IPAC2018 - List of Keywords (site)

Paper	Title	Other Keywords	Page
MOZGBE4	Overview of Fabrication Techniques and Lessons Learned with Accelerator Vacuum Windows	vacuum, Windows, target, operation	51
	C.R. Ader, M.W. McGee, L.E. Nobrega, E.A. Voirin Fermilab, Batavia, Illinois, USA
	Funding: Operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02- 07CH11359 with the U.S. Department of Energy. Vacuum thin windows have been used in Fermilab's accelerators for decades and typically have been overlooked in terms of their criticality and fragility. Vacuum windows allow beam to pass through while creating a boundary between vacuum and air or high vacuum and low vacuum areas. The design of vacuum windows, including titanium and beryllium windows, will be discussed as well as fabrication, testing, and operational concerns. Failure of windows will be reviewed as well as safety approaches to mitigating failures and extending the lifetimes of vacuum windows. Various methods of calculating the strengths of vacuum windows will be explored, including FEA.
	Slides MOZGBE4 [2.155 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBE4
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MOPMF021	Ground Motion Measurement and Analysis for HEPS	ground-motion, emittance, ion-source, lattice	125
	F. Yan, Z. Duan, D. Ji, Y. Jiao, Z.Z. Wang, Y. Wei, G. Xu IHEP, Beijing, People's Republic of China
	HEPS have very challenging beam stability require-ments. Special cares are mandatory in developing site vibration specifications, stable building design concepts, and passive and active ways to minimize effects on the stability of the photon beam and critical accelerator and beamline components caused by ambient ground motion sources. However, among all these work, reasonable as-sessment of the vibration induced beam instability has to be the first step. This paper will focuses on the measure-ment results of the ground motion on HEPS site, the es-tablishment of reasonable beam dynamic models, the influences of ground motion to the beam of main ring.
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MOPML053	Mu*STAR Accelerator-Driven Subcritical Reactors Burning Spent Nuclear Fuel at Light-Water-Reactor Sites	target, neutron, operation, SRF	524
	R.P. Johnson, R.J. Abrams, M.A. Cummings, T.J. Roberts Muons, Inc, Illinois, USA
	This project will use modeling and simulation tools to optimize many aspects of the MuSTAR design and begin to explore accident scenarios. At present we have a conceptual design of the accelerator, the reactor, the spallation target, and the fractional distillation to separate volatile fission products. Our GAIN project with ORNL is preparing a design of the Fuel Processing Plant that will convert spent nuclear fuel into the molten-salt fuel for MuSTAR. This includes all of the nuclear components, but not such things as the turbine and generator, physical plant, control and monitoring systems, etc. We currently have basic simulations of the reactor neutronics, and a start at calculating the fuel evolution. These have used MCNP and ORIGEN, and initial results have been reported1. This project will support the use of additional neutronics and multi-physics codes, enabling a much more thorough analysis of the system.
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MOPML070	Thermal and Stress Analysis of an X-Ray Target for 6 MeV Medical Linear Accelerators	target, electron, simulation, photon	572
	Z.H. Wang, H.B. Chen, J. Shi, H. Zha TUB, Beijing, People's Republic of China
	We present an optimal design of an X-ray target for 6 MeV medical linear accelerators using FLUKA simula-tions. The target is composed of high-atomic number tungsten and high-thermal conductivity copper, corre-sponding water-cooling system is showed too. Further-more, we analyse the temperature and thermal stress re-sponses of the target under transient thermal loads using Ansys Code. For 6 MeV electron beam with 100 uA cur-rent, the results show that the target can achieve 1014 cGy/min at 1meter in front of the target. Within 100 ms, the maximum temperature reaches 512 °C under pulsed heating source with 250 Hz frequency and 1' duty cycle and the number of cycles to failure is estimated as 5.8·10⁸.
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TUPAF044	Schedule Evolution of the Linac4 Installation During the Lifetime of the Linac4 Project and Connection Forecast	linac, civil-engineering, MMI, status	794
	J. Coupard, A. Berjillos, J.-P. Corso, K. Foraz, B. Nicquevert, E. Paulat, M. Vretenar CERN, Geneva, Switzerland
	The new CERN linear accelerator Linac4 started the installation phase in 2010 after the delivery of the new building and tunnel by the civil engineering and was inaugurated six years later. It will be connected to the CERN accelerators chain and replace the current proton linear accelerator, Linac2, during the second long shut-down (LS2) of the Large Hadron Collider (LHC) in 2019. This paper aims to summarize the schedule evolution through the different phases of installation, from general services to machine installation, highlight the key factors that contributed to drive the schedule (safety, logistics and integration) and describe the coordination study of the future connection (integration, schedule, logistics, constraints and priorities).
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TUPAF064	Preparation Towards the Ess Linac Ion Source and Lebt Beam Commissioning on Ess Site	MMI, rfq, linac, solenoid	874
	R. Miyamoto, M. Eshraqi, A. Jansson, E. Laface, Y. Levinsen, O. Midttun, N. Milas, M. Muñoz, D.C. Plostinar, A. Ponton, E. Sargsyan, L. Tchelidze ESS, Lund, Sweden L. Celona, L. Neri INFN/LNS, Catania, Italy W. Ledda Vitrociset s.p.a, Roma, Italy
	Beam commissioning of the proton linac of the European Spallation Source begin in summer, 2018, from the ion source (IS) and low energy beam transport (LEBT), and continues in stages until 2022, when the first beam is sent to its spallation target. This paper presents the plan, status, and highlights of preparation works for the upcoming IS and LEBT beam commissioning.
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TUPAF075	Design Status of the LBNF/DUNE Beamline	target, proton, shielding, status	902
	V. Papadimitriou, J.E. Anderson, R. Andrews, J.J. Angelo, V.T. Bocean, C.F. Crowley, A. Deshpande, N. Eddy, K. E. Gollwitzer, S. Hays, P. Hurh, J. Hylen, J.A. Johnstone, P.H. Kasper, T.R. Kobilarcik, G.E. Krafczyk, N.V. Mokhov, D. Pushka, S.D. Reitzner, P. Schlabach, V.I. Sidorov, M. Slabaugh, S. Tariq, L.R. Valerio, K. Vaziri, G. Velev, G.L. Vogel, K.E. Williams, R.M. Zwaska Fermilab, Batavia, Illinois, USA C.J. Densham STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
