IPAC2015 - List of Keywords (factory)

Paper	Title	Other Keywords	Page
MOPWA003	Optimal Generalized Finite Difference Solution to the Particle-in-Cell Problem	framework, simulation, plasma, space-charge	77
	X. Wang, X. Jiao, H. Liu, V. Samulyak, K. Yu SBU, Stony Brook, USA V. Samulyak BNL, Upton, Long Island, New York, USA
	The particle-in-cell (PIC) method is widely used in applications, such as in electromagnetics, but the accuracy of its solutions degrades when the particle distribution is highly non-uniform. In our work, we propose an adaptive PIC method with optimal point distribution and a generalized finite difference (GFD) scheme. Our method replaces the Cartesian grid in the classical PIC with adaptive computational nodes or particles, to which the charges from the sample particles are assigned by a weighted least-square approximations. The partial differential equation is then discretized using a GFD method and solved with fast linear solvers. The density of computational particles is chosen adaptively, so that the error from GFD and that from Monte Carlo integration are balanced and the total error is approximately minimized. We also present the verification results using electrostatic problems and comparison of accuracy and solution time of our method with the classical PIC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA003
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MOPWA018	Loss Factor and Impedance Analysis of Warm Components of BERLinPro	impedance, simulation, operation, wakefield	128
	H.-W. Glock, M. Abo-Bakr, J. Kolbe, F. Pflocksch, A. Schälicke HZB, Berlin, Germany H.-W. Glock, C. Potratz COMPAEC e.G., Rostock, Germany
	Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association The ongoing component design for the HZB 50 MeV, 100mA ERL project BERLinPro is accompanied by loss factor and impedance computations. A list of accelerator components including bellows, collimators, tapers, shutter valves etc. is given, some of them with alternative shapes. Loss factors, calculated using CSTParticleStudio®, are presented together with important properties of the impedance spectrum. Scaling of the loss factors with respect to bunch length is calculated on base of the numerical simulations and is used to extrapolate down to a bunch length (1 standard deviation) of 0.6 mm, which is hard to reach directly in numerical simulations.
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MOPWA062	Optimization of the Momentum Bandwidth for Final Focus System in CEPC	sextupole, luminosity, collider, simulation	269
	S. Bai, T.J. Bian, J. Gao, H. Geng, D. Wang, Y. Wang, M. Xiao IHEP, Beijing, People's Republic of China F. Su Institute of High Energy Physics (IHEP), People's Republic of China
	With the discovery of the higgs boson at around 125GeV, a circular higgs factory design with high luminosity (L ~ 10³⁴ cm^-2s^-1) is becoming more popular in the accelerator world. To achieve such high luminosity, a final focus system in non-local chromaticity correction scheme with very low β functions at the interaction point is designed. The narrow momentum bandwidth is a crucial problem of this kind of design. It is shown that by introducing additional sextupoles the momentum acceptance of the CEPC final focus system can be increased by about a factor of four.
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MOPJE055	Design of an Intense Muon Source with a Carbon and Mercury Target	target, proton, collider, solenoid	423
	D. Stratakis, J.S. Berg BNL, Upton, Long Island, New York, USA X.P. Ding UCLA, Los Angeles, California, USA D.V. Neuffer Fermilab, Batavia, Illinois, USA
	Funding: Authored by employees of Brookhaven Science Associates LLC under Contract DE-SC0012704 and with Fermi Research Alliance LLC under Contract DE-AC02-07CH11359 with the United States Department of Energy In high-intensity sources, muons are produced by firing high energy protons onto a target to produce pions. The pions decay to muons which are captured and accelerated. In the present study, we examine the performance of the channel for two different target scenarios: one based on liquid mercury and another one based on a solid carbon target. We produce distributions with the two different target materials and discuss differences in particle spectrum near the sources. We then propagate the distributions through our capture system and compare the full system performance for the two target types.
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MOPJE076	Multi-objective Genetic Optimization with the General Particle Tracer (GPT) Code	solenoid, emittance, cavity, target	492
	S.B. van der Geer, M.J. de Loos Pulsar Physics, Eindhoven, The Netherlands
	In a typical design process there are a large number of variables, external constraints, and multiple conflicting objectives. Examples of the latter are short pulse, high charge, low emittance and low price. The classical solution to handle such problems is to combine all objectives into one merit function. This however implicitly assumes that the tradeoffs between all objectives are a-priori known. Especially in the early design stages this is hardly ever the case. A popular solution to this problem is to switch to multi-objective genetic optimization algorithms. This class of algorithms solves the problem by genetically optimising an entire population of sample solutions. Selection and recombination operators are defined such that the output, the so-called Pareto front, only includes solutions that are fully optimized where no objective can be improved without degrading any other. Here we present numerical studies and practical test runs of the genetic optimizer built into the General Particle Tracer (GPT) code.
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MOPMA011	Evaluation of Power Supply and Alignment Tolerances for the Advanced Photons Source Upgrade	dipole, sextupole, quadrupole, power-supply	556
	V. Sajaev 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. The hybrid seven-bend-achromat lattice that has been proposed for the Advanced Photon Source upgrade will feature very strong focusing elements and will provide an electron beam with very low emittance. In order to be able to maintain stable operation, very tight tolerances are required for various types of errors. Here we describe evaluation of the effects of various errors including magnet power supplies, alignment, and vibration. Based on this analysis, we determine short- and long-term stability requirements
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MOPTY062	The Energy Saving Processes for Utility System in TPS	controls, experiment, operation, photon	1082
	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
