higher Quantum efficiency (QE) would help to reduce the technological challenge associated with producing polarized beams at milliampere levels, because less laser light would be required, which simplifies photocathode cooling requirements. And for a given amount of available laser power, higher QE would extend the photogun operating lifetime. The distributed Bragg reflector (DBR) concept was proposed to enhance the QE of strained-superlattice photocathodes by increasing the absorption of the incident photons using a Fabry-Perot cavity formed between the front surface of the photocathode and the substrate that includes a DBR, without compromising electron polarization. Here we present recent results showing QE enhancement of a GaAs/GaAsP strained-superlattice photocathode made with a DBR structure. Typically, a GaAs/GaAsP strained-superlattice photocathode without DBR provides a QE of 1%, at a laser wavelength corresponding to peak polarization. In comparison, the GaAs/GaAsP strained-superlattice photocathodes with DBR exhibited an enhancement of over 2 when the incident laser wavelength was tuned to meet the resonant condition for the Fabry-Perot resonator.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPMA038

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTY045

Interactions between Macroparticles and High-Energy Proton Beams

proton, electron, simulation, beam-losses

2112

S. Rowan, A. Apollonio, B. Auchmann, A. Lechner, O. Picha, W. Riegler, H. Schindler, R. Schmidt, F. Zimmermann
CERN, Geneva, Switzerland

A known threat to the availability of the LHC is the interaction of macroparticles (dust particles) with the LHC proton beam. At the foreseen beam energy of 6.5 TeV during Run 2, quench margins in the superconducting magnets will be 2-3 times lower, and beam losses due such interactions may result in magnet quenches. The study introduce an improved numerical model of such interactions, as well as Monte-Carlo simulations that give the probability that such events will result in a beam-dump during Run 2.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY045

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTY049

Protection of Superconducting Magnets in Case of Accidental Beam Losses during HL-LHC Injection

injection, simulation, kicker, shielding

2128

A. Lechner, M.J. Barnes, C. Bracco, B. Goddard, F.L. Maciariello, A. Perillo Marcone, N.V. Shetty, G.E. Steele, J.A. Uythoven, F.M. Velotti
CERN, Geneva, Switzerland
F.M. Velotti
EPFL, Lausanne, Switzerland

Funding: Research supported by the High Luminosity LHC project.
The LHC injection regions accommodate a system of beam-intercepting devices which protect superconducting magnets and other accelerator components in case of mis-steered injected beam or accidentally kicked stored beam, e.g. due to injection kicker or timing malfunctions. The brightness and intensity increase required by the High Luminosity (HL) upgrade of the LHC necessitates a redesign of some devices to improve their robustness and to reduce the leakage of secondary particle showers to downstream magnets. In this paper, we review possible failure scenarios and we quantify the energy deposition in superconducting coils by means of FLUKA shower calculations. Conceptual design studies for the new protection system are presented, with the main focus on the primary injection protection absorber (TDI) and the adjacent mask (TCDD).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY049

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTY052

New Method for Validation of Aperture Margins in the LHC Triplet

optics, kicker, dumping, collimation

2140

V. Chetvertkova, R. Schmidt, F.M. Velotti, D. Wollmann
CERN, Geneva, Switzerland
F.M. Velotti
EPFL, Lausanne, Switzerland

Funding: Work supported by COFUND grant PCOFUND-GA-2010-267194
Safety of LHC equipment including superconducting magnets depends not only on the proper functioning of the systems for machine protection, but also on the accurate adjustment of the protective devices such as collimators. In case of a failure of the extraction kicker magnets, which are part of the beam dumping system, it is important to ensure protection of the superconducting triplet magnets from missteered beam. The magnets are located to the right of Interaction Point 5 (IP5) and are protected by one set of collimators in the beam dumping insertion in IR6 and another set close to the triplet magnets. In this paper, a new method for verification of the correct collimator position with respect to the aperture is presented. It comprises the application of an extended orbit bump with identical trajectory as the beam trajectory after a deflection by the beam dump kickers. By further increasing the bump amplitude and successively moving in/out the collimators in the region of interest, the accurate positioning of the collimators can be validated. The effectiveness of the method for LHC IP5 and IP1 and both beams is discussed

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY052

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTY072

A New ILC Positron Source Target System Using Sliding Contact Cooling

target, positron, radiation, undulator

2196

W. Gai, D.S. Doran, R.A. Erck, G.R. Fenske, V.J. Guarino, W. Liu
ANL, Argonne, Illinois, USA

The R&D of the baseline positron source target for ILC is still ongoing after TDR due to the uncertainty of rotating vacuum seal and water cooling system of the fast spinning target wheel. Different institutes around the globe have proposed different approaches to tackle this issue. A spinning target wheel system with sliding contact cooling has been proposed by ANL. The proposed system eliminated the needs of rotating vacuum seal by using magnet bearings and vacuum compatible motor driven solid spinning wheel target. The energy deposited from positron production process is taken away via sliding cooling pads sliding against the spinning wheel. Details about this new target system are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY072

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTY079

Initial Modeling of Electron Cloud Buildup in the Final-focus Quadrupole Magnets of the SuperKEKB Positron Ring

electron, photon, quadrupole, positron

2218

J.A. Crittenden
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: US National Science Foundation contracts PHY-0734867, PHY-1002467, and PHY-1068662, US Department of Energy contract DE-FC02-08ER41538 and the Japan/US Cooperation Program
We present modeling results for electron cloud buildup in the final-focus quadrupole magnet nearest the interaction point in the SuperKEKB positron storage ring. The calculations employ as input recently obtained estimates of synchrotron radiation absorption rates on the vacuum chamber wall including the effect of photon scattering. While the effect both adds to and subtracts from photoelectron production at the points in the ring where unscattered photons strike the wall, it also produces cloud in the other regions. Results for beam-pipe-averaged and beam-averaged cloud densities are presented, as are estimates for the contribution to the fractional vertical coherent tune shift. The effect of the strong magnetic fields is studied and the dependence on the vacuum chamber surface secondary yield characteristics is considered. Cloud buildup is modeled with a 2D particle-in-cell macroparticle tracking code validated using recent measurements of electron trapping in a quadrupole magnet at the Cornell Electron Storage Ring Test Accelerator.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY079

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTY080

Synchrotron Radiation Analysis of the SuperKEKB Positron Storage Ring

photon, positron, scattering, electron

2222

J.A. Crittenden, D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
T. Ishibashi, Y. Suetsugu
KEK, Ibaraki, Japan

Funding: US National Science Foundation contracts PHY-0734867, PHY-1002467, and PHY-1068662, US Department of Energy contract DE-FC02-08ER41538 and the Japan/US Cooperation Program.
We report on modeling results for synchrotron radiation absorption in the SuperKEKB positron storage ring vacuum chamber including the effects of photon scattering on the interior walls. A detailed model of the geometry of the inner vacuum chamber profile has been developed and used as input to a photon tracking code. Particular emphasis is placed on the photon absorption rates in the electron-positron interaction region.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY080

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEBD2

Survey of Commissioning of Recent Storage Ring Light Sources

survey, factory, synchrotron, lattice

2482

M. Borland
ANL, Argonne, Ilinois, USA
R. Bartolini, I.P.S. Martin
DLS, Oxfordshire, United Kingdom
L.O. Dallin
CLS, Saskatoon, Saskatchewan, Canada
P. Kuske, R. Müller
HZB, Berlin, Germany
L.S. Nadolski
SOLEIL, Gif-sur-Yvette, France
F. Pérez
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
J.A. Safranek
SLAC, Menlo Park, California, USA
S. Shin
PAL, Pohang, Kyungbuk, Republic of Korea
Z.T. Zhentang
SINAP, Shanghai, People's Republic of China

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source and other existing storage ring light sources are contemplating replacing an existing, operating storage ring with a multi-bend achromat lattice. One issue is that existing light sources have large user communities who are greatly inconvenienced by extended shutdowns. Hence, there will be a premium placed on rapid commissioning of the new lattice. To better understand the possibilities, we undertook a survey of recent commissioning experience at third-generation light sources. We present a summary of that survey here.

Slides WEBD2 [0.173 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEBD2

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEBD3

Recent Developments on Superconducting Undulators at ANKA

undulator, operation, storage-ring, permanent-magnet

2485

S. Casalbuoni, A. Cecilia, S. Gerstl, N. Glamann, A.W. Grau, T. Holubek, C.A.J. Meuter, D. Saez de Jauregui, R. Voutta
KIT, Eggenstein-Leopoldshafen, Germany
C. Boffo, T.A. Gerhard, M. Turenne, W. Walter
Babcock Noell GmbH, Wuerzburg, Germany

At the synchrotron ANKA (ANgstrom source KArlsruhe) we pursue a research and development program on superconducting undulators (SCUs). This technology is of interest to improve the spectral characteristics of the emitted photons in third and fourth generation light sources. We present here the results obtained within the ongoing collaboration with the industrial partner Babcock Noell GmbH (BNG) on NbTi conduction cooled planar devices. Investigations on the application of alternative superconductors as well as a summary of the achievements reached to precisely characterize the magnetic field properties of SCUs and to measure the beam heat load to a cold bore are also described.

Slides WEBD3 [2.581 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEBD3

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA016

CsKSb Photocathode R&D with High Quantum Efficiency and Long Lifetime

laser, cathode, electron, linac

2526

Y. Seimiya, R. Kaku, M. Kuriki, A. Yokota
HU/AdSM, Higashi-Hiroshima, Japan
T. Konomi
UVSOR, Okazaki, Japan
T. Miyajima, M. Yamamoto
KEK, Ibaraki, Japan

Advanced electron linear accelerator such as Energy Recovery Linac and Free Electron Laser needs high brightness electron source. Photocathode is suitable for the high brightness requirement because some of them has low emittance and high quantum efficiency. In the photocathode, CsKSb multi-alkali photocathode has excellent features: high quantum efficiency, long lifetime, and driven by visible light, for example green laser. Therefore, the multi-alkali photocathode is considered to be one of the best candidates for the high brightness electron source of the advanced electron accelerator. We report developments of our evaporation system and results of quantum efficiency and lifetime measurement in Hiroshima University. Multi-alkali surface analyzation has being measured by ultra-violet photoemission spectroscopy to study conditions between the multi-alkali performances and the surface condition in Institute Molecular Science. We also report the status of the progress abort the study.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA016

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA037

Beam-Driven Terahertz Source Based on Open Ended Waveguide with a Dielectric Layer: Rigorous Approach

radiation, interface

2578

S.N. Galyamin, A.A. Grigoreva, A.V. Tyukhtin, V.V. Vorobev
Saint-Petersburg State University, Saint-Petersburg, Russia

Funding: Grant of the President of Russian Federation (No. 6765.2015.2) and Russian Foundation for Basic Research (No. 15-32-20985, 15-02-03913).
Terahertz frequency radiation (0.1-10 THz) is a promising tool for a number of scientific and practical applications. One promising scheme to obtain powerful and efficient THz emission is usage of beam-driven dielectric loaded structures [1]. Recently we have considered the problem where the microbunched ultrarelativistic charge exits the open end of a cylindrical waveguide with a dielectric layer and produces THz waves in a form of Cherenkov radiation [2]. To investigate the applicability of utilized approximations, we analyze here the case of orthogonal end of a waveguide with continuous filling. However, presented rigorous approach can be generalized for waveguide with vacuum channel. We use the combination of Wiener-Hopf technique and tailoring technique. The infinite linear system for magnitudes of reflected waveguide modes is obtained and solved numerically. We present typical field distributions over the aperture and typical radiation patterns in the Fraunhofer zone.
* S. Antipov et al., Appl. Phys. Lett. 100, 132910 (2012).
** S.N. Galyamin et al., Opt. Express. 22(8), 8902 (2014).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA037

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA038

Mode Transformation in Waveguide with Transversal Boundary Between Vacuum and Partially Dielectric Area

wakefield, radiation, acceleration, electron

2581

A.A. Grigoreva, T.Yu. Alekhina, S.N. Galyamin, A.V. Tyukhtin
Saint-Petersburg State University, Saint-Petersburg, Russia