	Funding: DOE, contract No. DE-AC02-07CH11359 The Long Baseline Neutrino Facility (LBNF) will utilize a beamline located at Fermilab to provide and aim a wide band beam of neutrinos of sufficient intensity and appropriate energy toward DUNE detectors, placed 4850 feet underground at SURF in South Dakota, about 1,300 km away. The primary proton beam (60-120 GeV) will be extracted from the MI-10 section of Fermilab's Main Injector. Neutrinos are produced after the protons hit a four-interaction length solid target and produce mesons which are subsequently focused by a set of three magnetic horns into a 194 m long helium filled decay pipe where they decay into muons and neutrinos. The parameters of the facility were determined taking into account the physics goals, spatial and radiological constraints, extensive simulations and the experience gained by operating the NuMI facility at Fermilab. The Beamline facility is designed for initial operation at a proton-beam power of 1.2 MW, with the capability to support an upgrade to about 2.4 MW. LBNF/DUNE obtained CD-1 approval in November 2015 and CD-3a approval in September 2016. We discuss here the Beamline design status and the associated challenges.
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TUPAF083	SIS100 Tunnel Design and Civil Construction Status	status, radiation, experiment, shielding	927
	C. Omet, J. Falenski, H. Kisker, K. Konradt, P.J. Spiller GSI, Darmstadt, Germany A. Fischer FAIR, Darmstadt, Germany
	As the FAIR Project is proceeding, building designs have been frozen and the according work packages tendered. For the future FAIR main driver accelerator, SIS100, the 1.1 km long accelerator tunnel "T110", has been planned 17 m deep under ground. In this article, environmental boundary conditions, the chosen layout and the current status of civil construction is presented.
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TUPAF084	The First-of-Series SIS100 Cryocatcher	vacuum, cryogenics, HOM, instrumentation	930
	L.H.J. Bozyk, Sh. Ahmed, P.J. Spiller GSI, Darmstadt, Germany
	The superconducting heavy ion synchrotron SIS100 of the FAIR-facility will be equipped with 60 cryocatcher, to suppress dynamic vacuum effects. A prototype cryocatcher has been designed, manufactured and underwent several tests. The results yielded in the design of the series cryocatcher. Recently, the First-of-Series cryocatcher has been manufactured and tested. Results from the manufacturing process and the site acceptance tests, including cryogenic test with liquid helium are presented. The FoS cryocatcher sucessfully passed all tests and the series production will be released.
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TUPAL012	Design and Fabrication of Hybrid RFQ Prototype	DTL, rfq, linac, cavity	1032
	P.Y. Yu, Y. He, C.X. Li, G.Z. Sun, F.F. Wang, Z.J. Wang, B. Zhang, T.M. Zhu IMP/CAS, Lanzhou, People's Republic of China
	Hybrid RFQ is proposed as a potential good choice at the low-energy range of linear accelerator. The complexi-ty of mechanical design and difficulty of fabrication are part of reasons impeding application of it and similar structures. In order to explore the practicable structure and research on RF parameters of this accelerating struc-ture, an aluminium prototype is developed.
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TUPAL057	Preliminary Experiments in Caesium Delivery and Gettering on the ISIS Vespa Source	experiment, ion-source, plasma, operation	1144
	T. M. Sarmento, R.E. Abel, D.C. Faircloth, S.R. Lawrie, J.H. Macgregor, M. Whitehead, T. Wood STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	Caesium capture by graphite at various temperatures 20- 300°C in the VESPA ion source test stand was explored in a preliminary experiment. An accompanying experiment was set up to evaluate the control of caesium boiler delivery in the various ISIS penning sources. Results indicate Cs flux fluctuates at constant settings, which must be accounted for to interpret graphite gettering results. Future studies to identify the cause of fluctuations are considered, and a more rigorous experiment to study the use of graphite is introduced.
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WEPAF018	Proposed BPM-Based Bunch Crabbing Angle Monitor	cavity, simulation, electron, diagnostics	1860
	P. Thieberger, M.G. Minty, C. Montag BNL, Upton, Long Island, New York, USA
	Funding: This work was supported by Brookhaven Science Associates, LLC, under Contract No. DE-AC02-98CH10886 with the US Department of Energy. A tilted bunch traversing a button beam profile monitor will produce signals on opposite pickup electrodes that will have different degrees of distortion depending on the tilt angle. In particular, the zero-crossing time difference between the two signals will be approximately proportional to the tilt angle. We perform simulations to study this effect as a possible diagnostic tool for measuring the crabbing angles in a future electron-ion collider.
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WEPAL049	Simulating Non-Relativistic Beams Using Helical Pulse Lines	impedance, simulation, ECR, GUI	2288
	C.J. Richard NSCL, East Lansing, Michigan, USA S.M. Lidia FRIB, East Lansing, USA
	Funding: Work supported by the US Department of Energy, Office of Science, High Energy Physics under Cooperative Agreement award number DE-SC0018362. Benchtop calibration of capacitive beam position monitors (BPMs) in low energy beamlines is challenging due to non-relativistic effects. Typical benchtop calibrations cannot account for these effects because they rely on speed of light fields transmitted along a straight wire. However, it is possible to replicate the electromagnetic fields generated by non-relativistic beams using a helical line pulse instead of a straight wire. In order to properly replicate the fields from a beam, a method must be developed for tailoring input pulses into the helical line to match bunch shape and a model of the impedance of the helix should be developed to assist with matching. This paper uses the sheath helix model to analyze signal propagation along a helical line in the time domain, with attention to dispersive effects and impedance matching. The results from this model are then compared to Microwave Studio simulations.
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WEPAL059	Observation and Suppression of Beam Orbit Drift Due to Path Length Changes and Thermal Effect in TPS	feedback, controls, operation, electron	2313