	There are more and more non-linear electronic equipments such as inverters using in facility nowadays. These non-linear electronic equipments let us achieve energy saving, but induce other electrical pollution to the whole power grid in contrast. Among these electrical pollutions, electric harmonic is the most common and harmful to power facility. Therefore, how to monitor the electrical noises from these non-linear equipments becomes an important issue. In this article, a set of power quality monitoring system based on FPGA (Field-Programmable Gate Arrays) modules and PAC (Programmable Automatic Controller) has been built because of their programmability and fast processing speed. By using this monitoring system, any abnormality in power system and its spectrum will be recorded thoroughly. On the other hand, the maintainer could follow the trace of noise and then propose a suitable solution to eliminate the electrical interference too.
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TUPWA055	DAΦNE Gamma-Ray Factory	electron, laser, photon, emittance	1542
	D. Alesini, S. Guiducci, C. Milardi, A. Variola, M. Zobov INFN/LNF, Frascati (Roma), Italy I. Chaikovska, Z.F. Zomer LAL, Orsay, France
	Gamma sources with high flux and spectral densities are the main requirements for new nuclear physics experiments to be performed in several worldwide laboratories with dedicated facilities. The presentation is focalized on a proposal of experiment of gamma photons production using Compton collisions between the DAΦNE electron beam and a high average power laser pulse, amplified in a Fabry-Pérot optical resonator. The calculations show that the resulting gamma beam source has extremely interesting properties in terms of spectral density, energy spread and gamma flux comparable (and even better) with the last generation gamma sources. The energy of the gamma beam depends on the adopted laser wavelength and can be tuned changing the energy of the electron ring. In particular we have analyzed the case of a gamma factory tunable in the 2-9 MeV range. The main parameters of this new facility are presented and the perturbation on the transverse and longitudinal electron beam dynamics is discussed. A preliminary accelerator layout to allow experiments with the gamma beam is presented with a first design of the accelerator optics.
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TUPJE017	The Generation of Highly Intense THz Radiation based on Smith-Purcell Radiation	radiation, electron, gun, cathode	1654
	Y.F. Xu, Z.G. He, Q.K. Jia, W.W. Li USTC/NSRL, Hefei, Anhui, People's Republic of China
	A photocathode RF gun can generate trains of THz subpicosecond electron bunches by illuminating the cathode with trains of laser pulses. Let this electron bunches passes close to the surface of a lamellar grating, THz radiation will be emitted, which is the so-called Smith-Purcell Radiation (SPR). If the lamellar grating has a narrow groove, this radiation will be narrow-band. By choosing suitable parameter, the SPR frequency can be resonant with the electron bunches frequency, and then generate high intense, narrow band THz radiation.
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TUPTY012	Orbit Correction in CEPC	quadrupole, dipole, closed-orbit, target	2022
	S. Bai, J. Gao, H. Geng IHEP, Beijing, People's Republic of China
	With the discovery of the higgs boson at around 125GeV, a circular higgs factory design with high luminosity (L ~ 10³⁴ cm^-2s^-1) is becoming more popular in the accelerator world. The CEPC project in China is one of them. To reduce the cost, pretzel scheme was considered in CEPC orbit design. The presence of every kind of errors and misalignments will destroy the pretzel orbit. In this paper, we correct the distorted pretzel orbit in the CEPC main ring using the dipole correctors and beam position monitors. The pretzel orbit was recovered and the maximum corrector strengths are got.
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TUPTY057	Scenarios for Circular Gamma-Gamma Higgs Factories	collider, laser, luminosity, electron	2156
	F. Zimmermann, Y. Papaphilippou CERN, Geneva, Switzerland R. Aleksan CEA/DSM/IRFU, France A. Apyan NU, Evanston, Illinois, USA
	Funding: The research leading to these results has received partial funding from the European Commission under the FP7 Research Infrastructures project EuCARD-2, grant agreement no.312453. The Higgs boson can be produced directly in gamma-gamma collisions generated by laser Compton back scattering off 80-90 GeV electron or positron beams. We discuss options for realizing a gamma-gamma Higgs factory using a high-energy circular e⁺e⁻ collider, such as FCC-ee or CEPC, and/or its top-up injector ring, and compare the parameters and advantages of such a facility, including the expected performance, with those for a Higgs factory based on a recirculating linac, such as SAPPHiRE.
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WEBB3	Lattice and its Related Beam Dynamics Issues in the CEPC Storage Ring	lattice, quadrupole, electron, positron	2469
	H. Geng, S. Bai, Z. Duan, Y.M. Peng, Q. Qin, D. Wang, Y. Wang, G. Xu, Y. Yue, Y. Zhang IHEP, Beijing, People's Republic of China W. Chou Fermilab, Batavia, Illinois, USA
	The institute of High Energy Physics has proposed an electron positron collider ring with a circumference of 50-100km to study the Higgs boson. Since the proposal was made, the lattice design for CEPC has been carried out and a preliminary conceptual design report has been written at the end of 2014. In this paper, we will describe the philosophy and results of our lattice design. The procedure of dynamic aperture optimization will be shown. A specific issue for CEPC, the pretzel orbit, which has been found distorting the linear lattice for a considerable amount, will be examined. The ways that we are trying to correct the pretzel orbit effect and the result will be shown. We will also discuss the saw tooth effect on the linear lattice and dynamic aperture of the ring.
	Slides WEBB3 [2.599 MB]
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WEBD2	Survey of Commissioning of Recent Storage Ring Light Sources	survey, synchrotron, vacuum, 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]
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WEPWA043	Progress on the Design of the Racetrack FFAG Decay Ring for nuSTORM	lattice, detector, closed-orbit, resonance	2594
	J.-B. Lagrange, J. Pasternak Imperial College of Science and Technology, Department of Physics, London, United Kingdom R.B. Appleby, J.M. Garland, H.L. Owen, S.C. Tygier UMAN, Manchester, United Kingdom R.B. Appleby Cockcroft Institute, Warrington, Cheshire, United Kingdom Y. Mori Kyoto University, Research Reactor Institute, Osaka, Japan