We consider the mode transformation in a circular waveguide with a transversal boundary between a vacuum part and a part with a cylindrical dielectric layer and a vacuum channel. It is assumed that an incident mode can be both propagating and evanescent. Analysis is carried out with the using the mode decomposition technique. Numerical algorithm for calculating the mode transformation at an arbitrary channel radius is also developed. Typical dependences for the reflection and transmission coefficients on the channel radius are presented and discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA038

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA051

Investigations into Dielectric Laser-Driven Accelerators using the CST and VSIM Simulation Codes

acceleration, electron, laser, simulation

2618

Y. Wei, C.P. Welsch, G.X. Xia
Cockcroft Institute, Warrington, Cheshire, United Kingdom
K. Hanahoe, K. Hanahoe, O. Mete, G.X. Xia
UMAN, Manchester, United Kingdom
J. Smith
Tech-X, Boulder, Colorado, USA
Y. Wei, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

Funding: European Union’s 7th Framework Programme for research, development and demonstration under grant agreement no 289191 and the STFC Cockcroft core grant No.ST/G008248/1.
Dielectric laser-driven accelerators (DLAs) based on gratings structures confine the laser-induced accelerating field in a narrow vacuum channel where the electrons travel and are being accelerated. Recent proof-of-principle experiments have successfully demonstrated acceleration of electrons with accelerating gradients of up to 250 MV/m in such novel structures. This contribution presents detailed numerical studies into the acceleration of relativistic and non-relativistic electrons in double gratings silica structures. The optimization of these structures with regards to maximum acceleration efficiency for different spatial harmonics is discussed. Simulations were carried out using the commercial CST and VSIM simulation codes and results from both codes are shown in comparison.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA051

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA052

RF Conditioning of the Photo-Cathode RF Gun at the Advanced Photon Source - NWA RF Measurements

gun, detector, cathode, linac

2621

T.L. Smith, N.P. DiMonte, A. Nassiri, Y.-E. Sun, A. Zholents
ANL, Argonne, Illinois, USA

Funding: Work supported by U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357
A new S-band photo-cathode (PC) gun was recently installed and RF conditioned at the Advanced Photon Source (APS) Injector Test-stand (ITS) at Argonne National Lab (ANL). The APS PC gun is a LCLS type gun fabricated at SLAC [1]. The PC gun was delivered to the APS in October 2013 and installed in the APS ITS in December 2013. At ANL, we developed a new method of fast detection and mitigation of the gun’s internal arcs during the RF conditioning process to protect the gun from arc damage and to RF condition more efficiently. Here, we report the results of RF measurements for the PC gun and an Auto-Restart method for high power RF conditioning.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA052

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA068

Simulation of Laser Pulse Driven Terahertz Generation in Inhomogeneous Plasmas

plasma, radiation, laser, simulation

2661

C.M. Miao, T.M. Antonsen
UMD, College Park, Maryland, USA
J. Palastro
Icarus Research, Inc., Bethesda, Maryland, USA

Intense, short laser pulses propagating through inhomogeneous plasma can ponderomotively drive THz radiation. Here we consider a transition radiation mechanism (TRM) for THz generation as a laser pulse crosses a plasma boundary. Full format PIC simulations and theoretical analysis are conducted demonstrating that TRM results in low frequency, broad band, coherent THz radiation. The effect of a density ramp is also considered and shown to enhance the radiated energy.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA068

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPJE021

Fabrication and Demonstration of a Silicon Buried Grating Accelerator

electron, laser, acceleration, simulation

2717

A.C. Ceballos, R.L. Byer, K.J. Leedle, E.A. Peralta, O. Solgaard, K. Soong
Stanford University, Stanford, California, USA
R.J. England, I.V. Makasyuk, K.P. Wootton, Z. Wu
SLAC, Menlo Park, California, USA
A. Hanuka
Technion, Haifa, Israel
A.D. Tafel
Friedrich-Alexander Universität Erlangen-Nuernberg, University Erlangen-Nuernberg LFTE, Erlangen, Germany

Funding: Work supported by the U.S. Department of Energy under Grants DE-AC02-76SF00515, DE-FG06-97ER41276.
Using optical electromagnetic fields in dielectric microstructures, we can realize higher-energy accelerator systems in a more compact, low-cost form than the current state-of-the-art. Dielectric, laser-driven accelerators (DLA) have recently been demonstrated using fused silica structures to achieve about an order-of-magnitude increase in accelerating gradient over conventional RF structures.* We leverage higher damage thresholds of silicon over metals and extensive micromachining capability to fabricate structures capable of electron acceleration. Our monolithic structure, the buried grating, consists of a grating formed on either side of a long channel via a deep reactive ion etch (DRIE).** The grating imposes a phase profile on an incoming laser pulse such that an electron experiences a net change in energy over the course of each optical cycle. This results in acceleration (or deceleration) as electrons travel down the channel. We have designed and fabricated such structures and begun testing at the SLAC National Accelerator Laboratory. We report on the progress toward demonstration of acceleration in these structures driven at 2um wavelength.
* E.A. Peralta et al., Nature 503 (2013)
** C.M. Chang and O. Solgaard, Appl. Phys. Lett. 104 (2014)

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE021

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPJE023

Cathode Performance during Two Beam Operation of the High Current High Polarization Electron Gun for eRHIC

cathode, gun, electron, operation

2720

O.H. Rahman
Stony Brook University, Stony Brook, USA
M.A. Ackeret, J.R. Pietz
Transfer Engineering and Manufacturing, Inc, Fremont, California, USA
I. Ben-Zvi, C. Degen, D.M. Gassner, R.F. Lambiase, A.I. Pikin, T. Rao, B. Sheehy, J. Skaritka, E. Wang
BNL, Upton, Long Island, New York, USA
E. Dobrin, R.C. Miller, K.A. Thompson, C. Yeckel
Stangenes Industries, Palo Alto, California, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Two electron beams from two activated bulk GaAs photocathodes were successfully combined during the recent beam test of the High Current High Polarization Electron gun for eRHIC. The beam test took place at Stangenes Industries in Palo Alto, CA, where the cathodes were placed in radially opposite locations inside the high voltage shroud. No significant cross talking between the cathodes were found for the pertinent vacuum and low average current operation, which is very promising towards combining multiple beams for higher average current. This paper describes the cathode preparation, transport and cathode performance in the gun for the combining test, including the QE and lifetimes of the photocathodes at various steps of the experiment.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE023

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA003

Vacuum System Design for the Sirius Storage Ring

radiation, storage-ring, dipole, synchrotron

2744

R.M. Seraphim, O.R. Bagnato, R.O. Ferraz, H.G. Filho, G.R. Gomes, M. Nardin, R.F. Oliveira, B.M. Ramos, A.R.D. Rodrigues, M.B. Silva, T.M. da Rocha
LNLS, Campinas, Brazil

Sirius is a 3 GeV 4th-generation light source under construction by the Brazilian Synchrotron Light Laboratory (LNLS). Sirius will have a low emittance storage ring, 0.28 nm-rad, based on 20 cells of a highly compact lattice – 5-bend achromat (5BA). This lattice concept leaves very little space for components and therefore requires narrow vacuum chambers with tight mechanical tolerances. Most of the storage ring vacuum chambers will be made of OFS copper and have a circular cross section with inner diameter of 24 mm and a wall thickness of 1 mm. The unused synchrotron radiation will be distributed along the water cooled walls of the chambers. Due to the small conductance of the chambers, the vacuum pumping will be based on distributed concept and then non-evaporable getter (NEG) coating will be extensively used, with more than 95% of the chambers being coated. In this paper, we present an overview of the storage ring vacuum system and the main vacuum chambers fabrication developments.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA003

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA007

Experimental Study of Multipactor Suppression in Dielectric Materials

multipactoring, electron, Windows, target

2753

M. El Khaldi, W. Kaabi
LAL, Orsay, France

A novel coaxial resonator to investigate two-surface multipactor discharges on metal and dielectric surfaces in the gap region under vacuum conditions (~10^-8 mbar) has been designed and tested. The resonator is ~ 100 mm in length with an outer diameter of ~ 60 mm (internal dimensions). A pulsed RF source delivers up to 30 W average power over a wide frequency range 650-900 MHz to the RF resonator. The incident and reflected RF signals are monitored by calibrated RF diodes. An electron probe provides temporal measurements of the multipacting electron current with respect to the RF pulses. In this paper we compare and contrast the results from the RF power tests of the alumina (97.6% Al2O3) and quartz samples without a coating, “the non-coated samples” and the Alumina and quartz samples with a thick TiN coating in order to evaluate a home made sputtered titanium nitride (TiN) thin layers as a Multipactor suppressor. The effectiveness of this method is presented and discussed in the paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA007

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA008

RF Design of a High Gradient S-Band Travelling Wave Accelerating Structure for Thomx Linac

accelerating-gradient, impedance, linac, simulation

2757

M. El Khaldi, L. Garolfi
LAL, Orsay, France

There is growing demand from the industrial and research communities for high gradient, compact RF accelerating structures. The Thomx high gradient structure (HGS) is travelling wave (TW), quasi constant gradient section and will operate at 2998.55 MHz (30°C in vacuum) in the 2π/3 mode. The optimization of the cell shape (Electromagnetic design) has been carried out with the codes HFSS and CST MWS, in order to improve the main RF characteristics of the cavity such as shunt impedance, accelerating gradient, group velocity, modified Poynting vector, surface fields, etc. Prototypes with a reduced number of cells have been designed. For an input power of about 20 MW, EM simulation results show that an average accelerating gradient of 28 MV/m is achieved which corresponds to a peak accelerating gradient of 35 MV/m, a peak surface gradient of 44 MV/m and peak modified Poynting vector S_cmax of 0.24 MW/mm².

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA008

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA023

Advanced Multipoles and Appropriated Measurement Tools for Field Characterization of SIS100 Magnets

multipole, dipole, superconducting-magnet, ion

2805

P. Schnizer, E.S. Fischer, A. Gottsmann, F. Kaether, A. Mierau, H.G. Weiss
GSI, Darmstadt, Germany
B. Schnizer
TUG/ITP, Graz, Austria

The heavy ion synchrotron SIS100 utilises fast ramped superconducting magnets. Describing and measuring these magnets requires advanced multipoles next to well adapted measurement techniques. We cover briefly the required theory adapted to the measurements, show which designs were available and which decisions had to be taken for measuring curved superconducting magnets. The series of SIS100 dipole magnets is going to be produced. These magnets will be measured at GSI. We present the foreseen field measurement procedure, outline the currently ongoing tests and give our calibration strategy.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA023

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA034

Bakeout Concept for the HESR at FAIR

dipole, ion, heavy-ion, controls

2832

H. Jagdfeld, N. Bongers, P. Chaumet, F.M. Esser, F. Jordan, F. Klehr, G. Langenberg, U. Pabst, L. Semke
FZJ, Jülich, Germany

Forschungszentrum Jülich has taken the leadership of a consortium being responsible for the design of the High-Energy Storage Ring (HESR) going to be part of the FAIR project at GSI. The HESR is designed for antiprotons but can be used for heavy ion experiments as well. Therefore the vacuum is expected to be 10^-11 mbar or better. To achieve this also in the curved sections where 44 bent dipole magnets with a length of around 4.5 m will be installed, NEG coated dipole chambers will be used to reach the needed pumping speed and capacity. For activation of the NEG-material a bakeout system must be installed. The bakeout concept including the layout of the control system and the systematization of the heater packages for all components of the vacuum system are presented. Also the special design of the heater jackets inside the dipole will be shown where the geometrical parameters are very critical and space is very limited. The results of the simulation of temperature distribution in the dipole iron are compared to temperature measurements carried out at a testbench with different layouts of the heater jackets. The final design of the dipole heater jackets will be illustrated.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA034