	P.C. Chiu, K.T. Hsu, K.H. Hu, C.H. Huang, C.-C. Kuo NSRRC, Hsinchu, Taiwan
	Tidal effect, ambient temperature fluctuation and other effects of the TPS site can cause the path length changes of the electron beam in the TPS storage ring. Off-energy orbit drifts from the path length change, if not varying the RF frequency, cannot be properly corrected by the horizontal correctors and this causes the fast orbit feedback system over its normal working range. RF frequency adjustment loop is therefore applied to compensate for the circumference change based on the accumulating corrector strengths of the fast orbit feedback system. Implementation and operational experiences will be discussed in the report.
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WEPAL075	Time-Resolved Transverse Beam Profile Measurements with a Rest Gas Ionisation Profile Monitor Based on Hybrid Pixel Detectors	electron, detector, background, proton	2361
	S. Levasseur, S.M. Gibson Royal Holloway, University of London, Surrey, United Kingdom W. Bertsche, H. Sandberg UMAN, Manchester, United Kingdom D. Bodart, A. Huschauer, G. Schneider, J.W. Storey, R. Veness CERN, Geneva, Switzerland M. Sapinski GSI, Darmstadt, Germany K. Satou J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	A novel rest gas ionisation profile monitor which aims to provide continuous, bunch-by-bunch and turn-by-turn measurement of the transverse beam profile has recently been in- stalled in the CERN Proton Synchrotron (PS) as part of the LHC Injector Upgrade (LIU) project. The instrument consists of an electric drift field to transport ionisation electrons produced by beam-gas interaction onto a measurement plane, and a magnetic field to maintain the transverse position of the ionisation electrons. The electron detector located at the measurement plane is based on four in-vacuum hybrid pixel detectors. The detectors record the position, time and energy of single ionisation electrons with unprecedented precision compared to traditional MCP based techniques. Continuous transverse beam profile measurements for LHC-type beams in the PS will be presented, demonstrating the unique capabilities of the instrument to provide new insights into beam dynamics throughout the acceleration cycle.
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WEPMF014	Fast Track Actively Shielded Nb3Sn IR Quadrupole R&D	quadrupole, hadron, collider, coupling	2398
	B. Parker, M. Anerella, J.P. Cozzolino, R.C. Gupta, R.B. Palmer, J. Schmalzle, H. Witte BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. The Interaction Region (IR) magnets for future Electron Ion Colliders (EIC), such as eRHIC at BNL, JLEIC at JLab and LHeC at CERN, must satisfy strongly opposing requirements. EIC IR superconducting quadrupole coils must provide strong focusing gradients, leading to large peak fields, for the high momentum hadron beam while permitting the nearby electron beam to pass through a nearly field free region. An actively shielded coil geometry does this using nested, opposite polarity, quadrupoles where the combined external fields cancel while leaving a net gradient inside. In order to fabricate and test this concept in a timely and cost effective manner we propose to reuse the inner coils from an existing high gradient Nb3Sn LARP quadrupole inside a new structure with a new NbTi active shield coil. The main challenge is to design a compact structure for applying prestress to the Nb3Sn coil that fits the restricted space inside the shield coil. We first construct a 15 cm long mechanical model of this structure with coil strain gauges to verify the design concept before proceeding with the full coil. Mechanical modeling results and our preliminary design concept are reported here.
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WEPMF047	Performance of Samples With Novel SRF Materials and Growth Techniques	cavity, SRF, superconducting-RF, niobium	2475
	T.E. Oseroff, M. Ge, M. Liepe, J.T. Maniscalco, R.D. Porter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA S.R. McNeal Ultramet, Pacoima, California, USA M.J. Sowa Veeco-CNT, Medford, USA
	Novel materials are currently being studied in an attempt to push accelerating superconducting RF cavities to support higher accelerating fields and to operate with lower power loss. Growing layers of these materials of the quality necessary has proven to be difficult. In this work, we present the SRF performance of planar samples of the promising materials, NbN and Nb¬3Sn, grown using atomic layer deposition (ALD) and chemical vapor deposition (CVD) respectively. Results are promising.
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WEPMF050	Update on Nb3Sn Progress at Cornell University	cavity, niobium, SRF, accelerating-gradient	2479
	R.D. Porter, J. Ding, D.L. Hall, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA T.A. Arias, P. Cueva, D.A. Muller, N. Sitaraman Cornell University, Ithaca, New York, USA
	Niobium-3 Tin (Nb3Sn) is the most promising alternative material for SRF accelerator cavities. The material can achieve higher quality factors, higher temperature operation and potentially higher accelerating gradients compared to conventional niobium. Cornell University has a leading program to produce 2 - 3 micrometer thick coatings of Nb3Sn on Nb for SRF applications using vapor diffusion. This program has been the first to produce quality factors higher than achievable with conventional Nb at usable accelerating gradients. Here we present an update on progress at Cornell University, including studies of the formation of the Nb3Sn layer, density functional theory calculations of Nb3Sn growth, and designs for a sample host cavity for measuring the quench field of Nb3Sn.
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WEPMF071	Dynamic Testing and Characterization of Advanced Materials in a New Experiment at CERN HiRadMat Facility	experiment, target, damping, proton	2534
	A. Bertarelli, C. Accettura, E. Berthomé, L. Bianchi, F. Carra, C. Fichera, M.I. Frankl, G. Gobbi, P. Grosclaude, M. Guinchard, A. Lechner, M. Pasquali, S. Redaelli, E. Rigutto, O. Sacristan De Frutos CERN, Geneva, Switzerland Ph. Bolz, P. Simon GSI, Darmstadt, Germany T.R. Furness University of Huddersfield, Huddersfield, United Kingdom J. Guardia Valenzuela Universidad de Zaragoza, Zaragoza, Spain P. Mollicone, M. Portelli UoM, Msida, Malta