	The neutrino beam produced from muons decaying in a storage ring would be an ideal tool for precise neutrino cross section measurements and search for sterile neutrinos due to its precisely known flavour content and spectrum. In the proposed nuSTORM facility pions would be directly injected into a storage ring, where circulating muon beam would be captured. The racetrack FFAG (Fixed Field Alternating Gradient) option for nuSTORM decay ring offers a very good performance due to a large dynamic and momentum acceptance. Machine parameters, linear optics design, beam dynamics and injection system for nuSTORM FFAG ring are discussed in this paper.
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WEPWA057	Design Concepts for Muon-Based Accelerators	collider, simulation, target, proton	2633
	R.D. Ryne LBNL, Berkeley, California, USA Y.I. Alexahin, A.D. Bross, K. E. Gollwitzer, N.V. Mokhov, D.V. Neuffer, M.A. Palmer, K. Yonehara Fermilab, Batavia, Illinois, USA J.S. Berg, H.G. Kirk, R.B. Palmer, D. Stratakis BNL, Upton, Long Island, New York, USA S.A. Bogacz JLab, Newport News, Virginia, USA J.-P. Delahaye SLAC, Menlo Park, California, USA T.J. Roberts Muons, Inc, Illinois, USA P. Snopok Illinois Institute of Technology, Chicago, Illinois, USA
	Muon-based accelerators have the potential to enable facilities at both the Intensity and the Energy Frontiers. Muon storage rings can serve as high precision neutrino sources, and a muon collider is an ideal technology for a TeV or multi-TeV collider. Progress in muon accelerator designs has advanced steadily in recent years. In regard to 6D muon cooling, detailed and realistic designs now exist that provide more than 5 order-of-magnitude emittance reduction. Furthermore, detector performance studies indicate that with suitable pixelation and timing resolution, backgrounds in the collider detectors can be significantly reduced thus enabling high quality physics results. Thanks to these and other advances in design & simulation of muon systems, technology development, and systems demonstrations, muon storage-ring-based neutrino sources and a muon collider appear more feasible than ever before. A muon collider is now arguably among the most compelling approaches to a multi-TeV lepton collider. This paper summarizes the current status of design concepts for muon-based accelerators for neutrino factories and a muon collider.
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WEPJE010	Particle Production of a Graphite Target System for the Intensity Frontier	target, proton, emittance, collider	2692
	X.P. Ding UCLA, Los Angeles, California, USA H.G. Kirk BNL, Upton, Long Island, New York, USA K.T. McDonald PU, Princeton, New Jersey, USA
	A solid graphite target system is considered for an intense muon and/or neutrino source in support of physics at the intensity frontier. We previously optimized the geometric parameters of the beam and target to maximize particle production at low energies by incoming protons with kinetic energy of 6.75 GeV and an rms geometric emittance of 5 mm-mrad using the MARS15(2014) code. In this study, we ran MARS15 with ROOT-based geometry and also considered a mercury-jet target as an upgrade operation. The optimization was extended to focused proton beams with transverse emittances from 5 to 50 mm-mrad, showing that the particle production decreases slowly with increasing emittance. We also studied the beam dump configuration to suppress the rate of undesirable higher-energy secondary particles in the beam.
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WEPMA026	Higher Order Mode Propagation and Damping Studies on Axisymmetric Superconducting Multicell RF-Resonators	cavity, damping, higher-order-mode, coupling	2812
	B.D. Isbarn, B. Riemann, M. Sommer, T. Weis DELTA, Dortmund, Germany
	Funding: Work supported by the BMBF under contract no. 05K13PEB Higher order mode (HOM) propagation and damping is a major concern in feasibility studies regarding the upcoming upgrade of BESSY II, named BESSY-VSR, which involves the utilization of superconducting multicell RF-resonators in a storage ring while maintaining a reasonably high beam current typical for third generation synchrotron radiation facilities. In addition to the computation of the typical figures of merit, we focus on studies of the mode propagation in axisymmetric structures. Due to the focus on axisymmetric studies we are able to use 2D codes to investigate in eigenmodes with substantial higher frequencies than usually considered with full 3D codes in parametric studies. In this work we present preliminary studies involving mode propagation in superconducting elliptical multicell cavities. G. Wüstefeld et al., Proc. of IPAC'11, San Sebastián, THPC014
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WEPMN055	RAMI Optimization-Oriented Design For The LIPAc RF Power System	controls, rf-amplifier, target, diagnostics	3048
	M. Weber, J.M. Arroyo, A. Ibarra, I. Kirpitchev, J. Mollá, P. Méndez, D. Regidor, C. de la Morena CIEMAT, Madrid, Spain
	Funding: This work has been funded by the Spanish Ministry of Economy and Competitiveness. The Linear IFMIF Prototype Accelerator (LIPAc) is currently under construction in Rokkasho (Japan). LIPAc will generate a CW 9 MeV deuteron beam at 125 mA. It will serve to validate the final IFMIF accelerator concept and technologies. The RF power system is being integrated by CIEMAT (Spain) in collaboration with its partner companies and European institutes. LIPAc RF Power System design has been performed aiming high reliability, high availability and easy maintainability to address one of the most important requirements for IFMIF. The target of LIPAc tests is to validate the technologies and designs for the final phase of IFMIF. Several improvements in reliability, availability and maintainability have been implemented in the LIPAc RF power System. These improvements are based on both, new technologies and new maintenance philosophy. The results of their first tests are shown in this paper. Additional potential improvements are also analyzed.
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WEPHA024	Preliminary Design of a Perpendicular Biased Ferrite Loaded Accelerating Cavity	cavity, simulation, resonance, operation	3163
	J. Eberhardt, F. Caspers, C. Vollinger CERN, Geneva, Switzerland
	A ferrite loaded accelerating cavity with a frequency sweep of 18 to 40 MHz is studied for a possible upgrade of the CERN accelerator complex. The resonance frequency of a ferrite loaded cavity shifts by applying an external magnetic bias field to the ferrite material by means of changing the relative permeability. We present the electromagnetic design of such a cavity with a special emphasis on the modeling of the nonlinear, anisotropic and dispersive characteristics of the ferrite’s relative permeability above magnetic saturation. For experimental crosscheck, a ferrite loaded resonant test setup was built which provides results for the material performance in a magnetic bias field. A comparison of numerical simulations and experimental measurements is shown and calculations are benchmarked by measurement data. Based on this study a preliminary design of a ferrite loaded accelerating cavity is described.