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA037

Manufacturing and First Test Results of Euclid SRF Conical Half-wave Resonator

cavity, niobium, SRF, cryogenics

2841

E.N. Zaplatin
FZJ, Jülich, Germany
C.H. Boulware, T.L. Grimm, A. Rogacki
Niowave, Inc., Lansing, Michigan, USA
A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA
V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Funding: This Work is supported by the DOE SBIR Program, contract # DE-SC0006302.
Euclid TechLabs has developed a superconducting conical half-wave resonator (162.5 MHz β=v/c=0.11) for the high-intensity proton accelerator complex proposed at Fermi National Accelerator Laboratory. The main objective of this project is to provide a resonator design with high mechanical stability based on an idea of the balancing cavity frequency shifts caused by external loads. A unique cavity side-tuning option has been successfully implemented. Niowave, Inc. proposed a complete cavity production procedure including preparation of technical drawings, processing steps and resonator high-gradient tests. During manufacturing a series of cavity and helium vessel modifications to simplify their manufacturing were proposed. Following standard buffered chemical polish surface treatment and high-pressure rinse, a vertical test was carried out at Niowave’s facilities. Here we present the status of the project and the first high-gradient results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA037

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA038

Compact In-vacuum Quadrupoles for a Beam Transport System at a Laser Wakefield Accelerator

quadrupole, operation, focusing, laser

2845

A. Bernhard, V. Afonso Rodríguez, A.-S. Müller, J. Senger, W. Werner, C. Widmann
KIT, Karlsruhe, Germany

Funding: This work is partially funded by the German Federal Ministry for Education and Research under contract no. 05K10VK2 and 05K10SJ2.
For the transport and matching of electrons generated by a Laser Wakefield Accelerator (LWFA) a beam transport system with strong focusing magnets and a compact design is required. For the realization of such a beam transport system at the LWFA in Jena, Germany, two small series of inexpensive, modular quadrupoles were designed and built. The quadrupoles are iron-dominated electromagnets in order to keep the transport system adaptable to different energies and target parameters. To achieve the required field strength it was necessary to choose a small magnetic aperture. Therefore the magnets were designed for in-vacuum use with water-cooled coils. In this contribution the design, the realization and first field measurements of these quadrupoles are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA038

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA047

MHI's Production Activities of Accelerator Components

network, status, coupling, LLRF

2873

N. Shigeoka, S. Miura
MHI, Hiroshima, Japan

Mitsubishi Heavy Industries (MHI) is manufacturing various types of accelerator components. Recent production activities, mainly in a field of a normal conducting RF, will be reported in this presentation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA047

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA049

Development of the Ceramic Chamber Integrated Pulsed Magnet Fitting for a Narrow Gap

power-supply, dipole, storage-ring, kicker

2879

C. Mitsuda, T. Honiden, N. Kumagai, S. Sasaki
JASRI/SPring-8, Hyogo-ken, Japan
T. Nakanishi
SES, Hyogo-pref., Japan
A. Sasagawa
KYOCERA Corporation, Higashiomi-city, Shiga, Japan

We are pushing forward the development of a pulsed magnet that has a combined structure of magnet coils with a ceramic vacuum chamber, aiming to realize a small gap. The structure we are developing is that single turn air-coils are implanted along the longitudinal axis in the cylindrical ceramic chamber wall with thickness of 5mm. The ceramic wall works for separating the vacuum from the atmosphere, as well as holding the coil structures mechanically and the electrical insulation of coils. By this structure, magnet pole edges can be set close to the inside diameter of the chamber. The small gap increases magnetic field strength, which is for shorter length, and, as a result, the small magnet size reduces the inductance, which is for shorter pulse. We achieved the continuous operation over 200 days, without any failure, of current-excitation with 20 kV, 7.7 kA pulse with 4-μsec width and repetition of 1 Hz, using the dipole type prototype with a bore radius of 30 mm and magnetic length of 0.3m in 2013, while maintaining the vacuum pressure less than 10^-6 Pa. In this conference, we will discuss about the availability and practical utility with the magnetic field output performance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA049

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA059

Degassing of Kicker Magnet by In-situ Bake-out Method

kicker, radiation, plasma, shielding

2911

J. Kamiya, Y. Hikichi, M. Kinsho, N. Ogiwara
JAEA/J-PARC, Tokai-mura, Japan

New method of in-situ degassing of the kicker magnet in the beam line has been developed. The heater and heat shielding panels are installed in the vacuum chamber in this method. The heater was designed considering the maintainability. The graphite was selected as the heater and the high melting point metals were used as the reflectors just near the heater. The thermal analysis and the temperature measurement with the designed heater was performed. The ideal temperature distribution for the kicker degassing was obtained. The outgassing of the graphite during rising the temperature was measured. The result showed that the outgassing was extremely suppressed by the first heating. This means the outgassing of the graphite heater was negligible as long as it is used in the beam line without exposure to the air.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA059

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMN009

Design and Thermal Analysis of ADS Beam Stop

target, linac, rfq, interface

2931

M.X. Li, J.L. Wang, L. Wu
IHEP, Beijing, People's Republic of China

ADS beam stop is an important device which required for the commissioning and accelerator tests of Accelerator Driven Sub-critical System (ADS), it is used to stop the beam which power is about 100kW and consume energy of the beam. This paper will present a triangular prism structure of the ADS beam stop, its mechanical design is described in detail, and there are numerous grooves and ribs in the cooling plates which is the core component of the beam stop. The thermal analysis is performed and its result proves that the triangular prism structure meet the design requirement. Key words：Beam stop, ADS, thermal analysis, triangular prism structure.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN009

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMN021

Design and Research of Secondary Electron Emission Test Equipment with Low Electron Energy

electron, gun, ion, accumulation

2970

Y.H. Xu, L. Fan, Y.Z. Hong, X.T. Pei, J. Wang, Y. Wang, W. Wei, B. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

In particle accelerators, the secondary electrons resulting from the interaction between particles and vacuum chamber have a great impact on beam quality. Especially for positron, proton and heavy ion accelerators, massive electrons lead to electron cloud, which affects the stability, energy, emittance and beam life adversely. We have studied the secondary electron emission (SEE) of metal used for accelerators. A secondary electron emission measurement system with low electron energy has been designed and used to measure the SEE yield of metal and non-evaporable getter materials. With the equipment, we have obtained the characteristic of the SEE yield of stainless steel and oxygen free copper (OFC).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN021

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMN022

Optimization Design of Ti Cathode in Ceramic Pipe Film Coating Based on the Simulation Result of CST

electron, cathode, simulation, target

2973

J. Wang, L. Fan, Y.Z. Hong, X.T. Pei, Y. Wang, W. Wei, Y.H. Xu, B. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

The injection chamber at Hefei Light Source II (HLS II) consists of four ceramic vacuum chambers whose inner surface were coated with TiN thin film. The cross section of ceramic pipes is special racetrack structure. In order to improve the uniformity of the film, the structure of the cathode Ti plate needed to be optimized. In this article, CST PARTICLE STUDIOTM software had been used to simulate the influence of different target structure on discharge electric field distribution and electrons trajectories. Furthermore, the reliability of the simulation were analysed compared with the experimental results. Also, we put forward the optimization design of Ti cathode structure which could satisfy the requirement of uniformity of the thin film.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN022

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMN023

Vacuum System of the Storage Ring of HLS-II

storage-ring, synchrotron, radiation, synchrotron-radiation

2976

Y. Wang, L. Fan, Y.Z. Hong, X.T. Pei, J. Wang, W. Wei, B. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

HLS storage-ring has been operated for more than twenty-five years. In 2014 we began to upgrade the machine, which is called HLS-II. The emittance is reduced to 40 nmrad, five insertion devices are added and the injection energy increases to 800MeV. Now the machine commissioning has already been completed. The typical life time is 300 mins at 300mA, 800MeV. The average pressure of static and dynamic vacuum are below 2×10^-8 Pa and 1.2×10-7 Pa respectively. The design, installation and commissioning of the vacuum system of the storage ring are detailedly stated in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN023

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMN028

Preliminary Mechanical Design of Ceramic Pipe Film Coating Equipment at Hefei Light Source II

cathode, injection, simulation, experiment

2988

J. Lu
NPU, Xi'an Shaanxi, People's Republic of China
L. Fan, Y.Z. Hong, X.T. Pei, J. Wang, Y. Wang, W. Wei, Y.H. Xu, B. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Ceramic vacuum chambers are important components of the injection chamber at Hefei Light Source II (HLS II). The length of each Ceramic vacuum chamber is 350 mm and their inner surface is coated with TiN thin film whose properties are low secondary electron yield (SEY), good electrical conductivity, stability of performance, ability to block hydrogen permeation. Considering that the cross section of Ceramic pipe is racetrack structure, Ti plate was chose as the cathode to improve TiN thin film deposition rate. Meanwhile, the authors designed a motor drive magnetron sputtering film coating equipment to obtain uniform TiN film.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN028

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMN034

Electron Emission from Surface Roughness on Cavity in Low Temperature

electron, radiation, cavity, gun

3003

H. Kim, H.J. Cha, S. Choi, W.K. Kim, G.-T. Park
IBS, Daejeon, Republic of Korea
Y. Chang
Hanshin University, Kyungki, Republic of Korea

Electron emission phenomenon from surface roughness on cavity is investigated. The distribution of the electric field from the surface roughness can be obtained on cavity surface. The field emission is calculated from the electric field distribution. The generalized electron emission from electric field and temperature effect is also calculated on the surface roughness of the cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN034

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMN035

QWR and HWR Cryomodules for Heavy Ion Accelerator RAON

cryomodule, cavity, alignment, radiation

3006

W.K. Kim, H.J. Cha, H. Kim, H.J. Kim, Y. Kim, M. Lee, G.-T. Park
IBS, Daejeon, Republic of Korea

The accelerator called RAON has five kinds of cryomodules such as QWR, HWR1, HWR2, SSR1 and SSR2. The QWR and HWR1 cryomodules are designed and fabricated. The cryomodules will be operated at 2 K and 4 K in order to operate the superconducting cavities. The static heat load of the system was analytically computed for each configuration. The functional requirement of the cryomodules and the static heat load measurement of the QWR and HWR1 cryomodules are presented in this research.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN035

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMN039

RF Accelerating Voltage of PLS-II Superconducting RF System for Stable Top-up Operation with Beam Current of 400 mA

operation, cavity, LLRF, injection

3015

Y.D. Joo, M.-H. Chun, T. Ha, I. Hwang, B.-J. Lee, I.S. Park, S. Shin, Y.U. Sohn, I.H. Yu
PAL, Pohang, Kyungbuk, Republic of Korea

During the beam store test up to 400 mA in the storage ring, it was observed that the vacuum pressure around the RF window of the superconducting cavity rapidly increases over the interlock level limiting the availability of the maximum beam current storing. We investigated the cause of the window vacuum pressure increment by studying the changes in the electric field distribution at the superconducting cavity and waveguide according to the beam current. An equivalent physical modeling was developed using a finite-difference time-domain (FDTD) simulation and it revealed that the electric field amplitude at the RF window is exponentially increased as the beam current increases, thus this high electric field amplitude causes a RF breakdown at the RF window.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN039

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMN041

Technical Overview of Bunch Compressor System for PAL XFEL

dipole, quadrupole, diagnostics, electron

3018

H.-G. Lee, Y.-G. Jung, H.-S. Kang, D.E. Kim, K.W. Kim, S.B. Lee, D.H. Na, B.G. Oh, K.-H. Park, H.S. Suh, Y.J. Suh
PAL, Pohang, Kyungbuk, Republic of Korea

Pohang Accelerator Laboratory (PAL) is developing a SASE X-ray Free Electron Laser based on 10 GeV linear accelerator. Bunch compressor (BC) systems are developed to be used for the linear accelerator tunnel. It consists of three hard X-ray line and one soft X-ray line. BC systems are composed of four dipole magnets, three quadrupole magnet, BPM and collimator. The support system is based on an asymmetric four-dipole magnet chicane in which asymmetry can be optimized. This flexibility is achieved by allowing the middle two dipole magnets to move transversely. In this paper, we describe the design of the stages used for precise movement of the bunch compressor magnets and associated diagnostics components.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN041