	Funding: This work has received funding from the European Union's Horizon 2020 Research and Innovation programme under Grant Agreement No 730871. An innovative and comprehensive experiment (named "Multimat") was successfully carried out at CERN HiRadMat facility on 18 different materials relevant for Collimators and Beam Intercepting Devices. Material samples, tested under high intensity proton pulses of 440 GeV/c, exceeding the energy density expected in HL-LHC, ranged from very light carbon foams to tungsten heavy alloys, including novel composites as graphite/carbides and metal/diamond without and with thin-film coatings. Experimental data were acquired relying on extensive integrated instrumentation (strain gauges, temperature sensors, radiation-hard camera) and on laser Doppler vibrometer. This allows investigating relatively unexplored and fundamental phenomena as dynamic strength, internal energy dispersion, nonlinearities due to inelasticity and inhomogeneity, strength and delamination of coatings and surfaces. By benchmarking sophisticated numerical simulations against these results, it is possible to establish or update material constitutive models, which are of paramount importance for the design of devices exposed to interaction with particle beams in high energy accelerators such as the HL-LHC or FCC-hh.
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WEPML025	Advantages and Challenges of Nb3Sn Superconducting Undulators	undulator, experiment, operation, photon	2734
	A.V. Zlobin, E.Z. Barzi, D. Turrioni Fermilab, Batavia, Illinois, USA Y. Ivanyushenkov, I. Kesgin ANL, Argonne, Illinois, USA
	Funding: This work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. Superconducting undulators (SCUs) employ superconducting coils, and due to high critical current density in a superconductor, outperform undulators based on permanent magnets in terms of the level of magnetic field. So far, most of the SCUs, including devices built at Advanced Photon Source (APS), use Nb-Ti superconductor. Utilization of Nb3Sn conductor offers a possibility to increase the undulator field even further but requires to overcome certain challenges that are described in this paper. Based on experience of developing Nb3Sn accelerator magnets at Fermi National Accelerator Laboratory, possible solutions are discussed. The achievable field levels for Nb3Sn version of existing APS and the future APS-Upgrade superconducting undulators are also presented and discussed.
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WEPML067	Second Sound Quench Detection on Superconducting Cavities	cavity, detector, SRF, superconducting-cavity	2843
	Z.C. Liu, S. Bai, J. Gao, F.S. He, H.Y. Lin, P. Zhang IHEP, Beijing, People's Republic of China
	Second sound is an effective way to detect the quench position on superconducting cavity. A second sound quench site detection system is under developing for the PAPS. High gradient is very important for superconducting cavity, however it may be limited by quench on the cavity high field region. Quench can be caused by various reasons. To locate the position is the key to reveal the mysteries of quench. Now we are developing the quench position detection system by RTD sensors such as Cernox and OST sensors.
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WEPML075	Test of Magnet Girder Prototypes for HEPS-TF	alignment, coupling, HOM, photon	2863
	H. Wang, C. H. Li, S.J. Li, J. Liu, H. Qu, Z. Wang, L. Wu IHEP, Beijing, People's Republic of China H.Y. Zhu Institute of High Energy Physics (IHEP), People's Republic of China
	Auto-tuning magnet girder is one of the key technolo-gies to be solved for HEPS-TF (Test Facility of High Ener-gy Photon Source). The girder should have high adjusting accuracy, high stability and can be beam-based aligned, to obtain the stability requirements of beam orbit. There are two girders developed, and the tests have been done. The accuracy of girder motion is within 10 microns while the adjusting range is 1 mm and the resolution is better than 1 microns, the natural frequency is higher than 24 Hz.
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THPAF026	Modeling Studies for Synchrotron-Radiation-Induced Electron Production in the Vacuum Chamber Walls at CesrTA	photon, electron, simulation, vacuum	3011
	S. Poprocki, J.A. Crittenden, D. L. Rubin, D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467 and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505. We report on calculations of electron production by synchrotron radiation absorbed in the vacuum chamber walls of the Cornell Electron Storage Ring (CESR). These electrons are the source of electron clouds which limit the performance of storage rings by causing betatron tune shifts, instabilities and emittance growth. Until now, cloud buildup modeling codes have used ad hoc models of the production of the seed electrons. We have employed the photon scattering code Synrad3D to quantify the pattern of absorbed photons around the CESR ring, including the transverse distribution on the wall of the beam-pipe. These distributions in absorbed photon energy and incident angle are used as input to Geant4-based simulations of electron emission from the walls. The average quantum efficiency is found to vary dramatically with the location of the absorption site, owing to the distribution in impact energies and angles. The electron production energy spectrum plays an important role in the modeling of electron cloud buildup, where the interplay of production energy and acceleration by the beam bunches determines the time structure and multipacting characteristics of the cloud.
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THPAF047	Measurements and Impact of Stray Fields on the 380 GeV Design of CLIC	emittance, dipole, collider, background	3072
	C.G. Gohil, M.C.L. Buzio, E. Marín, D. Schulte CERN, Geneva, Switzerland P. Burrows JAI, Oxford, United Kingdom
	Previous studies of the 3 TeV Compact Linear Collider (CLIC) design have shown a sensitivity to external dynamic magnetic fields (stray fields) on the nanoTesla level. In this paper the obtained tolerances for stray fields in the 380 GeV CLIC design are presented. In order to determine potential stray field sources, a measurement sensor has been acquired and used to investigate the magnetic contamination from technical equipment. The collected measurements, as well as details of the sensor, are discussed.
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THPAL031	Development of a Vertical Electropolishing Facility for Nb 9-Cell Cavity	cavity, niobium, cathode, controls	3699