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WEPHA053	Surface Resistance RF Measurements of Materials Used for Accelerator Vacuum Chambers	cavity, coupling, resonance, network	3235
	P. Goudket, L. Gurran, O.B. Malyshev, M.D. Roper, R. Valizadeh, S. Wilde STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom G. Burt, L. Gurran Cockcroft Institute, Lancaster University, Lancaster, United Kingdom P. Goudket, O.B. Malyshev, R. Valizadeh Cockcroft Institute, Warrington, Cheshire, United Kingdom S. Wilde Loughborough University, Loughborough, Leicestershire, United Kingdom
	The RF surface resistance of accelerator vacuum chamber walls can have a significant impact on the beam quality. There is a need to know how the use of a new material, surface coating or surface treatment can affect the RF surface resistance. ASTeC and Lancaster University have designed and built two test cavities where one face can be replaced with a sample in the form of a flat plate. The measurements are performed with a network analyser at the resonant frequency of approximately 7.8 GHz.
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WEPTY034	T-map Studies on Gradient-limiting Mechanism in Nitrogen Doped Cavities	cavity, niobium, superconductivity, SRF	3348
	M. Martinello, M. Checchin, A. Grassellino, A. Romanenko Fermilab, Batavia, Illinois, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. Nitrogen doping * results in ultra-high quality factors in SRF niobium cavities but currently achievable gradients in doped cavities are, on average, somewhat lower than in EP/120C baked cavities. The origin of this difference is explored in the reported work by detailed temperature mapping studies on several single cell nitrogen doped cavities. * A. Grassellino et al, 2013 Supercond. Sci. Technol. 26 102001
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WEPTY050	Low Powered RF Measurements of Dielectric Materials for use in High Pressure Gas Filled RF Cavities	cavity, simulation, radio-frequency, collider	3387
	B.T. Freemire IIT, Chicago, Illinois, USA G. Arriaga Northern Illinois Univerity, Dekalb, Illinois, USA D.L. Bowring, A.V. Kochemirovskiy, A. Moretti, A.V. Tollestrup, Y. Torun, K. Yonehara Fermilab, Batavia, Illinois, USA H.D. Phan McDaniel College, Westminster, USA Y. Torun Illinois Institute of Technology, Chicago, Illlinois, USA
	The Helical Cooling Channel scheme envisioned for a Muon Collider or Neutrino Factory requires high pressure gas filled radio frequency cavities to operate in superconducting magnets. One method to shrink the radii of the cavities is to load them with a dielectric material. The dielectric constant, loss tangent, and dielectric strength are important in determining the most suitable material. Low powered RF measurements of the dielectric constant and loss tangent were taken for multiple purities of alumina and magnesium calcium titanate, as well as cordierite, forsterite, and aluminum nitride. Measurements of alumina were consistent with previously reported results. The results were used to design an insert for a high powered RF test that included sending beam through the cavity.
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WEPTY083	Five-cell Superconducting RF Module with a PBG Coupler Cell: Design and Cold Testing of the Copper Prototype	HOM, cavity, damping, impedance	3475
	S. Arsenyev, D.Y. Shchegolkov, E.I. Simakov LANL, Los Alamos, New Mexico, USA C.H. Boulware, T.L. Grimm, A. Rogacki Niowave, Inc., Lansing, Michigan, USA
	We report the design and experimental data for a copper prototype of a superconducting radio-frequency (SRF) accelerator module. The five-cell module has an incorporated photonic band gap (PBG) cell with couplers. The purpose of the PBG cell is to achieve better higher order mode (HOM) damping which is vital for preserving the quality of highcurrent electron beams. Better HOM damping raises the current threshold for beam instabilities in novel SRF accelerators. The PBG design also increases the real-estate gradient of the linac because both HOM damping and the fundamental power coupling can be done through the PBG cell instead of on the beam pipe via complicated end assemblies. First, we will discuss the design and accelerating properties of the structure. The five-cell module was optimized to provide good HOM damping while maintaining the same accelerating properties as conventional elliptical-cell modules. We will then discuss the process of tuning the structure to obtain the desired accelerating gradient profile. Finally, we will list measured quality factors for the accelerating mode and the most dangerous HOMs.
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THPF050	Applications of Beam Parameter Measurements in Transport Lines at CSNS	linac, optics, beam-transport, DTL	3815
	Z.P. Li, L. Huang, Y. Li, J. Peng, S. Wang IHEP, Beijing, People's Republic of China
	Several XAL-based applications for parameter measurements in Medium Energy Beam Transport line (MEBT) and Linac to Ring Beam Transport line (LRBT) at China Spallation Neutron Source (CSNS) have been developed. Algorithms and functions of these applications are introduced in this paper. Real Machine tests are carried out in the MEBT commissioning.
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THPF139	Nonlinear Optics of Solenoid Magnets	solenoid, focusing, lattice, optics	4048
	S.M. Lund FRIB, East Lansing, Michigan, USA
	Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 and the National Science Foundation under Grant No. PHY-1102511. Solenoid magnets are often employed for focusing in low energy beam transport lattices in the front-end of a machine. We derive a relatively simple analytic formula for the nonlinear angular focusing kick imparted to particles traversing the solenoid. Few approximations are made. The formula suggests that for beam transport, little can be done to reduce nonlinearities in solenoid-type magnets other than take a simple design without abrupt changes as a function of axial coordinate and appropriately choose the aspect ratio (characteristic bore radius over axial length) of the magnet system and the beam filling factor within the aperture to limit nonlinear effects. Illustrative applications of the formula characterize nonlinear focusing effects in iron-free and iron type solenoid magnets.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF139
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MOPWA003