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMN042

400 mA Beam Store with Superconducting RF Cavities at PLS-II

cavity, SRF, operation, cryomodule

3021

Y.U. Sohn, M.-H. Chun, T. Ha, M.S. Hong, Y.D. Joo, H.-S. Kang, H.-G. Kim, K.R. Kim, T.-Y. Lee, C.D. Park, H.J. Park, I.S. Park, S. Shin, I.H. Yu, J.C. Yun
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: Minister of Science, ICT and Future Planning
Three superconducting RF cavities were commissioned with electron beam in way of one by one during the last 3 years, and now PLS-II is in user service on the way of beam current to 400mA, the target of PLS-II. The cavities and cryomodules were prepared with SRF standard technology and procedures, then vertical test, windows conditioning, cryogenic test in each cryomodule, horizontal power test, conditioning, and commissioning without and with beam at PLS-II tunnel by collaboration with industries. All the cavities showed stable performances as good as not-observing any RF instability from cavities, couplers and windows up to 400 mA beam store, but observing several cavity quenches and minor vacuum bursts by abrupt power with control and human errors. The initial beam current for user run were recorded as 150 mA with one cavity, 280 mA with two cavities and 320 mA with three cavities. The 400 mA beam was also achieved with two cavities by decay mode and also with three cavities by top-up mode. The stabilities of RF amplitude and phase are good enough not to induce beam instabilities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN042

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMN051

Design of a Superconducting Gantry Cryostat

quadrupole, dipole, proton, cryogenics

3043

C. Bonțoiu, I. Martel, J. Sanchez-Segovia
University of Huelva, Huelva, Spain
R. Berjillos, J.P.B. Perez
TTI, Santander, Spain

The University of Huelva in collaboration with the Andalusian Foundation for Health Research (FABIS) and the TTI Company is currently involved in developing and assembling a prototype for a compact superconducting proton gantry with the goal to generate a business case within the narrow niche of hadron therapy. This article presents the current status of the engineering design for the cryostat and beam steering system. An account for the mechanical deformations due to magnetic forces and weight is also presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN051

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMN056

High Power Testing of the First Re-buncher Cavity for LIPAC

cavity, electron, radiation, low-level-rf

3051

F. Toral, D. Gavela, I. Podadera, D. Regidor, M. Weber, C. de la Morena
CIEMAT, Madrid, Spain
B. Bravo, R. Fos, J.R. Ocampo, F. Pérez, A. Salom, P. Solans
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

Funding: This work is partially supported by the Spanish Ministry of Economy and Competitiveness under projects AIC-A-2011-0654 and the Agreement as published in BOE, 16/01/2013, page 1988
Two re-buncher cavities will be installed at the Medium Energy Beam Transport (MEBT) of the LIPAc accelerator, presently being built at Rokkasho (Japan). They are IH-type cavities with 5 gaps and will provide an effective voltage of 350 kV at 175 MHz for deuterons at 5 MeV. The first prototype has been designed at CIEMAT and built by the Spanish industry. The high power tests and RF conditioning have been successfully performed at the ALBA/CELLS RF laboratory. A solid state power amplifier, which has been developed by CIEMAT and its partner companies at Spain for the LIPAc RF System, has been used for the tests. The cavity has shown a performance according to calculations, regarding the dissipated power, peak temperatures and coupling factor. RF conditioning was started with a duty cycle of 3%, which was increased gradually till continuous wave (CW), which is the nominal working mode in LIPAc.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN056

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMN061

ESS PLC Controls Strategy

PLC, timing, controls, hardware

3066

D.P. Piso, P. Arnold, S.L. Birch, T. Gahl, T. Korhonen, A. Nordt, J.G. Weisend
ESS, Lund, Sweden

The European Spallation Source ESS AB is an accelerator-driven neutron spallation source. The Integrated Controls System (ICS) division is responsible for providing controls and monitoring for all parts of the machine (accelerator, target, neutron scattering systems and conventional facilities). Also, Accelerator Division, Target Division and other parts of the organisation will be deploying PLC Automation Systems. A large number of applications have been identified across all the facility where PLCs will be used: cryogenics, vacuum, water-cooling, fluid systems, power systems, and safety \& protection systems. This work describes the different activities put in place and proposes the strategy followed at ESS regarding PLC technologies. This strategy consists not only of the standardisation of a PLC vendor but also testing activities, generation of documentation and standardization of other aspects (for instance, regarding installation). The documentation about PLC controls integration and standardisation and the approach to insert PLCs in the different controls workflows are described. Finally, the results of different tests (PLC timing correlation) are shown.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN061

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMN067

Upgrade of the TCDQ Diluters for the LHC Beam Dump System

controls, PLC, survey, extraction

3079

M.G. Atanasov, W. Bartmann, J. Borburgh, C. Boucly, C. Bracco, L. Gentini, B. Moles, W.J.M. Weterings
CERN, Geneva, Switzerland

The TCDQ diluters are installed as part of the LHC beam dump system to protect the Q4 quadrupole and other downstream elements during a beam dump that is not synchronised with the abort gap, or in case of erratic firing of the extraction kickers. These diluter elements installed during Run 1 were compatible with beam up to 60 % of the nominal intensity, which was insufficient for the second run of the LHC. This paper describes the requirements for the upgrade done during the First Long Shutdown (LS1), to make the TCDQ compatible with the full 7 TeV LHC beam at intensities required for the future runs of the machine. Subsequently the mechanical design changes, implementation and commissioning of the TCDQ are reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN067

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMN068

Upgrade of the CERN SPS Extraction Protection Elements TPS

extraction, septum, kicker, proton

3083

J. Borburgh, B. Balhan, M.J. Barnes, C. Baud, M.A. Fraser, V. Kain, F.L. Maciariello, G.E. Steele, F.M. Velotti
CERN, Geneva, Switzerland

In 2006 the protection devices upstream of the septa in both extraction channels of the CERN SPS to the LHC were installed. Since then, new beam parameters have been proposed for the SPS beam towards the LHC in the framework of the LIU project. The mechanical parameters and assumptions on which these protection devices presently have been based, need validation before the new upgraded versions can be designed and constructed. The paper describes the design assumptions for the present protection device and the testing program for the TPSG4 at HiRadMat to validate them. Finally the requirements and the options to upgrade both extraction protection elements in the SPS are described.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN068

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA003

Measurement of NEG Coating Performance Variation in the LHC after the First Long Shutdown

simulation, collider, injection, hadron

3100

V. Bencini, V. Baglin, G. Bregliozzi, P. Chiggiato, R. Kersevan, C. Yin Vallgren
CERN, Geneva, Switzerland

During the Long Shutdown 1 (LS1) of the Large Hadron Collider, 90% of the Non-Evaporable Getter (NEG) coated beam pipes in the Long Straight Sections (LSS) were vented to undertake the planned upgrade and consolidation programmes. After each intervention, an additional bake-out and NEG activation were performed to reach the vacuum requirements. An analysis of the coating performance variation after the additional activation cycle has been carried out by using ultimate pressure and pressure build-up measurements. In addition, laboratory measurements have been carried out to mimic the LHC coated beam pipe behaviour. The experimental data have been compared with calculation obtained by Molflow+.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA003

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA004

Present Quality Assurance for the LHC Beam Vacuum System and its Future Improvement

controls, operation, cryogenics, status

3103

J. Sestak, V. Baglin, G. Bregliozzi, P. Chiggiato
CERN, Geneva, Switzerland

During the Long Shutdown 1 (LS1), the LHC beam vacuum system was upgraded to minimize dynamic vacuum effects like stimulated desorption and beam-induced electron multipacting. A quality assurance plan was mandatory due to the demanding vacuum performance and the limited access to the equipment during the following operation period. Laboratory assessment tests and underground interventions were performed following well-defined and approved procedures. All vacuum related activities were documented and written reports stored in dedicated databases. Quality controls were performed to find mechanical, cabling and equipment functionality non-conformities. Possible issues were identified, classified and tracked in a non-conformity database for future corrective actions. This contribution give an overview of the quality assurance policy followed during the LS1 and the non-conformities reported after quality control. Possible future improvements are also discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA004

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA005

Characterization of the RF Fingers Contact Force for the LHC Warm Vacuum Bellow Modules

impedance, alignment, operation

3106

C. Blanch Gutiérrez, V. Baglin, G. Bregliozzi, P. Chiggiato, R. Kersevan
CERN, Geneva, Switzerland

Along the 27 Km of LHC beam pipe, various types of vacuum bellow modules are needed to compensate the mechanical misalignments of the vacuum chambers during installation and to absorb their thermal expansion during the bake-out. In order to reduce the beam impedance during operation with beams these modules are equipped with RF bridges to carry the image current. They are usually made out of a copper tube insert at one side and Cu-Be RF fingers at the other end of the module. A spring is used to keep the contact between the RF fingers and the tube insert. The geometry and the choice of this spring become critical to ensure a good electrical contact. In this paper, a description of the test bench used to measure the contact force together with the procedure applied and the measurements performed are given. A summary of the maximum radial and axial offsets between the RF fingers and the insert tube while keeping a good electrical contact is presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA005

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA006

Recommissioning of the COLDEX Experiment at CERN

electron, cryogenics, controls, experiment

3109

R. Salemme, V. Baglin, F. Bellorini, G. Bregliozzi, K. Brodzinski, P. Chiggiato, P. Costa Pinto, P. Gomes, A. Gutierrez, V. Inglese, B. Jenninger, R. Kersevan, E. Michel, M. Pezzetti, B. Rio, A. Sapountzis
CERN, Geneva, Switzerland

COLDEX (Cold bore Experiment), installed in the Super Proton Synchrotron (SPS) at CERN, is a test vacuum sector used in 2001-2004 to validate the Large Hadron Collider (LHC) cryogenic vacuum system with LHC type proton beams. Its cryostat houses a 2.2 m long copper perforated beam screen surrounded by a stainless steel cold bore, both individually temperature controlled down to 5 and 3 K, respectively. In the framework of the development for the High Luminosity upgrade of the LHC (HL-LHC), COLDEX has been re-commissioned in 2014. The objective of this re-commissioning is the validation of the performance of amorphous carbon coatings at cryogenic temperature with LHC type beams. The existing COLDEX beam screen has been dismounted and carbon coated, while a complete overhaul of the vacuum, cryogenic and control systems has been carried out. This contribution describes the phases of re-commissioning and reviews the current experimental set-up. An overview of the possible measurements with COLDEX, in view of its HL-LHC experimental program, is also presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA006

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA007

Amorphous Carbon Coatings at Cryogenic Temperatures with LHC Type Beams: First Results with the COLDEX Experiment

electron, cryogenics, simulation, experiment

3112

R. Salemme, V. Baglin, G. Bregliozzi, P. Chiggiato, R. Kersevan
CERN, Geneva, Switzerland

Extrapolations of electron cloud data from the Large Hadron Collider (LHC) Run 1 to the High Luminosity upgrade (HL-LHC) beam parameters predict an intolerable increase of heat load on the beam screens of the inner triplets. Amorphous carbon (a-C) coating of the beam screen surface is proposed to reduce electron cloud production, thereby minimising its dissipated power. To validate this solution, the COLDEX experiment has been re-commissioned. Such equipment mimics the performance of the LHC cold bore and beam screen cryogenic vacuum system in presence of LHC beams in the Super Proton Synchrotron (SPS). The main objective of the study is the performance evaluation of a-C coatings while operating the beam screen in the 10 to 60 K temperature range and cold bore below 3 K. This paper reviews the status of COLDEX and the results obtained during its first experimental runs.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA007

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA009

Propagation of Radioactive Contaminants Along the Isolde Beamline

target, ion, simulation, proton

3115

R. Kersevan, M. Ady, A. Dorsival, A. Gottberg, M. Maietta, G. Vandoni
CERN, Geneva, Switzerland

The vacuum system of RIB facilities is entirely hermetical, with storage of effluents and controlled release to atmosphere after a decay time. In Isolde, distributed primary pumping is sectorized in three parts, but all effluents are conveyed together in a unique tank. Thus, highly contaminated gas from the target and front end may be mixed with less contaminated gas from the beam transfer lines. This study aims at analysing and quantifying the distribution and propagation of neutral rare gas radioactive isotopes along the Isolde beam-line by numerical simulation (steady-state and time resolved Test-Particle Monte-Carlo, Molflow+) and experimental means. The time-resolved Monte-Carlo integrates decay time for the propagating species. To measure the distribution of contaminants, sampling filters are installed at the exhaust of the vacuum turbo-molecular pumps. Comparison between simulation and experiment shows excellent agreement, confirming the pertinence of the Monte-Carlo tool to radioactive species propagation. The filtering effect of magnetic sectors, the RFQ Cooler, and Buncher on the propagating neutral isotopes are quantified.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA009