	Y.I. Ida, V. Chouhan, K.N. Nii MGH, Hyogo-ken, Japan akabori. Akabori, G.M. Mitoya, K. Miyano HKK, Morioka, Japan Y. Anetai, F. Takahashi WING. Co.Ltd, Iwate-ken, Japan H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe KEK, Ibaraki, Japan
	Our Nb accelerating cavity vertical electropolishing (VEP) facility development group which was led by KEK started single-cell VEP facility development from 2014. This is based on horizontal electropolishing (HEP) techniques developed by KEK over 10 years and stainless steel electropolishing techniques developed by Marui over 30 years. We have reported results of Nb cavity VEP with Ninja cathode so far. In order to achieve international linear collider (ILC) construction, it is said that cost reduction and productivity improvement are necessary, however in case of 9-cell cavity, uniform inner surface polishing is difficult, as well known to predecessors. In this article, we will present the first report of VEP facility development from initial transparent plastic mock-up to improvement for Nb 9-cell cavity.
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THPAL036	Nb3Sn Thin Films for the Production of Higher Gradient SRF Cavities at Reduced Cost	cavity, niobium, SRF, superconductivity	3716
	S.A. Kahn, M.A. Cummings Muons, Inc, Illinois, USA E.Z. Barzi, D. Turrioni Fermilab, Batavia, Illinois, USA S. Falletta Politecnico di Torino, Torino, Italy A. Kikuchi NIMS, Tsukuba, Ibaraki, Japan
	High gradient superconducting cavities (SRF) will be needed for future accelerators. The higher gradient can achieve the high energy with fewer cavities. However the accelerating field of niobium cavities is limited by the peak magnetic field on the cavity surface. Cavities coated with Nb3Sn have a significantly larger Hc2 allowing the cavity to achieve a larger gradient. Measurements of Nb3Sn coated cavities have achieved about half the theoretical predicted gradient. It is possible to improve Nb3Sn plated cavity performance.
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THPAL040	Lossy Beam Pipe HOM Load Ceramics with DC Conductivity	experiment, vacuum, HOM, controls	3729
	M.L. Neubauer, A. Dudas Muons, Inc, Illinois, USA F. Marhauser JLab, Newport News, Virginia, USA
	The ceramic materials used in the beam pipe for super-conducting RF accelerators have the problem of charging due to the electron cloud and secondary electron emission. A novel solution is in the application of conductive nanoparticles to the lossy ceramic. The lossy ceramic is pre-processed to provide for pores that will accept the conductive nanoparticles and then coated with a thin film to prevent the nanoparticles from entering the environment. The same process was also done with sub-micron carbon particles. Measurements of surface conductivity with and without a vacuum compatible sealant are reported on along with microwave measurements.
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THPAL042	Injection Locked 1497 MHz Magnetron	injection, superconducting-cavity, cavity, medical-accelerators	3736
	M.L. Neubauer, A. Dudas, S.A. Kahn Muons, Inc, Illinois, USA R.A. Rimmer, H. Wang JLab, Newport News, Virginia, USA
	A novel injection-locked 1497 MHz 13 kW AM magnetron design is presented. The anode design to minimized eddy currents due to the changing magnetic field is presented. Thermal calculations of two design options are also presented. An extra degree of freedom in the anode construction is made possible by the fact that the magnetron is injection locked. This fact presents some additional design details that can be utilized in the cooling network for the magnetron anode.
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THPAL050	Beam Dynamics of the First Beams for the IFMIF-EVEDA RFQ Commissioning	operation, controls, storage-ring, synchrotron	3754
	C.S. Chen, W.S. Chan, Y.Y. Cheng, Y.-C. Chung, C.Y. Liu, Y.-H. Liu, Z.-D. Tsai NSRRC, Hsinchu, Taiwan
	Since December 31th 2014, the first synchrotron light from Taiwan Photon Source (TPS) was stored in the storage ring, the challenge to operate both Taiwan Light Source (TLS) and TPS smoothly and reliably became a significant issue for all members in NSRRC. On the one hand, the beam quality of former TLS must not been impaired due to the occupied resources by TPS, on the other hand, the most efforts were devoted to achieving steady operation of TPS. In order to operate both ring stably, some mutual backup structures were designed in the compressed air system and the chilled water system between TLS and TPS. The primary advantage of these mutual backup systems is minimizing the risk of beam-trip while any one of the utility system fails. Secondly, the mutual backup structures provide more flexible usage to accomplish energy conservation. From both risk-reduction and energy conservation points of view, the backup systems will do a great deal of good in the future.
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THPAL059	TEMPERATURE ISSUES OF THE TPS BPMS	impedance, wakefield, simulation, resonance	3781
	Y.T. Huang, C.-C. Chang, C.M. Cheng, P.J. Chou, Y.C. Yang NSRRC, Hsinchu, Taiwan
	Since the TPS is capable to operate at higher currents, long-term 400mA conditioning runs were conducted. Current-dependent temperature data of BPMs were collected and analysed for both, aluminium and stainless steel BPM chambers. To better understand beam coupling effects in different types of TPS BPMs, electromagnetic and thermal simulation models were established. In this paper, we discuss associated results of such studies.
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THPAL089	Design, Assembly and Commissioning of a New Cryogenic Facility for Complex Superconducting Thin Film Testing	SRF, experiment, cavity, operation	3859
	O.B. Malyshev, L. Bizel-Bizellot, K.D. Dumbell, P. Goudket, N. Pattalwar, S.M. Pattalwar, P. Pizzol, P.A. Smith, R. Valizadeh, S. Wilde STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom P. Pizzol The University of Liverpool, Liverpool, United Kingdom
	An ongoing study on the superconducting thin films for future superconducting RF cavities requires an intense testing of various superconducting properties. We have designed, built and tested a new facility for complex superconducting thin film testing that includes: (1) RRR measurement with and without magnetic field, (2) planar and (3) tubular magnetic field penetration experiments, (4) a superconducting coaxial resonator for bulk niobium and superconducting thin film characterisation. The system is based on a closed cycle refrigerator, eliminating the need for liquid helium, thus making it simple and safe to operate. The details of the design and commissioning will be presented at the conference.