Optimal Generalized Finite Difference Solution to the Particle-in-Cell Problem

framework, simulation, plasma, space-charge

77

X. Wang, X. Jiao, H. Liu, V. Samulyak, K. Yu
SBU, Stony Brook, USA
V. Samulyak
BNL, Upton, Long Island, New York, USA

The particle-in-cell (PIC) method is widely used in applications, such as in electromagnetics, but the accuracy of its solutions degrades when the particle distribution is highly non-uniform. In our work, we propose an adaptive PIC method with optimal point distribution and a generalized finite difference (GFD) scheme. Our method replaces the Cartesian grid in the classical PIC with adaptive computational nodes or particles, to which the charges from the sample particles are assigned by a weighted least-square approximations. The partial differential equation is then discretized using a GFD method and solved with fast linear solvers. The density of computational particles is chosen adaptively, so that the error from GFD and that from Monte Carlo integration are balanced and the total error is approximately minimized. We also present the verification results using electrostatic problems and comparison of accuracy and solution time of our method with the classical PIC.

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MOPWA018

Loss Factor and Impedance Analysis of Warm Components of BERLinPro

impedance, simulation, operation, wakefield

128

H.-W. Glock, M. Abo-Bakr, J. Kolbe, F. Pflocksch, A. Schälicke
HZB, Berlin, Germany
H.-W. Glock, C. Potratz
COMPAEC e.G., Rostock, Germany

Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association
The ongoing component design for the HZB 50 MeV, 100mA ERL project BERLinPro is accompanied by loss factor and impedance computations. A list of accelerator components including bellows, collimators, tapers, shutter valves etc. is given, some of them with alternative shapes. Loss factors, calculated using CSTParticleStudio®, are presented together with important properties of the impedance spectrum. Scaling of the loss factors with respect to bunch length is calculated on base of the numerical simulations and is used to extrapolate down to a bunch length (1 standard deviation) of 0.6 mm, which is hard to reach directly in numerical simulations.

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MOPWA062

Optimization of the Momentum Bandwidth for Final Focus System in CEPC

sextupole, luminosity, collider, simulation

269

S. Bai, T.J. Bian, J. Gao, H. Geng, D. Wang, Y. Wang, M. Xiao
IHEP, Beijing, People's Republic of China
F. Su
Institute of High Energy Physics (IHEP), People's Republic of China

With the discovery of the higgs boson at around 125GeV, a circular higgs factory design with high luminosity (L ~ 10³⁴ cm^-2s^-1) is becoming more popular in the accelerator world. To achieve such high luminosity, a final focus system in non-local chromaticity correction scheme with very low β functions at the interaction point is designed. The narrow momentum bandwidth is a crucial problem of this kind of design. It is shown that by introducing additional sextupoles the momentum acceptance of the CEPC final focus system can be increased by about a factor of four.

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MOPJE055

Design of an Intense Muon Source with a Carbon and Mercury Target

target, proton, collider, solenoid

423

D. Stratakis, J.S. Berg
BNL, Upton, Long Island, New York, USA
X.P. Ding
UCLA, Los Angeles, California, USA
D.V. Neuffer
Fermilab, Batavia, Illinois, USA

Funding: Authored by employees of Brookhaven Science Associates LLC under Contract DE-SC0012704 and with Fermi Research Alliance LLC under Contract DE-AC02-07CH11359 with the United States Department of Energy
In high-intensity sources, muons are produced by firing high energy protons onto a target to produce pions. The pions decay to muons which are captured and accelerated. In the present study, we examine the performance of the channel for two different target scenarios: one based on liquid mercury and another one based on a solid carbon target. We produce distributions with the two different target materials and discuss differences in particle spectrum near the sources. We then propagate the distributions through our capture system and compare the full system performance for the two target types.

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MOPJE076

Multi-objective Genetic Optimization with the General Particle Tracer (GPT) Code

solenoid, emittance, cavity, target

492

S.B. van der Geer, M.J. de Loos
Pulsar Physics, Eindhoven, The Netherlands

In a typical design process there are a large number of variables, external constraints, and multiple conflicting objectives. Examples of the latter are short pulse, high charge, low emittance and low price. The classical solution to handle such problems is to combine all objectives into one merit function. This however implicitly assumes that the tradeoffs between all objectives are a-priori known. Especially in the early design stages this is hardly ever the case. A popular solution to this problem is to switch to multi-objective genetic optimization algorithms. This class of algorithms solves the problem by genetically optimising an entire population of sample solutions. Selection and recombination operators are defined such that the output, the so-called Pareto front, only includes solutions that are fully optimized where no objective can be improved without degrading any other. Here we present numerical studies and practical test runs of the genetic optimizer built into the General Particle Tracer (GPT) code.

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MOPMA011

Evaluation of Power Supply and Alignment Tolerances for the Advanced Photons Source Upgrade

dipole, sextupole, quadrupole, power-supply

556

V. Sajaev
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.
The hybrid seven-bend-achromat lattice that has been proposed for the Advanced Photon Source upgrade will feature very strong focusing elements and will provide an electron beam with very low emittance. In order to be able to maintain stable operation, very tight tolerances are required for various types of errors. Here we describe evaluation of the effects of various errors including magnet power supplies, alignment, and vibration. Based on this analysis, we determine short- and long-term stability requirements

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MOPTY062

The Energy Saving Processes for Utility System in TPS

controls, experiment, operation, photon

1082

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

There are more and more non-linear electronic equipments such as inverters using in facility nowadays. These non-linear electronic equipments let us achieve energy saving, but induce other electrical pollution to the whole power grid in contrast. Among these electrical pollutions, electric harmonic is the most common and harmful to power facility. Therefore, how to monitor the electrical noises from these non-linear equipments becomes an important issue. In this article, a set of power quality monitoring system based on FPGA (Field-Programmable Gate Arrays) modules and PAC (Programmable Automatic Controller) has been built because of their programmability and fast processing speed. By using this monitoring system, any abnormality in power system and its spectrum will be recorded thoroughly. On the other hand, the maintainer could follow the trace of noise and then propose a suitable solution to eliminate the electrical interference too.