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA010

The Vacuum System of the Extra-Low Energy Antiproton Decelerator ELENA at CERN

antiproton, dipole, ion, electron

3119

R. Kersevan
CERN, Geneva, Switzerland

The Extra-Low ENergy Antiproton decelerator (ELENA) project is under way since 2011. In the past 3 years, it has considerably evolved into a detailed design for the ring and the transfer lines. It is a small machine, ~30 m in circumference, with a rather tight specification for the average pressure seen by the anti-proton beams injected by the anti-proton decelerator (AD). The average pressure in ELENA must be limited to 4x10^-12 mbar (H2-equivalent) in order to limit the charge-exchange losses during the rather long deceleration process (several tens of seconds), during which the energy of the beam is reduced and the electron-cooler is used twice in order to decrease the transverse emittance of the anti-proton beam. This paper will discuss the design of the chambers of the injection line, extraction line and the ring. It will also mention the actual status of the vacuum system for the transfer lines to the experiments, LNE, which are under finalisation. The results of detailed 3D simulations made with the test-particle montecarlo code Molflow+ will be discussed, alongside with the choice for the pumping system, mainly distributed NEG-coatings and integrated NEG/ion-pumps.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA010

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA011

Photodesorption and Electron Yield Measurements of Thin Film Coatings for Future Accelerators

electron, photon, experiment, solenoid

3123

R. Kersevan, M. Ady, P. Chiggiato
CERN, Geneva, Switzerland
T. Honda, Y. Tanimoto
KEK, Tsukuba, Japan

The performance of future accelerators could be limited by electron cloud phenomena and high photodesorption yields. For such a reason, the study of secondary electron and photodesorption yields of vacuum materials is essential. The eradication or mitigation of both secondary electron and molecule desorption could strongly reduce the beam scrubbing time and increase the availability of nominal beams for experiments. Surface modifications with the desired characteristics can be achieved by thin-film coatings, in particular made of amorphous carbon and non-evaporable getters (NEG). In the framework of a new collaboration, several vacuum chambers have been produced, and different coatings on each of them have been applied. The samples were then irradiated at KEK’s Photon Factory with SR light of 4 keV critical energy during several days, allowing the measurement of the photodesorption yield as a function of the photon dose. This paper presents the experiment and briefly summarizes the preliminary photodesorption and photoelectron yield data of different coatings. The results can be used for future machine design with similar conditions, such as the FCC-hh.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA011

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA012

Synchrotron Radiation Distribution and Related Outgassing and Pressure Profiles for the HL-LHC Final Focus Magnets

photon, radiation, synchrotron, synchrotron-radiation

3127

R. Kersevan
CERN, Geneva, Switzerland

The HL-LHC final focus area, from D2 to the interaction point, has been modelled based on the latest vacuum chamber geometry and orbits. The synchrotron radiation (SR) fans are computed using the Monte Carlo code SYNRAD⁺, in the dipole approximation regime. The angular and energy dependence of the reflectivity of the copper surfaces is considered, as well as the surface roughness. Once the SR distributions are computed, they are converted into outstanding profiles by using data available in literature. The test-particle Monte Carlo code Molflow+ is then used and the related pressure profiles and gas density distribution are computed. This allows an optimization of the pattern of the perforations on the tungsten-shielded beam screen proposed for this area. It is shown that the resultant gas density is below the limit dictated by the ATLAS and CMS detectors.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA013

The Assembly Experience of the First Cryo-module for HIE-ISOLDE at CERN

cavity, solenoid, instrumentation, linac

3131

Y. Leclercq, G. Barlow, J.A. Bousquet, A. Chrul, P. Demarest, J-B. Deschamps, J.A. Ferreira Somoza, J. Gayde, M. Gourragne, A. Harrison, G. Kautzmann, D. Mergelkuhl, V. Parma, M. Struik, M. Therasse, L.R. Williams
CERN, Geneva, Switzerland
J. Dequaire
Intitek, Lyon, France

The HIE ISOLDE project aims at increasing the energy of the radioactive ion beams of the existing REX ISOLDE facility from the present 3 MeV/u up to 10 MeV/u for A/q to 4.5. The upgrade includes the installation of a superconducting linac in successive phases, for a final layout containing two low-β and four high-β cryo-modules. The first phase involves the installation of two high-B cryo-modules, each housing five high- β superconducting cavities and one superconducting solenoid, aligned within tight tolerances. After having designed and procured the cryo-module components, the first units is now being assembled at CERN, in a dedicated facility including class100 (ISO5) clean rooms equipped with specific tooling. The assembly is foreseen to be ultimate and the cryo-module cold tested by May 2015. In this paper, after a brief description of the main design features of the cryo-module , we present the assembly of the first unit, including the methodology, special tools, assembly procedures and quality assurance aspects. We report on the experience from this first assembly, including tests results, and present prospects for the next-coming cryo-module assemblies.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA013

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA019

Development and Production of Non-evaporable Getter Coatings for MAX IV

photon, cathode, electron, cavity

3145

P. Costa Pinto, B. Bártová, B. Holliger, S. Marques Dos Santos, V. Nistor, A. Sapountzis, M. Taborelli, I. Wevers
CERN, Geneva, Switzerland
J. Ahlbäck, E. Al-Dmour, M.J. Grabski, C. Pasquino
MAX-lab, Lund, Sweden

MAX IV is presently under construction at Lund, Sweden, and the first beam for the production of synchrotron radiation is expected to circulate in 2016. The whole set of 3-GeV ring beam pipes is coated with Ti-Zr-V Non Evaporable Getter (NEG) thin film in order to fulfil the average pressure requirement of 1x10^-9 mbar, despite the compact magnet layout and the large aspect ratio of the vacuum chambers. In this work, we present the optimisations of the coating process performed at CERN to coat different geometries and mechanical assembling used for the MAX IV vacuum chambers; the morphology of the thin films is analysed by Scanning Electron Microscopy; the composition and thickness is measured by Energy Dispersive X-ray analysis; the activation of the NEG thin film is monitored by X-ray Photoemission Spectroscopy; the vacuum performance of the coated beam pipes is evaluated by the measurement of hydrogen sticking coefficient. The results of the coating production characterisation for the 84 units coated at CERN are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA020

Titanium Coating of Ceramics for Accelerator Applications

cathode, Windows, electron, target

3148

W. Vollenberg, P. Costa Pinto, B. Holliger, A. Sapountzis, M. Taborelli
CERN, Geneva, Switzerland

Titanium thin films can be deposited on ceramics, in particular alumina, without adherence problems. Even after air exposure their secondary electron yield is low compared to alumina and can be further reduced by conditioning or beam scrubbing. In addition, depending on the film thickness, titanium provides different surface resistances that fulfil requirements of ceramics in particle accelerators. Titanium thin films (MOhm square range) are used to suppress electron multipacting and evacuate charges from ceramic surfaces. Thicker films (5-25 Ω square range) are applied to lower the surface resistance so that the beam impedance is reduced. In this contribution, we present the results of a development aimed at coating 2-meter long alumina vacuum chambers with a uniform surface resistivity by a dedicated DC magnetron sputtering configuration.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA020

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA021

Status of HIE-ISOLDE SC Linac Upgrade

cavity, cryomodule, linac, niobium

3151

A. Sublet, L. Alberty, K. Artoos, S. Calatroni, O. Capatina, M.A. Fraser, N.M. Jecklin, Y. Kadi, P. Maesen, G.J. Rosaz, K.M. Schirm, M. Taborelli, M. Therasse, W. Venturini Delsolaro, P. Zhang
CERN, Geneva, Switzerland

The HIE-ISOLDE upgrade project at CERN aims at increasing the energy of radioactive beams from 3MeV/u up to 10 MeV/u with mass-to-charge ratio in the range 2.5-4.5. The objective is obtained by replacing part of the existing normal conducting linac with superconducting Nb/Cu cavities. The new accelerator requires the production of 32 superconducting cavities in three phases: 10 high-beta cavities for phase 1 (2016), 10 high-beta cavities for phase 2 (2017) and possibly 12 low-beta cavities for phase 3 (2020). Half of the phase 1 production is completed with 5 quarter-wave superconducting cavities ready to be installed in the first cryomodule. The status of the cavity production and the RF performance are presented. The optimal linac working configuration to minimize cryogenic load and maximize accelerating gradient is discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA021

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA032

Study on the LN2 Consumption of the Beamline Ln2 Transfer System for TPS Project*

controls, cryogenics, operation, superconducting-RF

3182

H.C. Li, W.S. Chan, S.-H. Chang, W.-S. Chiou, F. Z. Hsiao, W.R. Liao, T.F. Lin, H.H. Tsai
NSRRC, Hsinchu, Taiwan

One system to transfer liquid nitrogen (LN2) will be installed at TPS in 2015 for beamline. This system includes two transfer lines (length 600 m), eight keep-full devices and 26 branch lines with 26 control valves for 24 straight sections of beam lines. The required consumption of LN2 for each beam line is 30 L/h. An archive system was developed to monitor and to calculate the consumption of LN2 for each beam line. This consumption was calculated based on the pressure difference and the flow coefficient (Kv) of the control valve. This paper presents the configuration of the LN2 supply system at NSRRC and a test bench of the calculation of LN2 consumption. A simple test result is presented and discussed.
Cryogenics

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA032

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA046

Outgassing Analysis During Transport for 14m Long Arc-Cell Vacuum Chambers of the Taiwan Photon Source

ion, photon, storage-ring, electron

3219

L.H. Wu, C.K. Chan, C.H. Chang, C.-C. Chang, S.W. Chang, Y.P. Chang, B.Y. Chen, J.-R. Chen, Z.W. Chen, C.M. Cheng, G.-Y. Hsiung, S-N. Hsu, H.P. Hsueh, C.S. Huang, Y.T. Huang, T.Y. Lee, I.C. Yang
NSRRC, Hsinchu, Taiwan
J.-R. Chen
National Tsing Hua University, Hsinchu, Taiwan

An outgassing analysis during transportation for the large, 14-m-long, ultra-high-vacuum aluminum arc-cell chambers of the Taiwan Photon Source (TPS) was performed using residual gas analysis (RGA). Each cell was baked to 150 °C in the laboratory to achieve ultra-high vacuum. Under pumping by primarily ion pumps (IP) and non-evaporable getter (NEG) pumps, the cells obtained pressures of 6.4×10^-9 Pa on average, and the main residual gas was H2. Here, vacuum pressure measurements and residual gas analyses were performed in situ while a cell chamber was being transported. It was found that the vibration of the arc-cell vacuum chamber caused the pressure to rise abruptly; in this case, the main outgassing gas was CH4. Once the arc cell had been fully installed, the vacuum pressure gradually decreased to the original vacuum pressure because of the pumping effect of the ion gauges.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA046

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA048

Behavior of Vacuum Pressure in TPS Vacuum System

storage-ring, booster, synchrotron, photon

3222

I.C. Yang, C.K. Chan, C.-C. Chang, B.Y. Chen, J.-R. Chen, C.M. Cheng, J. -Y. Chuang, G.-Y. Hsiung, C.K. Kuan, C.C. Liang, I.C. Sheng, L.H. Wu
NSRRC, Hsinchu, Taiwan

Taiwan Photon source (TPS) is in its first stage commissioning in 2014-2015. The vacuum systems of TPS were installed for commissioning since August 2014. After four months performance testing and subsystem integration, the commissioning of booster ring began on 12 December and then the first 3 GeV beam was stored on 31 December. 100mA beam current, 35Ah accumulated beam dose was archived in March 2015 before machine shut down. The average pressure in storage ring is 2.8×10^-8 Pa before commissioning, rising to 1.33×10-7 Pa with 100mA beam current. In 35Ah accumulated beam dose, the target of beam cleaning effect has reached to 8.92×10-10 Pa/mA. The vacuum performance, experience and events during commissioning will be presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA048