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THPAL098	Pumping Properties of Single Metal Zirconium Non-Evaporable Getter Coating	vacuum, target, experiment, injection	3869
	Sirvinskaite, R. Sirvinskaite, M.D. Cropper, M.D. Cropper Loughborough University, Loughborough, Leicestershire, United Kingdom A.N. Hannah, O.B. Malyshev, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom O.B. Malyshev, R. Valizadeh Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Non-evaporable getter (NEG) coating has been used for years in many particle accelerator facilities due to its evenly distributed pumping speed, low thermal outgassing, and low photon and electron stimulated desorption yields. We have previously demonstrated that quaternary Ti-Zr-Hf-V coating deposited from an alloy wire has the lowest desorption yields, the highest sticking probability and sorption capacity. In this work, we explore the single element targets which are widely available and can be produced in a form of a wire that is easy to apply for a uniform coating of various shapes of vacuum chamber. Single metal Zr coatings have been tested to find a more efficient and cheaper way of producing the NEG-coated vacuum chambers. Two samples coated with Zr of dense and columnar structure were analysed and results of the pumping properties are reported. The results show that pure Zr coating could be an economic solution, despite not being as effective as can be achieved with quaternary NEG film. It shows that columnar Zr coating can be activated and reaches full pumping capacity at 160°C. This is close to the activation temperature of Ti-Zr-Hf-V and lower than that for the widely used ternary Ti-Zr-V alloy.
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THPAL129	Magnetron Sputtering of Nb3Sn for SRF Cavities	cavity, SRF, target, controls	3946
	MNS. Sayeed, H. Elsayed-Ali ODU, Norfolk, Virginia, USA G.V. Eremeev, M.J. Kelley, C.E. Reece JLab, Newport News, Virginia, USA M.J. Kelley, U. Pudasaini The College of William and Mary, Williamsburg, Virginia, USA M.J. Kelley Virginia Polytechnic Institute and State University, Blacksburg, USA
	Nb3Sn is a potential candidate for surface material of SRF cavities since it can enable the cavity to operate at higher temperatures with high quality factor and at an increased accelerating gradient. Nb-Sn films were deposited using magnetron sputtering of individual Nb and Sn targets onto Nb and sapphire substrates. The as-deposited films were annealed at 1200 °C for 3 hours. The films were characterized for their structure by X-ray Diffraction (XRD), morphology by Field Emission Scanning Electron Microscopy (FESEM), and composition by Energy Dispersive X-ray Spectroscopy (EDS) and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The surface resistivity was measured down to cryogenic temperature to determine the superconducting transition temperature and its width. The composition of the multilayered films was controlled by varying the thickness of the Nb and Sn layers. The films showed crystalline Nb3Sn phases with Tc up to 17.6 K.
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THPAL140	Rework Recipe Development, Analysis and Results of Select 9-Cell Cavities for LCLS-II	cavity, embedded, niobium, linac	3968
	A.D. Palczewski, K. Macha, H. Park, C.E. Reece, K.M. Wilson JLab, Newport News, Virginia, USA A. Burrill, D. Gonnella SLAC, Menlo Park, California, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The SLAC National Accelerator Laboratory is currently constructing a major upgrade to its accelerator, the Linac Coherent Light Source II (LCLS-II). Several Department of Energy laboratories, including the Thomas Jefferson National Accelerator Facility (JLab) and Fermi National Accelerator Laboratory (FNAL), are collaborating in this project. The cryomodules for this project each consist of eight 1.3-GHz cavities produced by two vendors, Research Instruments GmbH in Germany (RI) and Ettore Zanon S.p.a. in Italy (EZ), using niobium cell material from Tokyo Denkai Co., Ltd. (TD) and Ningxia Orient Tantalum Industry Co., Ltd. (OTIC/NX)). During the initial production run, cavity performance from one of the vendors (Vendor A) was far below expectation. All the cavities had low Q0, later attributed to minimal EP as well as high-flux-trapping NX material, early quench behaviour below 18 MV/m, with many having Q0 roll-off at 12-16 MV/m. Production was stopped multiple times over the following 6 months, with test batches of cavities being made to ascertain the root cause of the problem. The final root cause of the problem was found to be inappropriate grinding of the RF surface prior to welding which left normal conducting inclusions in the surface. In addition, most cavities showed internal and external weld spatter which required post weld grinding and a very rough surface from operating the electropolishing machine in an etching rather than polishing regime. All issues have been corrected on new cavities and rework is underway on the originally effected cavities.
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THPAL142	Surface Characterization of NbTiN Films for Accelerator Applications	SRF, FEL, detector, lattice	3975
	D.R. Beverstock, M.J. Kelley, C.E. Reece, J.K. Spradlin, A-M. Valente-Feliciano JLab, Newport News, Virginia, USA
	Funding: Work supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The development of next-generation SRF cavities requires the deployment of innovative material solutions with RF performance beyond bulk Nb. Theoretical interest has stimulated efforts to grow and characterize thin multi-layer superconductor/insulator/superconductor (SIS) structures for their potential capability of supporting otherwise inaccessible surface magnetic fields in SRF cavities . The ternary B1-compound NbTiN is among the candidate superconducting materials for SIS structures. Single crystal NbTiN films with thicknesses below 15 nm are also of interest for the development of high resolution, high sensitivity (SNSPD) detectors for particle physics application. Using DC reactive magnetron sputtering, NbTiN can be deposited with nominal superconducting parameters. This contribution presents the on-going material surface and superconducting properties characterization in order to optimize the NbTiN films for each application. A Gurevich, "Maximum screening fields of superconducting multilayer structures", AIP ADVANCES 5, 017112 (2015)
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THPMK125	Development of Non-Evaporable Getter (NEG) Coatings on Small Diameter Vacuum Chambers for Diffraction-Limited Storage Ring	vacuum, target, electron, storage-ring	4611