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TUPWA055

DAΦNE Gamma-Ray Factory

electron, laser, photon, emittance

1542

D. Alesini, S. Guiducci, C. Milardi, A. Variola, M. Zobov
INFN/LNF, Frascati (Roma), Italy
I. Chaikovska, Z.F. Zomer
LAL, Orsay, France

Gamma sources with high flux and spectral densities are the main requirements for new nuclear physics experiments to be performed in several worldwide laboratories with dedicated facilities. The presentation is focalized on a proposal of experiment of gamma photons production using Compton collisions between the DAΦNE electron beam and a high average power laser pulse, amplified in a Fabry-Pérot optical resonator. The calculations show that the resulting gamma beam source has extremely interesting properties in terms of spectral density, energy spread and gamma flux comparable (and even better) with the last generation gamma sources. The energy of the gamma beam depends on the adopted laser wavelength and can be tuned changing the energy of the electron ring. In particular we have analyzed the case of a gamma factory tunable in the 2-9 MeV range. The main parameters of this new facility are presented and the perturbation on the transverse and longitudinal electron beam dynamics is discussed. A preliminary accelerator layout to allow experiments with the gamma beam is presented with a first design of the accelerator optics.

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TUPJE017

The Generation of Highly Intense THz Radiation based on Smith-Purcell Radiation

radiation, electron, gun, cathode

1654

Y.F. Xu, Z.G. He, Q.K. Jia, W.W. Li
USTC/NSRL, Hefei, Anhui, People's Republic of China

A photocathode RF gun can generate trains of THz subpicosecond electron bunches by illuminating the cathode with trains of laser pulses. Let this electron bunches passes close to the surface of a lamellar grating, THz radiation will be emitted, which is the so-called Smith-Purcell Radiation (SPR). If the lamellar grating has a narrow groove, this radiation will be narrow-band. By choosing suitable parameter, the SPR frequency can be resonant with the electron bunches frequency, and then generate high intense, narrow band THz radiation.

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TUPTY012

Orbit Correction in CEPC

quadrupole, dipole, closed-orbit, target

2022

S. Bai, J. Gao, H. Geng
IHEP, Beijing, People's Republic of China

With the discovery of the higgs boson at around 125GeV, a circular higgs factory design with high luminosity (L ~ 10³⁴ cm^-2s^-1) is becoming more popular in the accelerator world. The CEPC project in China is one of them. To reduce the cost, pretzel scheme was considered in CEPC orbit design. The presence of every kind of errors and misalignments will destroy the pretzel orbit. In this paper, we correct the distorted pretzel orbit in the CEPC main ring using the dipole correctors and beam position monitors. The pretzel orbit was recovered and the maximum corrector strengths are got.

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TUPTY057

Scenarios for Circular Gamma-Gamma Higgs Factories

collider, laser, luminosity, electron

2156

F. Zimmermann, Y. Papaphilippou
CERN, Geneva, Switzerland
R. Aleksan
CEA/DSM/IRFU, France
A. Apyan
NU, Evanston, Illinois, USA

Funding: The research leading to these results has received partial funding from the European Commission under the FP7 Research Infrastructures project EuCARD-2, grant agreement no.312453.
The Higgs boson can be produced directly in gamma-gamma collisions generated by laser Compton back scattering off 80-90 GeV electron or positron beams. We discuss options for realizing a gamma-gamma Higgs factory using a high-energy circular e⁺e⁻ collider, such as FCC-ee or CEPC, and/or its top-up injector ring, and compare the parameters and advantages of such a facility, including the expected performance, with those for a Higgs factory based on a recirculating linac, such as SAPPHiRE.

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WEBB3

Lattice and its Related Beam Dynamics Issues in the CEPC Storage Ring

lattice, quadrupole, electron, positron

2469

H. Geng, S. Bai, Z. Duan, Y.M. Peng, Q. Qin, D. Wang, Y. Wang, G. Xu, Y. Yue, Y. Zhang
IHEP, Beijing, People's Republic of China
W. Chou
Fermilab, Batavia, Illinois, USA

The institute of High Energy Physics has proposed an electron positron collider ring with a circumference of 50-100km to study the Higgs boson. Since the proposal was made, the lattice design for CEPC has been carried out and a preliminary conceptual design report has been written at the end of 2014. In this paper, we will describe the philosophy and results of our lattice design. The procedure of dynamic aperture optimization will be shown. A specific issue for CEPC, the pretzel orbit, which has been found distorting the linear lattice for a considerable amount, will be examined. The ways that we are trying to correct the pretzel orbit effect and the result will be shown. We will also discuss the saw tooth effect on the linear lattice and dynamic aperture of the ring.

Slides WEBB3 [2.599 MB]

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WEBD2

Survey of Commissioning of Recent Storage Ring Light Sources

survey, synchrotron, vacuum, 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]

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WEPWA043

Progress on the Design of the Racetrack FFAG Decay Ring for nuSTORM

lattice, detector, closed-orbit, resonance

2594

J.-B. Lagrange, J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
R.B. Appleby, J.M. Garland, H.L. Owen, S.C. Tygier
UMAN, Manchester, United Kingdom
R.B. Appleby
Cockcroft Institute, Warrington, Cheshire, United Kingdom
Y. Mori
Kyoto University, Research Reactor Institute, Osaka, Japan

The neutrino beam produced from muons decaying in a storage ring would be an ideal tool for precise neutrino cross section measurements and search for sterile neutrinos due to its precisely known flavour content and spectrum. In the proposed nuSTORM facility pions would be directly injected into a storage ring, where circulating muon beam would be captured. The racetrack FFAG (Fixed Field Alternating Gradient) option for nuSTORM decay ring offers a very good performance due to a large dynamic and momentum acceptance. Machine parameters, linear optics design, beam dynamics and injection system for nuSTORM FFAG ring are discussed in this paper.