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA049

Demagnetize Booster Chamber in TPS

booster, dipole, synchrotron, operation

3225

I.C. Sheng, C.-T. Chen, C.K. Kuan, I.C. Yang
NSRRC, Hsinchu, Taiwan

Taiwan Photon Source (TPS) project starts its booster commissioning starts from August 2014. Few issues have been discovered and fixed. Since the booster aperture is relatively small and number of magnets is barely sufficient. Therefore extreme precise control of booster chamber alignment and the corresponding chamber permeability is as well important. In this paper, we present how the booster chamber is uninstalled, demagnetized and reinstalled within three weeks. This procedure is proven to result in the lowest booster chamber permeability in the world and a good high vacuum booster ring is built in 3 weeks.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA049

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA052

Test Cavity and Cryostat for SRF Thin Film Evaluation

cavity, niobium, SRF, cryogenics

3232

O.B. Malyshev, P. Goudket, L. Gurran, D.O. Malyshev, S.M. Pattalwar, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt, L. Gurran
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
P. Goudket, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom
T.J. Jones, E.S. Jordan
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

In developing superconducting coatings for SRF cavities, the coated samples are tested using various techniques such as resistance measurements, AC and DC magnetometry which provide information about the superconducting properties of the films such as RRR, Hc1, Hc2 and vortex dynamics. However, these results do not allow the prediction of the superconducting properties at RF frequencies. A dedicated RF cavity was designed to evaluate surface resistive losses on a flat sample. The cavity contains two parts: a half-elliptical cell made of bulk Nb and a flat Nb disc. The two parts can be thermally and electrically isolated via a vacuum gap, whereas the electromagnetic fields are constrained through the use of RF chokes. Both parts are conduction cooled hence the system is cryogen free. The flat disk can be replaced with a sample, such as a Cu disc coated with Nb film. The RF test provide the cavity Q-factor and thermometrical measurements of the losses on the sample. The design advantages are that the sample disc can be easily installed and replaced; installing a new sample requires no brazing/welding/vacuum or RF seal, so the sample preparation is simple and inexpensive.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA052

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA054

Commissioning of the Transverse Deflecting Cavity on VELA at Daresbury Laboratory

cavity, electron, klystron, coupling

3239

A.E. Wheelhouse, R.K. Buckley, S.R. Buckley, L.S. Cowie, P. Goudket, L. Ma, J.W. McKenzie, A.J. Moss
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt, M. Jenkins
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

A 9-cell S-band transverse deflecting copper cavity (TDC) has been designed and built to provide a 5 MV transverse kick in order to perform longitudinal profile measurements of the electron bunch on the Versatile Electron Linear Accelerator (VELA) at Daresbury Laboratory. The cavity has been manufactured by industry and has been field flatness tuned using a beadpull system. The cavity has then been installed on to the VELA facility and commissioned for operation with the electron beam. This paper discusses the tuning and the RF conditioning of the cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA054

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPTY012

Multiple Scattering Effects of a Thin Beryllium Window on a Short, 2 nC, 60 MeV Bunched Electron Beam

scattering, simulation, experiment, emittance

3280

E.E. Wisniewski, M.E. Conde, W. Gai, G. Ha, J.G. Power
ANL, Argonne, Illinois, USA
G. Ha
POSTECH, Pohang, Kyungbuk, Republic of Korea

Funding: U.S. Dept of Energy Office of Science under contract number DE-AC02-06CH11357.
The Argonne Wakefield Accelerator 75 MeV drive beamline at Argonne National Laboratory has as its electron source a Cesium telluride photocathode gun with a vacuum requirement on the order of 10^-10 torr. In conflict with this, the experimental program at AWA sometimes requires beamline installation of experimental structures which due to materials and/or construction cannot meet the stringent vacuum requirement. One solution is to sequester these types of structures inside a separate vacuum chamber and inject the beam through a thin Beryllium window. The downside is that multiple scattering effects degrade the beam quality to some degree which is not well-known. This study was done in an effort to better understand and predict the multiple scattering effects of the Be thin window, particularly on the beam transverse size. The results of measurements are compared with GEANT4 Monte Carlo simulations via G4beamline and analytical calculations via GPT.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPTY022

Modifications of Superconducting Properties of Niobium Caused by Nitrogen Doping Recipes for High Q Cavities

niobium, SRF, cavity, superconductivity

3312

A. Vostrikov, M. Checchin, A. Grassellino, A. Romanenko
Fermilab, Batavia, Illinois, USA
Y.K. Kim, A. Vostrikov
University of Chicago, Chicago, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Discovery at Fermilab of a drastic effect of nitrogen doping leading to unprecedented high Q values in niobium cavities * motivated a strong interest in revealing the physics underlying the effect. In this contribution we present new results obtained by DC magnetometry, AC susceptibility, resistivity and thermal properties measurements on nitrogen doped samples prepared by different recipes/doping levels, which shed light on the possible origin of the effect.
* A. Grassellino et al, 2013 Supercond. Sci. Technol. 26 102001

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY022

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPTY023

LBNF 1.2 MW Target: Conceptual Design & Fabrication

target, operation, alignment, monitoring

3315

C.F. Crowley, K. Ammigan, K. Anderson, B.D. Hartsell, P. Hurh, J. Hylen, R.M. Zwaska
Fermilab, Batavia, Illinois, USA

Fermilab’s Long-Baseline Neutrino Facility (LBNF) will utilize a modified design based on the NuMI low energy target that is reconfigured to accommodate beam operation at 1.2 MW. Achieving this power with a graphite target material and ancillary systems originally rated for 400 kW requires several design changes and R&D efforts related to material bonding and electrical isolation. Target cooling, structural design, and fabrication techniques must address higher stresses and heat loads that will be present during 1.2 MW operation, as the assembly will be subject to cyclic loads and thermal expansion. Mitigations must be balanced against compromises in neutrino yield. Beam monitoring and subsystem instrumentation will be updated and added to ensure confidence in target positioning and monitoring. Remote connection to the target hall support structure must provide for the eventual upgrade to a 2.4 MW target design, without producing excessive radioactive waste or unreasonable exposure to technicians during reconfiguration. Current designs and assembly layouts will be presented, in addition to current findings on processes and possibilities for prototype and final assembly fabrication.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY023

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPTY026

Design of a Compact Fatigue Tester for Testing Irradiated Materials

operation, status, alignment, shielding

3321

B.D. Hartsell, M.R. Campbell, P. Hurh
Fermilab, Batavia, Illinois, USA
M.D. Fitton
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
T. Ishida, T. Nakadaira
KEK, Ibaraki, Japan

A compact fatigue testing machine that can be easily inserted into a hot cell for characterization of irradiated materials is beneficial to help determine relative fatigue performance differences between new and irradiated material. Hot cell use has been carefully considered by limiting the size and weight of the machine, simplifying sample loading and test setup for operation via master-slave manipulator, and utilizing an efficient design to minimize maintenance. Funded from a US-Japan collaborative effort, the machine has been specifically designed to help characterize titanium material specimens. These specimens are flat cantilevered beams for initial studies, possibly utilizing samples irradiated at other sources of beam. The option to test spherically shaped samples cut from the T2K vacuum window is also available. The machine is able to test a sample to 10⁷ cycles in under a week, with options to count cycles and sense material failure. The design of this machine will be presented along with current status.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY026

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPTY030

Breakdown Characterization in 805 MHz Pillbox-like Cavity in Strong Magnetic Fields

cavity, site, electron, pick-up

3335

A.V. Kochemirovskiy, D.L. Bowring, A. Moretti, D.W. Peterson, K. Yonehara
Fermilab, Batavia, Illinois, USA
M. Chung
UNIST, Ulsan, Republic of Korea
G. Flanagan, G.M. Kazakevich
Muons, Inc, Illinois, USA
B.T. Freemire
IIT, Chicago, Illinois, USA
A.V. Kochemirovskiy
University of Chicago, Chicago, Illinois, USA
Y. Torun
Illinois Institute of Technology, Chicago, Illlinois, USA

RF Breakdown in strong magnetic fields has a negative impact on a cavity performance. The MuCool Test Area at Fermilab has unique capabilities that that allow us to study the effects of static magnetic field on RF cavity operation. We have tested an 805 MHz pillbox-like cavity in external magnetic fields up to 5T. Results confirm our basic model of breakdown in strong magnetic fields. We have measured maximum achievable surface gradient dependence on external static magnetic field. Damage inspection of cavity walls revealed a unique observed breakdown pattern. We present the analysis of breakdown damage distribution and propose the hypothesis to explain certain features of this distribution

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY030

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPTY032

MICE Cavity Installation and Commissioning/Operation at MTA

cavity, operation, instrumentation, solenoid

3342

M.A. Leonova, M. Backfish, D.L. Bowring, A.V. Kochemirovskiy, A. Moretti, D.W. Peterson, M. Popovic, Y. Torun, K. Yonehara
Fermilab, Batavia, Illinois, USA
B.T. Freemire
IIT, Chicago, Illinois, USA
C. Hunt
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
P.G. Lane
Illinois Institute of Technology, Chicago, Illinois, USA
T.H. Luo
LBNL, Berkeley, California, USA
D.C. Speirs, C.G. Whyte
USTRAT/SUPA, Glasgow, United Kingdom
T. Stanley
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom

A first electropolished 201-MHz RF cavity for the international Muon Ionization Cooling Experiment (MICE) has been assembled inside a special vacuum vessel and installed at the Fermilab's MuCool Test Area (MTA). The cavity and the MTA hall have been equipped with numerous instrumentation to characterize cavity operation. The cavity has been commissioned to run at 14 MV/m gradient with no external magnetic field; it is also being commissioned in presence of fringe field of a multi-Tesla superconducting solenoid magnet, the condition in which cavity modules will be operated in the MICE cooling channel. The assembly, installation and operation of the Single-Cavity Module gave valuable experience for operation of full-size modules at MICE.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY032

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPTY035

Design and Test of the Compact Tuner for Narrow Bandwidth SRF Cavities

cavity, cryogenics, operation, SRF

3352

Y.M. Pischalnikov, E. Borissov, I.V. Gonin, J.P. Holzbauer, T.N. Khabiboulline, W. Schappert, S.J. Smith, J.C. Yun
Fermilab, Batavia, Illinois, USA

Funding: Fermi Research Alliance, LLC under Contract N. DE-AC02-07CH11359 with U.S. Department of Energy.
The design of the compact tuner for 1.3 GHz 9-cell elliptical cavity will be presented. This compact tuner is designed for future accelerators that will operate in CW and pulsed RF-power modes. The major design features include highly reliable active components (electromechanical actuators and piezo-actuators) and the ability to replace tuner active components through designated ports in the cryomodule vacuum vessel. Results of tuner testing with cold cavity will also be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY035

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPTY045

High-Intensity Proton RFQ Accelerator Fabrication Status for PXIE

rfq, cavity, alignment, quadrupole

3375

A.R. Lambert, A.J. DeMello, M.D. Hoff, D. Li, T.H. Luo, J.W. Staples, S.P. Virostek
LBNL, Berkeley, California, USA
R. Andrews, C.M. Baffes, P. Berrutti, T.N. Khabiboulline, G.V. Romanov, D. Snee, J. Steimel
Fermilab, Batavia, Illinois, USA

Funding: Work supported by the Office of Science, U.S. Department of Energy under DOE contract number DE-AC02-05CH11231
PXIE is a prototype front end system for the proposed PIP-II accelerator upgrade at Fermilab. An integral component of the front end is a 162.5 MHz, normal conducting, CW (continuous wave), radio-frequency quadrupole (RFQ) cavity that was designed and is being fabricated by LBNL. This RFQ will accelerate a continuous stream of up to 10mA of H⁻ ions from 30 keV to 2.1 MeV. The four-vane, 4.45 meter long RFQ consists of four modules, each constructed from 2 pairs of identical modulated vanes. Vane modulations are machined using a custom carbide cutter designed at LBNL. Other machined features include ports for slug tuners, pi-mode rods, sensing loops, vacuum pumps and RF couplers. Vanes at the entrance and exit possess cutbacks for RF matching to the end plates. The vanes and pi-mode rods are bonded via hydrogen brazing with Cusil wire alloy. The brazing process mechanically bonds the RFQ vanes together and vacuum seals the module along its length. Vane fabrication is successfully completed, and the braze process has proved successful. Delivery of the full RFQ beam-line is expected in the middle of 2015.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY045