	S. Wang, Y.Z. Hong, R. Huang, X.T. Pei, Y. Wang, W. Wei, B. Zhang, S.C. Zhang USTC/NSRL, Hefei, Anhui, People's Republic of China
	Design of the fourth generation Diffraction-Limited Storage Ring reduces aperture of vacuum chambers to a few centimeters. To satisfy the small aperture, the intense photon bombardment and the requirement of low pressure, most of the beam pipes need to be deposited with Ti-Zr-V nonevaporable getter (NEG) thin films. NEG can provide distributed pumping and low gas desorption and allow to achieve low pressure in narrow and conductance limited chambers. In this paper, Ti-Zr-V thin film was deposited by DC magnetron sputtering using Ti-Zr-V alloy target. The morphology and thickness of Ti-Zr-V are characterized by Scanning Electron Microscopy (SEM). The average grain size is evaluated using X-ray diffraction (XRD). The composition and the corresponding chemical bonding of the thin film are analyzed by X-ray Photoelectron Spectroscopy (XPS). Finally, the adhesion between the film and substrate and the vacuum performance are evaluated.
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THPML011	Possibilities for Fabricating Polymer Dielectric Laser Accelerator Structures with Additive Manufacturing	laser, acceleration, electron, lattice	4671
	E.I. Simakov, R.D. Gilbertson, M.J. Herman, G. Pilania, D.Y. Shchegolkov, E.M. Walker, E. Weis LANL, Los Alamos, New Mexico, USA R.J. England, K.P. Wootton SLAC, Menlo Park, California, USA
	Funding: Los Alamos National Laboratory LDRD Program We present results of recent studies of new materials designed for the additive manufacturing of accelerating structures for dielectric laser accelerators (DLAs). Demonstration of a stand-alone practical DLA requires innovation in design and fabrication of efficient laser accelerator structures and couplers. Many complicated three-dimensional structures for laser acceleration (such as a long woodpile structure with couplers) are difficult to manufacture with conventional microfabrication technologies. LANL has a large effort focused on developing new materials and techniques for additive manufacturing. The materials for DLA structures must have high dielectric constant (larger than 4), low loss in the infrared regime, high laser damage threshold, and be able to withstand the electron beam damage. This presentation will discuss the development of novel infrared dielectric materials that are of interest for laser acceleration and are compatible with additive manufacturing, as well as recent advances in additive manufacturing of dielectric woodpile structures using a Nanoscribe direct laser-writing 3D printer.
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THPML062	A Beam Based Method to Optimize the SBPM System	FEL, experiment, electron, quadrupole	4780
	J. Chen SINAP, Shanghai, People's Republic of China L.W. Lai, Y.B. Leng, T. Wu, R.X. Yuan SSRF, Shanghai, People's Republic of China
	For the electron accelerator, it is hoped that the trajec-tory of the beam can pass through the magnetic center of the quadrupole to minimize the orbital motion caused by the instability of the power supply. The relative deviation between the magnetic center of quadrupole and the elec-tric center of adjacent BPM is measured by electron beam usually in various accelerator facilities. But for the stripline BPM (SBPM) system, in order to achieve the best performance, the beam trajectory should also need to pass through the electrical center of the SBPM system. In this paper, a beam based method to optimize the SBPM system was proposed, the intensity of the magnet power was scanned to change the beam position in two-dimension and combine the change trend of the sum signal of adjacent SBPM to find out the relative deviation of BPM electric center and mechanical center. Relevant beam experiment work on the Shanghai Soft X-ray free electron laser (SXFEL) and the benefit of this method will be addressed as well.
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THPML120	Development of Coating Technique for Superconducting Multilayered Structure	cavity, target, experiment, acceleration	4954
	R. Ito, T. Nagata ULVAC, Inc, Chiba, Japan H. Hayano, T. Kubo, T. Saeki KEK, Ibaraki, Japan H. Ito Sokendai, Ibaraki, Japan Y. Iwashita, R. Katayama Kyoto ICR, Uji, Kyoto, Japan H. Oikawa Utsunomiya University, Utsunomiya, Japan
	In order to increase the maximum acceleration gradient of SRF cavities, S-I-S (superconductor-insulator-superconductor) multilayered structure theory has been proposed. We focused on NbN which has a higher superconducting transition temperature than Nb. Firstly, we researched the optimal deposition condition for N2 gas reactive sputtering of NbN by using in-house inter-back type DC magnetron sputtering equipment. The critical condition for a thin film with strong crystalline orientation of NbN was identified. The superconducting transition temperature of the NbN thin film, which were coated under the best condition, was over 14 K. Secondly, we tried making S-I-S multilayered samples that was composed of NbN/SiO2/Nb substrate. The coating condition for the NbN layer was determined based on the research results in a single layer. The SiO2 layer was deposited with a film thickness of 30 nm that was theoretically expected to be effective as barrier layer. We applied O2 gas reactive AC magnetron sputtering for coating. In this article, the detailed results of the NbN single layer and multilayer film depositions are presented.
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THPML128	Production and Secondary Electron Yield Test of Amorphous Carbon Thin Film	electron, vacuum, synchrotron, synchrotron-radiation	4980
	Y.X. Zhang, X.Q. Ge, S.W. Wang, Y. Wang, W. Wei, B. Zhang USTC/NSRL, Hefei, Anhui, People's Republic of China
	Amorphous carbon (a-C) thin film applied to vacuum chambers of high-energy particle accelerators can decrease secondary electron yield（SEY）and suppress electron-cloud effectively. A dc magnetron sputtering apparatus to obtain a-C film has been designed. With the equipment, a-C thin film can be deposited on the inner face of stainless steel pipes ultimately which is uniform and high-quality. Meanwhile, it is found that a-C has a low SEY＜1.2 measured by the secondary electron emission measurement set-up in the National Synchrotron Radiation Laboratory. The result indicates that a-C is an ideal material for modern accelerators.
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Paper