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WEPWA057

Design Concepts for Muon-Based Accelerators

collider, simulation, target, proton

2633

R.D. Ryne
LBNL, Berkeley, California, USA
Y.I. Alexahin, A.D. Bross, K. E. Gollwitzer, N.V. Mokhov, D.V. Neuffer, M.A. Palmer, K. Yonehara
Fermilab, Batavia, Illinois, USA
J.S. Berg, H.G. Kirk, R.B. Palmer, D. Stratakis
BNL, Upton, Long Island, New York, USA
S.A. Bogacz
JLab, Newport News, Virginia, USA
J.-P. Delahaye
SLAC, Menlo Park, California, USA
T.J. Roberts
Muons, Inc, Illinois, USA
P. Snopok
Illinois Institute of Technology, Chicago, Illinois, USA

Muon-based accelerators have the potential to enable facilities at both the Intensity and the Energy Frontiers. Muon storage rings can serve as high precision neutrino sources, and a muon collider is an ideal technology for a TeV or multi-TeV collider. Progress in muon accelerator designs has advanced steadily in recent years. In regard to 6D muon cooling, detailed and realistic designs now exist that provide more than 5 order-of-magnitude emittance reduction. Furthermore, detector performance studies indicate that with suitable pixelation and timing resolution, backgrounds in the collider detectors can be significantly reduced thus enabling high quality physics results. Thanks to these and other advances in design & simulation of muon systems, technology development, and systems demonstrations, muon storage-ring-based neutrino sources and a muon collider appear more feasible than ever before. A muon collider is now arguably among the most compelling approaches to a multi-TeV lepton collider. This paper summarizes the current status of design concepts for muon-based accelerators for neutrino factories and a muon collider.

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WEPJE010

Particle Production of a Graphite Target System for the Intensity Frontier

target, proton, emittance, collider

2692

X.P. Ding
UCLA, Los Angeles, California, USA
H.G. Kirk
BNL, Upton, Long Island, New York, USA
K.T. McDonald
PU, Princeton, New Jersey, USA

A solid graphite target system is considered for an intense muon and/or neutrino source in support of physics at the intensity frontier. We previously optimized the geometric parameters of the beam and target to maximize particle production at low energies by incoming protons with kinetic energy of 6.75 GeV and an rms geometric emittance of 5 mm-mrad using the MARS15(2014) code. In this study, we ran MARS15 with ROOT-based geometry and also considered a mercury-jet target as an upgrade operation. The optimization was extended to focused proton beams with transverse emittances from 5 to 50 mm-mrad, showing that the particle production decreases slowly with increasing emittance. We also studied the beam dump configuration to suppress the rate of undesirable higher-energy secondary particles in the beam.

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WEPMA026

Higher Order Mode Propagation and Damping Studies on Axisymmetric Superconducting Multicell RF-Resonators

cavity, damping, higher-order-mode, coupling

2812

B.D. Isbarn, B. Riemann, M. Sommer, T. Weis
DELTA, Dortmund, Germany

Funding: Work supported by the BMBF under contract no. 05K13PEB
Higher order mode (HOM) propagation and damping is a major concern in feasibility studies regarding the upcoming upgrade of BESSY II, named BESSY-VSR*, which involves the utilization of superconducting multicell RF-resonators in a storage ring while maintaining a reasonably high beam current typical for third generation synchrotron radiation facilities. In addition to the computation of the typical figures of merit, we focus on studies of the mode propagation in axisymmetric structures. Due to the focus on axisymmetric studies we are able to use 2D codes to investigate in eigenmodes with substantial higher frequencies than usually considered with full 3D codes in parametric studies. In this work we present preliminary studies involving mode propagation in superconducting elliptical multicell cavities.
* G. Wüstefeld et al., Proc. of IPAC'11, San Sebastián, THPC014

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WEPMN055

RAMI Optimization-Oriented Design For The LIPAc RF Power System

controls, rf-amplifier, target, diagnostics

3048

M. Weber, J.M. Arroyo, A. Ibarra, I. Kirpitchev, J. Mollá, P. Méndez, D. Regidor, C. de la Morena
CIEMAT, Madrid, Spain

Funding: This work has been funded by the Spanish Ministry of Economy and Competitiveness.
The Linear IFMIF Prototype Accelerator (LIPAc) is currently under construction in Rokkasho (Japan). LIPAc will generate a CW 9 MeV deuteron beam at 125 mA. It will serve to validate the final IFMIF accelerator concept and technologies. The RF power system is being integrated by CIEMAT (Spain) in collaboration with its partner companies and European institutes. LIPAc RF Power System design has been performed aiming high reliability, high availability and easy maintainability to address one of the most important requirements for IFMIF. The target of LIPAc tests is to validate the technologies and designs for the final phase of IFMIF. Several improvements in reliability, availability and maintainability have been implemented in the LIPAc RF power System. These improvements are based on both, new technologies and new maintenance philosophy. The results of their first tests are shown in this paper. Additional potential improvements are also analyzed.

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WEPHA024

Preliminary Design of a Perpendicular Biased Ferrite Loaded Accelerating Cavity

cavity, simulation, resonance, operation

3163

J. Eberhardt, F. Caspers, C. Vollinger
CERN, Geneva, Switzerland

A ferrite loaded accelerating cavity with a frequency sweep of 18 to 40 MHz is studied for a possible upgrade of the CERN accelerator complex. The resonance frequency of a ferrite loaded cavity shifts by applying an external magnetic bias field to the ferrite material by means of changing the relative permeability. We present the electromagnetic design of such a cavity with a special emphasis on the modeling of the nonlinear, anisotropic and dispersive characteristics of the ferrite’s relative permeability above magnetic saturation. For experimental crosscheck, a ferrite loaded resonant test setup was built which provides results for the material performance in a magnetic bias field. A comparison of numerical simulations and experimental measurements is shown and calculations are benchmarked by measurement data. Based on this study a preliminary design of a ferrite loaded accelerating cavity is described.