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPTY055

Installation and Commissioning of the MICE RF Module Prototype

cavity, Windows, operation, coupling

3395

Y. Torun, P.G. Lane
Illinois Institute of Technology, Chicago, Illlinois, USA
T.G. Anderson, D.L. Bowring, M. Chung, J.H. Gaynier, M.A. Leonova, A. Moretti, R.J. Pasquinelli, D.W. Peterson, R.P. Schultz
Fermilab, Batavia, Illinois, USA
A.J. DeMello, D. Li, S.P. Virostek
LBNL, Berkeley, California, USA
L. Somaschini
INFN-Pisa, Pisa, Italy

Funding: Supported by the US Department of Energy Office of Science through the Muon Accelerator Program.
A special vacuum vessel prototype was built to house the first production 201 MHz RF cavity for the International Muon Ionization Cooling Experiment (MICE). The resulting prototype RF module has been assembled, instrumented, installed and commissioned at Fermilab's MuCool Test Area and the effort has provided valuable experience for the design of modules that will be used in the cooling channel for the experiment.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY055

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPTY061

Progress on the Cryogenic and Current Tests of the MSU Cyclotron Gas Stopper Superconducting Magnet

cyclotron, ion, cryogenics, dipole

3415

M.A. Green, G. Bollen, S. Chouhan, A.F. Zeller
FRIB, East Lansing, Michigan, USA
J. DeKamp, C. Magsig, D.J. Morrissey, J. Ottarson, S. Schwarz
NSCL, East Lansing, Michigan, USA

Funding: This work reported in this paper was supported in part by an NSF grant PHY-0958726
The Michigan State University (MSU) cyclotron gas stopper magnet is a warm iron superconducting cyclotron dipole. The desired field shape is obtained by the pole iron profile. Each coil of the two halves is in a separate cryostat and connected in series through a warm electrical connection. The entire system is mounted on a high voltage platform, and is cooled using six two-stage 4.2 K pulse tube coolers. This paper presents the progress on the magnet fabrication, cooling, and current testing.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY061

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPTY073

Update on Nitrogen Doping: Quench Studies and Sample Analysis

cavity, niobium, SRF, radiation

3450

D. Gonnella, F. Furuta, G.M. Ge, J.J. Kaufman, M. Liepe, J.T. Maniscalco
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: U.S. Department of Energy, NSF
Recently, nitrogen-doping of niobium has emerged as a promising preparation method for SRF cavities to reach higher intrinsic quality factors than can be reached with typical cavity preparation. Nitrogen-doped cavities prepared at Cornell have shown quality factors higher than 4x10¹⁰ at 2.0 K and 16 MV/m. While Q results have been very exciting, a reduced quench field currently limits nitrogen-doped cavities with quench typically occurring between 15 and 25 MV/m. Here we report on recent results from Cornell on single-cell and 9-cell cavities, focusing on new preparations and maximum and critical fields. First we discuss results from over-doping niobium with nitrgoen, baking nitrogen-doped cavities at 120C, and doping with Argon. For a subset of these cavities we show results from quench studies that have been completed using temperature mapping. Finally, we present the first measurements of the higher critical field, Hc2, for nitrogen-doped niobium samples.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY073

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWI006

Dither Coils for the SuperKEKB Fast Collision Feedback System

feedback, collider, coupling, multipole

3500

U. Wienands, S.D. Anderson, S.M. Gierman, M. Kosovsky, C.M. Spencer, M.K. Sullivan
SLAC, Menlo Park, California, USA
Y. Funakoshi, M. Masuzawa, T. Oki
KEK, Ibaraki, Japan

Funding: Work supported in part by US DOE and in part by the US-Japan collaboration agreement.
The collision feedback system for the SuperKEKB electron-positron collider at KEK will employ a dither feedback with a roughly 100 Hz excitation frequency to generate a signal proportional to the offset of the two beams. The excitation will be provided by a local bump across the interaction point (IP) that is generated by a set of eight air-core solid-wire magnet coil assemblies, each of which provides a horizontal and/or vertical deflection of the beam, to be installed around the vacuum system of the SuperKEKB Low Energy Ring. The design of the coils was challenging as large antechambers had to be accommodated and a 0.1% relative field uniformity across a good-field region of ±1 cm was aimed for, while keeping reasonable dimensions of the coils. This led to non-symmetric, non-flat designs of the coils. The paper describes the magnetic design and the method used to calculate the magnetic field of the coils, the mechanical design and the field measurement results. Tracking in the lattice model has indicated acceptable performance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI006

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWI011

Commissioning Results of Nb3Sn Cavity Vapor Diffusion Deposition System at JLab

cavity, niobium, SRF, network

3512

G.V. Eremeev, W.A. Clemens, K. Macha, H. Park, R.S. Williams
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Nb3Sn as a BCS superconductors with a superconducting critical temperature higher than that of niobium offers potential benefit in lower surface resistance at the same temperature and frequency for SRF cavities. A Nb3Sn vapor diffusion deposition system was built and commissioned at Jefferson Lab. As the part of the commissioning a single cell 1.5 GHz CEBAF-shaped cavity was coated in the built system. The cavity exhibited the superconducting transition at about 17.9 K. The low field quality factor was about 5x10⁹ at 4 K and 7x10⁹ at 2 K dropping with field to about 10⁹ at both temperatures at about 8 MV/m.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI011

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWI015

BNL 56 MHz HOM Damper Prototype Fabrication at JLab

niobium, cavity, HOM, network

3521

N.A. Huque, W.A. Clemens, E. Daly
JLab, Newport News, Virginia, USA
S. Bellavia, G.T. McIntyre, S.K. Seberg, Q. Wu
BNL, Upton, Long Island, New York, USA

A prototype Higher-Order Mode (HOM) Damper was fabricated at JLab for the Relativistic Heavy-Ion Collider’s (RHIC) 56 MHz cavity at Brookhaven National Laboratory (BNL). Primarily constructed from high RRR Niobium and Sapphire, the coaxial damper presented significant challenges in electron-beam welding (EBW), brazing and machining via acid etching. The results of the prototype operation brought about changes in the damper design, due to overheating braze alloys and possible multi-pacting. Five production HOM dampers are currently being fabricated at JLab. This paper outlines the challenges faced in the fabrication process, and the solutions put in place.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI015

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWI024

Vacuum Characterization and Improvement for the Jefferson Lab Polarized Electron Source

ion, electron, background, gun

3540

M.L. Stutzman, P.A. Adderley, M. Poelker
JLab, Newport News, Virginia, USA
M.A. Mamun
Old Dominion University, Norfolk, Virginia, USA

Operating the JLab polarized electron source with high reliability and long lifetime requires vacuum near the XHV level (<=1x10^-12 Torr). This paper describes ongoing vacuum research at Jefferson Lab including characterization of outgassing rates for surface coatings and heat treatments, ultimate pressure measurements, investigation of pumping including an XHV cryopump, and characterization of ionization gauges in this pressure regime.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI024

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWI033

Effects of Plasma Processing on Secondary Electron Yield of Niobium Samples

electron, plasma, cavity, gun

3558

M. Basovic, S. Popović, M. Tomovic, L. Vušković
ODU, Norfolk, Virginia, USA
F. Čučkov, A. Samolov
University of Massachusetts Boston, Boston, Massachusetts, USA

Impurities deposited on the surface of Nb during both the forming and welding of accelerator cavities add to the imperfections of the sheet metal, which then affects the overall performance of the cavities. This leads to a drop in the Q factor and limits the maximum acceleration gradient achievable per unit length of the cavities. The performance can be improved either by adjusting the fabrication and preparation parameters, or by mitigating the effects of fabrication and preparation techniques used. We have developed the experimental setup to determine Secondary Electron Yield (SEY) from the surface of Nb samples. Our aim is to show the effect of plasma processing on the SEY of Nb. The setup measures the secondary electron energy distribution at various incident angles as measured between the electron beam and the surface of the sample. The goal is to determine the SEY on non-treated and plasma treated surface of electron beam welded samples. Here we describe the experimental setup, plasma treatment device, and fabrication and processing of the Nb samples.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI033

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWI042

A Table-Top Alpha-Magnet

operation, power-supply, experiment, collimation

3584

A.V. Smirnov, R.B. Agustsson, T.J. Campese, Y.C. Chen, J.J. Hartzell, F.H. O'Shea, E. Spranza
RadiaBeam, Santa Monica, California, USA

Funding: Department of Energy, contract# DE- SC-FOA-0000760
A compact electromagnetic alpha-magnet design, engineering, and operation are presented. Initially the magnet has been designed for a low-energy, laser-free, coherent Cherenkov THz-sub-THz source. The source is designed and engineered in RadiaBeam in collaboration with ANL and integrated into the Injector Test Stand (ITS) of the Advanced Photon Source. The magnet having 15 cm depth, 14” height, and up to 4 T/m gradient features a rectangular yoke, two on-axis coils, and substantially truncated, partially non-hyperbolic poles. The tapered vacuum chamber for the magnet includes a motorized scraper and means of optical control. The novel and inexpensive design can be applied in relatively small, a few MeV facilities, where weight and dimensions are limited including free electron lasers, far infrared sources, inverse Compton sources of ultra-bright hard X-rays, as well as beam instrumentation for microbunching and phase-space manipulation (e.g., magnetic compression combined with round-to-flat beam transformation).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI042

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWI045

Status of Superconducting Traveling Wave Cavity for High Gradient Linac

cavity, accelerating-gradient, cryogenics, feedback

3591

R.A. Kostin, P.V. Avrakhov, A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA
T.N. Khabiboulline, Y.M. Pischalnikov, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

The use of a travelling wave (TW) accelerating structure with a small phase advance per cell instead of standing wave may provide a significant increase of accelerating gradient in a superconducting linear accelerator. The TW section achieves an accelerating gradient 1.2-1.4 times larger than TESLA-shaped standing wave cavities for the same surface electric and magnetic fields. The final stage of a 3-cell superconducting travelling wave cavity development is presented. This cavity will be tested in travelling wave regime at cryogenic temperature.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI045

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWI054

Design and Test of the RHIC CMD10 Abort Kicker

kicker, impedance, network, coupling

3612

H. Hahn, M. Blaskiewicz, K.A. Drees, W. Fischer, W. Meng, J.-L. Mi, C. Montag, C. Pai, J. Sandberg, N. Tsoupas, J.E. Tuozzolo, W. Zhang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Planned and unplanned thyratron pre-fire triggered beam dumps have been observed in the yellow ring that were associated with quenches of the superconducting main ring magnets as the proton intensities increased in the FY10¹³ run. The increasing vacuum level indicated beam induced kicker ferrite heating causing lower magnetic kick field at a nominal pulse current. In anticipation of higher current and shorter bunches in FY2015 an accelerator improvement program was initiated to reduce the longitudinal coupling impedance with changes to the eddy-current strip geometry using Opera simulations and to change the CMD5005 to CMD10 ferrite. Results of the standard impedance measurements and of pulse current in heating tests to 170 °C are reported. All 10 dump kickers are being modified and are encapsulated with a cooling system for installation in the rings.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI054

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPF006

Design and Manufacturing Status of the IFMIF-LIPAC SRF LINAC

cryomodule, cavity, linac, solenoid

3686

H. Dzitko
CEA, Pontfaverger-Moronvilliers, France
N. Bazin, A. Bruniquel, P. Charon, P. Gastinel, P. Hardy, H. Jenhani, J. Neyret, O. Piquet, J. Relland, N. Sellami
CEA/IRFU, Gif-sur-Yvette, France
S. Chel, G. Devanz, G. Disset, V.M. Hennion, B. Renard
CEA/DSM/IRFU, France
D. Gex, G. Phillips
F4E, Germany
D. Regidor, F. Toral
CIEMAT, Madrid, Spain