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WEPHA053

Surface Resistance RF Measurements of Materials Used for Accelerator Vacuum Chambers

cavity, coupling, resonance, network

3235

P. Goudket, L. Gurran, O.B. Malyshev, M.D. Roper, R. Valizadeh, S. Wilde
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt, L. Gurran
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
P. Goudket, O.B. Malyshev, R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom
S. Wilde
Loughborough University, Loughborough, Leicestershire, United Kingdom

The RF surface resistance of accelerator vacuum chamber walls can have a significant impact on the beam quality. There is a need to know how the use of a new material, surface coating or surface treatment can affect the RF surface resistance. ASTeC and Lancaster University have designed and built two test cavities where one face can be replaced with a sample in the form of a flat plate. The measurements are performed with a network analyser at the resonant frequency of approximately 7.8 GHz.

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WEPTY034

T-map Studies on Gradient-limiting Mechanism in Nitrogen Doped Cavities

cavity, niobium, superconductivity, SRF

3348

M. Martinello, M. Checchin, A. Grassellino, A. Romanenko
Fermilab, Batavia, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Nitrogen doping * results in ultra-high quality factors in SRF niobium cavities but currently achievable gradients in doped cavities are, on average, somewhat lower than in EP/120C baked cavities. The origin of this difference is explored in the reported work by detailed temperature mapping studies on several single cell nitrogen doped cavities.
* A. Grassellino et al, 2013 Supercond. Sci. Technol. 26 102001

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WEPTY050

Low Powered RF Measurements of Dielectric Materials for use in High Pressure Gas Filled RF Cavities

cavity, simulation, radio-frequency, collider

3387

B.T. Freemire
IIT, Chicago, Illinois, USA
G. Arriaga
Northern Illinois Univerity, Dekalb, Illinois, USA
D.L. Bowring, A.V. Kochemirovskiy, A. Moretti, A.V. Tollestrup, Y. Torun, K. Yonehara
Fermilab, Batavia, Illinois, USA
H.D. Phan
McDaniel College, Westminster, USA
Y. Torun
Illinois Institute of Technology, Chicago, Illlinois, USA

The Helical Cooling Channel scheme envisioned for a Muon Collider or Neutrino Factory requires high pressure gas filled radio frequency cavities to operate in superconducting magnets. One method to shrink the radii of the cavities is to load them with a dielectric material. The dielectric constant, loss tangent, and dielectric strength are important in determining the most suitable material. Low powered RF measurements of the dielectric constant and loss tangent were taken for multiple purities of alumina and magnesium calcium titanate, as well as cordierite, forsterite, and aluminum nitride. Measurements of alumina were consistent with previously reported results. The results were used to design an insert for a high powered RF test that included sending beam through the cavity.

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WEPTY083

Five-cell Superconducting RF Module with a PBG Coupler Cell: Design and Cold Testing of the Copper Prototype

HOM, cavity, damping, impedance

3475

S. Arsenyev, D.Y. Shchegolkov, E.I. Simakov
LANL, Los Alamos, New Mexico, USA
C.H. Boulware, T.L. Grimm, A. Rogacki
Niowave, Inc., Lansing, Michigan, USA

We report the design and experimental data for a copper prototype of a superconducting radio-frequency (SRF) accelerator module. The five-cell module has an incorporated photonic band gap (PBG) cell with couplers. The purpose of the PBG cell is to achieve better higher order mode (HOM) damping which is vital for preserving the quality of highcurrent electron beams. Better HOM damping raises the current threshold for beam instabilities in novel SRF accelerators. The PBG design also increases the real-estate gradient of the linac because both HOM damping and the fundamental power coupling can be done through the PBG cell instead of on the beam pipe via complicated end assemblies. First, we will discuss the design and accelerating properties of the structure. The five-cell module was optimized to provide good HOM damping while maintaining the same accelerating properties as conventional elliptical-cell modules. We will then discuss the process of tuning the structure to obtain the desired accelerating gradient profile. Finally, we will list measured quality factors for the accelerating mode and the most dangerous HOMs.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY083

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THPF050

Applications of Beam Parameter Measurements in Transport Lines at CSNS

linac, optics, beam-transport, DTL

3815

Z.P. Li, L. Huang, Y. Li, J. Peng, S. Wang
IHEP, Beijing, People's Republic of China

Several XAL-based applications for parameter measurements in Medium Energy Beam Transport line (MEBT) and Linac to Ring Beam Transport line (LRBT) at China Spallation Neutron Source (CSNS) have been developed. Algorithms and functions of these applications are introduced in this paper. Real Machine tests are carried out in the MEBT commissioning.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF050

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THPF139

Nonlinear Optics of Solenoid Magnets

solenoid, focusing, lattice, optics

4048

S.M. Lund
FRIB, East Lansing, Michigan, USA

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 and the National Science Foundation under Grant No. PHY-1102511.
Solenoid magnets are often employed for focusing in low energy beam transport lattices in the front-end of a machine. We derive a relatively simple analytic formula for the nonlinear angular focusing kick imparted to particles traversing the solenoid. Few approximations are made. The formula suggests that for beam transport, little can be done to reduce nonlinearities in solenoid-type magnets other than take a simple design without abrupt changes as a function of axial coordinate and appropriately choose the aspect ratio (characteristic bore radius over axial length) of the magnet system and the beam filling factor within the aperture to limit nonlinear effects. Illustrative applications of the formula characterize nonlinear focusing effects in iron-free and iron type solenoid magnets.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF139

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