The IFMIF accelerator aims to provide an accelerator-based D-Li neutron source to produce high intensity high energy neutron flux for testing of candidate materials for use in fusion energy reactors. The first phase of the project, called EVEDA (Engineering Validation and Engineering Design Activities) aims at validating the technical options by constructing an accelerator prototype, called LIPAc (Linear IFMIF Prototype Accelerator) whose construction has begun. It is a full scale of one of the IFMIF accelerator from the injector to the first cryomodule. The cryomodule contains all the necessary equipment to transport and accelerate a 125 mA deuteron beam from an input energy of 5 MeV up to output energy of 9 MeV. It consists of a horizontal vacuum tank approximately 6 m long, 3 m high and 2.0 m wide, and includes 8 superconducting HWRs working at 175 MHz and at 4.45 K for beam acceleration. 8 Power Couplers provide RF power to the cavities up to 70 kW CW in the LIPAc case and 200 kW CW in the IFMIF case, with 8 Solenoid Packages acting as focusing elements. This paper gives an overview of the progress, achievements and status of the IFMIF SRF LINAC.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF006

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPF009

Pumping Properties of Cryogenic Surfaces in SIS100

cryogenics, simulation, operation, background

3696

L.H.J. Bozyk, O.K. Kester, P.J. Spiller
GSI, Darmstadt, Germany
F. Chill, O.K. Kester
IAP, Frankfurt am Main, Germany

Funding: Work supported by Hic4Fair and BMBF (FKZ:05P12RDRBK).
The synchrotron SIS100 of the planned FAIR facility will provide heavy ion beams of highest intensities. The required low charge states are subject to enhanced charge exchange processes in collisions with residual gas molecules. Therefore, highest vacuum quality is crucial for a reliable operation and minimal beam loss. The generation of the required low gas densities relies on the pumping capabilities of the cryogenic beam pipe walls. Most typical gas components in ultra high vacuum are bound by cryocondensation at LHe temperatures, resulting in ultimate low pressures with almost infinite pumping capacity. Hydrogen can not be crycondensated to acceptable low pressures. But if the surface coverage is sufficiently low, it can get bound by cryoadsorption. The pumping capabilities of cryogenic walls for Hydrogen have been investigated for SIS100-like conditions. The measurement results have been used in dynamic vacuum simulations at heavy ion operation. The simulation results are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF009

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPF012

Status of the High Energy Beam Transport System for FAIR

dipole, quadrupole, diagnostics, beam-diagnostic

3705

F. Hagenbuck, L.H.J. Bozyk, S. Damjanovic, A. Krämer, B. Merk, C. Mühle, S. Ratschow, B.R. Schlei, P.J. Spiller, B. Walasek-Höhne, H. Welker, C. Will
GSI, Darmstadt, Germany

The overall layout of the High Energy Beam Transport (HEBT) System of the Facility for Antiproton and Ion Research (FAIR)* did not change since its last presentation in 2008**. All necessitated adaptions as for example due to the introduction of the Modularized Start Version (MSV, module 0-3) of FAIR*** could be smoothly implemented. In the meanwhile the HEBT system is in its realisation phase with the procurement of its main components in progress. In the following adaptions of the system layout not yet covered in ** are summarized and an overview of the technical system design and procurement status are presented.
* FAIR Baseline Technical Report (FBTR), GSI 2006
** S. Ratschow et al., Proc. of EPAC08, THPP104, Genoa, Italy (2008)
***FAIR Green Paper - The Modularized Start Version, October 2009

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPF023

Massless Beam Separation System for Intense Ion Beams

septum, shielding, dipole, beam-transport

3736

O. Payir, M. Droba, O. Meusel, D. Noll, U. Ratzinger, P.P. Schneider, C. Wiesner
IAP, Frankfurt am Main, Germany

The ExB chopper* in the Low Energy Beam Transport (LEBT) section of the accelerator-driven neutron source FRANZ** will form the required pulses with a repetition rate of 257 kHz out of the primary 120 keV, 50 mA DC proton beam. A following beam separation system will extract the deflected beam out of the beamline and minimize the thermal load by beam losses in the vacuum chamber. To further avoid an uncontrolled production of secondary particles, a novel massless septum system is designed for the beam separation. The septum system consists of a static C-magnet with optimized pole shapes, which will extract the beam with minimal losses, and a magnetic shielding tube, which will shield the transmitted pulsed beam from the fringing field of the dipole. The magnetic field and the beam transport properties of the system were numerically investigated. A main deflection field of about 250 mT was achieved, whereas the fringing field was reduced to below 0.3 mT on the beam axis at 60 mm distance from the dipole. With this settings, the beam was numerically transported through the system with minimal emittance growth. Manufacturing of the septum system has started.
* Wiesner, C., et al. "Chopping High-Intensity Ion Beams at FRANZ", WEIOB01, LINAC 2014.
** Meusel, O., et al. "FRANZ–Accelerator Test Bench And Neutron Source", MO3A03, LINAC 2012.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF023

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPF034

Injection Kicker for HESR at FAIR using Semi-Conductor Switches

injection, kicker, antiproton, impedance

3770

R. Tölle, N. Bongers, F.M. Esser, R. Gebel, S. Hamzic, H. Jagdfeld, F. Klehr, B. Laatsch, L. Reifferscheidt, M. Retzlaff, L. Semke, H. Soltner, H. Stockhorst
FZJ, Jülich, Germany
S. Antoine, W. Beeckman, P. Bocher, O. Cosson, P. Jivkov, D. Ramauge
Sigmaphi, Vannes, France

The High Energy Storage Ring for Antiprotons is going to be built at FAIR in Darmstadt on the extended GSI campus. It will receive the antiprotons via the Collector Ring (CR). Using a barrier bucket, the circulating particles will be compressed into one half of the circumference. New particles have to be injected into the remaining half. Thus rise and fall time must not exceed 220 ns each with a flat top of 500 ns. A kick angle of 6.4 mrad is required at 13 Tm magnetic rigidity. The system must allow pole reversal for injection of positively charged particles. With a voltage lower than 40 kV a semi-conductor based pulser is going to be realized. Boundary conditions and the status of preparatory work are described. Simulation results and available measurements are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF034

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPF044

Status of the J-PARC 3 GeV RCS

operation, injection, linac, radiation

3798

M. Kinsho
JAEA/J-PARC, Tokai-mura, Japan

Beam injection energy of the RCS in J-PARC was increased from 181 MeV to 400 MeV, and user operation with beam energy of 300 kW for both the MLF and the MR was performed with high availability from February to Jun in 2014. Beam losses during beam injection period was decreased by reduction of space charge effect due to increase of beam injection energy. Since an ion source and an RFQ of the LINAC are replaced to realize 1 MW beam power at the RCS in summer maintenance period, injection beam peak current was increased from 30 mA to 50 mA. User operation was restarted from November with beam power of 300 kW. The beam power for user operation will be gradually increased after getting radiation safety permission from government. High intensity beam study was also performed and it was successfully to accelerate beam of 770 kW equivalent without beam loss except foil scattering loss. In this beam study it was cleared issues to realize 1MW operation in the RCS. Status of user operation and issues to realize high power operation in the RCS are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF044

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPF069

The Early Results of the Vertical Test for β=0.12 HWR at RISP

cavity, coupling, cryogenics, niobium

3839

G.-T. Park, H.J. Cha, H.C. Jung, H. Kim, W.K. Kim, Y.J.K. Kim
IBS, Daejeon, Republic of Korea

At RISP, we are planning to perform the vertical test of the β=0.12 half wave resonator. We report our progress on the preparation of the test including the cryogenic system, the RF system, the control and data acquisition system, and the radiation shields. We had the first few occaaisions of the cool down and various measurements at a low gradient. Out preliminary result on the Q₀-E_acc excitation curve will be given.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF069

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPF070

Prototyping Progress of SSR1 Single Spoke Resonator for RAON

cavity, target, simulation, ion

3842

H.J. Cha, H. Kim, H.J. Kim, W.K. Kim, G.-T. Park
IBS, Daejeon, Republic of Korea

The fabrication of prototypes for four different types of superconducting cavities (QWR, HWR, SSR1, and SSR2) for the Korean heavy ion accelerator, “RAON” is in progress. In this presentation, we report the current status of the SSR1 cavity (β=0.3 and f=325 MHz) prototype fabrication based on the technical designs. The simulation results on the target frequency determination for the clamp-up test of the prototype are also given.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF070

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPF075

Proton Beam of 2 MeV 1.6 mA on a Tandem Accelerator with Vacuum Insulation

neutron, proton, ion, high-voltage

3854

S.Yu. Taskaev, D.A. Kasatov, A.S. Kuznetsov, A.N. Makarov, I.M. Shchudlo, I.N. Sorokin
BINP SB RAS, Novosibirsk, Russia

Funding: The research is conducted with the financial support of the Ministry of Education and Science of the Russian Federation (a unique identifier for applied scientific research – RFMEFI60414X0066).
New type of charged particles accelerator, tandem accelerator with vacuum insulation, was proposed in BINP. The accelerator is characterized by fast acceleration of charged particles, long distance between ion beam and insulator (on which electrodes are mounted), big stored energy in the accelerating gaps and strong input electrostatic lens. High-voltage strength of vacuum gaps, dark currents, ion beam focusing, accelerating and stripping were investigated. Stationary proton beam with 2 MeV energy, 1.6 mA current has just been obtained. The beam is characterized by high energy monochromaticity – 0.1%, and high current stability – 0.5%. Here we report the results of these investigations and discuss the proposal for obtaining 2.5 MeV 3 mA proton beam. The accelerator is considered to be a part of epithermal neutron source for boron neutron capture therapy and monoenergetic neutron source for calibration of dark matter detector.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF075

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPF086

A New Hardware Design for PSB Kicker Magnets (KSW) for the 35 mm Transverse Painting in the Horizontal Plane

injection, kicker, linac, emittance

3890

L.M.C. Feliciano, C. Bracco, L. Ducimetière, T. Fowler, G. Gräwer, R. Noulibos, L. Sermeus, W.J.M. Weterings, C. Zannini
CERN, Geneva, Switzerland

The changeover from Linac2 to Linac4 in CERN’s injector chain will allow increasing the injection energy into the PS Booster from 50 MeV to 160 MeV. Transverse phase space painting will be performed in the horizontal plane, by means of four stacks of four KSW kicker magnets. The KSW magnets are located outside the injection region and will produce a 35 mm closed orbit bump, with falling amplitude during the injection to accomplish transverse phase space painting to the required emittance. New magnets with two different types of coils are being built using the existing design. The magnets are made of two halves, which are assembled together around a vacuum ceramic chamber. In order to reduce the beam impedance, the ceramic chamber is internally coated by a thin titanium layer. A new multiple-linear waveform generator has been developed to provide the high flexibility in the KSW kicker magnets current decay to fulfil the requirements of all the different users (LHC, nTOF, ISOLDE, CNGS, etc.).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF086

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPF096

Origin of the Damage to the Internal High Energy Beam Dump in the CERN SPS

proton, simulation, kicker, dumping

3927

V. Kain, K. Cornelis, B. Goddard, M. Lamont, I.V. Leitao, R. Losito, C. Maglioni, M. Meddahi, F. Pasdeloup, G.E. Steele, F.M. Velotti
CERN, Geneva, Switzerland

The high energy beam dump in the SPS has to deal with beams from 10⁵ to 450 GeV/c and intensities of up to 4 ×10¹³ protons. An inspection during the last shutdown revealed significant damage to the Al section of the dump block. This paper summarizes the results of the analysis revealing the most likely cause of the damage to the beam dump. The implications for future SPS operation will also be briefly discussed, together with the short-term solution put in place.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF096

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPF149

Electromagnetic Modeling of 4-Rod RFQ Tuning

rfq, simulation, quadrupole, linac

4076

S.S. Kurennoy, L. Rybarcyk
LANL, Los Alamos, New Mexico, USA

Modern codes make possible detailed 3D electromagnetic modeling of RFQ accelerators. We have recently analyzed two 201.25-MHz 4-rod RFQs – one commissioned at FNAL and a new design for LANL – with CST Studio using imported manufacturer CAD files*. The RFQ electromagnetic analysis with MicroWave Studio (MWS) was followed by beam dynamics modeling with Particle Studio as well as other multi-particle codes. Here we apply a similar approach to study the process of RFQ tuning in 3D CST models. In particular, the results will be used to better understand tuning the voltage flatness along the new LANL 4-rod RFQ.
* S.S. Kurennoy, LINAC14, Geneva, Switzerland, 2014, THPP097.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF149

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)