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MOZGBE4

Overview of Fabrication Techniques and Lessons Learned with Accelerator Vacuum Windows

vacuum, Windows, target, operation

51

C.R. Ader, M.W. McGee, L.E. Nobrega, E.A. Voirin
Fermilab, Batavia, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02- 07CH11359 with the U.S. Department of Energy.
Vacuum thin windows have been used in Fermilab's accelerators for decades and typically have been overlooked in terms of their criticality and fragility. Vacuum windows allow beam to pass through while creating a boundary between vacuum and air or high vacuum and low vacuum areas. The design of vacuum windows, including titanium and beryllium windows, will be discussed as well as fabrication, testing, and operational concerns. Failure of windows will be reviewed as well as safety approaches to mitigating failures and extending the lifetimes of vacuum windows. Various methods of calculating the strengths of vacuum windows will be explored, including FEA.

Slides MOZGBE4 [2.155 MB]

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MOPMF021

Ground Motion Measurement and Analysis for HEPS

ground-motion, emittance, ion-source, lattice

125

F. Yan, Z. Duan, D. Ji, Y. Jiao, Z.Z. Wang, Y. Wei, G. Xu
IHEP, Beijing, People's Republic of China

HEPS have very challenging beam stability require-ments. Special cares are mandatory in developing site vibration specifications, stable building design concepts, and passive and active ways to minimize effects on the stability of the photon beam and critical accelerator and beamline components caused by ambient ground motion sources. However, among all these work, reasonable as-sessment of the vibration induced beam instability has to be the first step. This paper will focuses on the measure-ment results of the ground motion on HEPS site, the es-tablishment of reasonable beam dynamic models, the influences of ground motion to the beam of main ring.

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MOPML053

Mu*STAR Accelerator-Driven Subcritical Reactors Burning Spent Nuclear Fuel at Light-Water-Reactor Sites

target, neutron, operation, SRF

524

R.P. Johnson, R.J. Abrams, M.A. Cummings, T.J. Roberts
Muons, Inc, Illinois, USA

This project will use modeling and simulation tools to optimize many aspects of the Mu*STAR design and begin to explore accident scenarios. At present we have a conceptual design of the accelerator, the reactor, the spallation target, and the fractional distillation to separate volatile fission products. Our GAIN project with ORNL is preparing a design of the Fuel Processing Plant that will convert spent nuclear fuel into the molten-salt fuel for Mu*STAR. This includes all of the nuclear components, but not such things as the turbine and generator, physical plant, control and monitoring systems, etc. We currently have basic simulations of the reactor neutronics, and a start at calculating the fuel evolution. These have used MCNP and ORIGEN, and initial results have been reported1. This project will support the use of additional neutronics and multi-physics codes, enabling a much more thorough analysis of the system.

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MOPML070

Thermal and Stress Analysis of an X-Ray Target for 6 MeV Medical Linear Accelerators

target, electron, simulation, photon

572

Z.H. Wang, H.B. Chen, J. Shi, H. Zha
TUB, Beijing, People's Republic of China

We present an optimal design of an X-ray target for 6 MeV medical linear accelerators using FLUKA simula-tions. The target is composed of high-atomic number tungsten and high-thermal conductivity copper, corre-sponding water-cooling system is showed too. Further-more, we analyse the temperature and thermal stress re-sponses of the target under transient thermal loads using Ansys Code. For 6 MeV electron beam with 100 uA cur-rent, the results show that the target can achieve 1014 cGy/min at 1meter in front of the target. Within 100 ms, the maximum temperature reaches 512 °C under pulsed heating source with 250 Hz frequency and 1' duty cycle and the number of cycles to failure is estimated as 5.8·10⁸.

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TUPAF044

Schedule Evolution of the Linac4 Installation During the Lifetime of the Linac4 Project and Connection Forecast

linac, civil-engineering, MMI, status

794

J. Coupard, A. Berjillos, J.-P. Corso, K. Foraz, B. Nicquevert, E. Paulat, M. Vretenar
CERN, Geneva, Switzerland

The new CERN linear accelerator Linac4 started the installation phase in 2010 after the delivery of the new building and tunnel by the civil engineering and was inaugurated six years later. It will be connected to the CERN accelerators chain and replace the current proton linear accelerator, Linac2, during the second long shut-down (LS2) of the Large Hadron Collider (LHC) in 2019. This paper aims to summarize the schedule evolution through the different phases of installation, from general services to machine installation, highlight the key factors that contributed to drive the schedule (safety, logistics and integration) and describe the coordination study of the future connection (integration, schedule, logistics, constraints and priorities).

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TUPAF064

Preparation Towards the Ess Linac Ion Source and Lebt Beam Commissioning on Ess Site

MMI, rfq, linac, solenoid

874

R. Miyamoto, M. Eshraqi, A. Jansson, E. Laface, Y. Levinsen, O. Midttun, N. Milas, M. Muñoz, D.C. Plostinar, A. Ponton, E. Sargsyan, L. Tchelidze
ESS, Lund, Sweden
L. Celona, L. Neri
INFN/LNS, Catania, Italy
W. Ledda
Vitrociset s.p.a, Roma, Italy

Beam commissioning of the proton linac of the European Spallation Source begin in summer, 2018, from the ion source (IS) and low energy beam transport (LEBT), and continues in stages until 2022, when the first beam is sent to its spallation target. This paper presents the plan, status, and highlights of preparation works for the upcoming IS and LEBT beam commissioning.

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TUPAF075

Design Status of the LBNF/DUNE Beamline

target, proton, shielding, status

902

V. Papadimitriou, J.E. Anderson, R. Andrews, J.J. Angelo, V.T. Bocean, C.F. Crowley, A. Deshpande, N. Eddy, K. E. Gollwitzer, S. Hays, P. Hurh, J. Hylen, J.A. Johnstone, P.H. Kasper, T.R. Kobilarcik, G.E. Krafczyk, N.V. Mokhov, D. Pushka, S.D. Reitzner, P. Schlabach, V.I. Sidorov, M. Slabaugh, S. Tariq, L.R. Valerio, K. Vaziri, G. Velev, G.L. Vogel, K.E. Williams, R.M. Zwaska
Fermilab, Batavia, Illinois, USA
C.J. Densham
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom

Funding: DOE, contract No. DE-AC02-07CH11359
The Long Baseline Neutrino Facility (LBNF) will utilize a beamline located at Fermilab to provide and aim a wide band beam of neutrinos of sufficient intensity and appropriate energy toward DUNE detectors, placed 4850 feet underground at SURF in South Dakota, about 1,300 km away. The primary proton beam (60-120 GeV) will be extracted from the MI-10 section of Fermilab's Main Injector. Neutrinos are produced after the protons hit a four-interaction length solid target and produce mesons which are subsequently focused by a set of three magnetic horns into a 194 m long helium filled decay pipe where they decay into muons and neutrinos. The parameters of the facility were determined taking into account the physics goals, spatial and radiological constraints, extensive simulations and the experience gained by operating the NuMI facility at Fermilab. The Beamline facility is designed for initial operation at a proton-beam power of 1.2 MW, with the capability to support an upgrade to about 2.4 MW. LBNF/DUNE obtained CD-1 approval in November 2015 and CD-3a approval in September 2016. We discuss here the Beamline design status and the associated challenges.

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TUPAF083

SIS100 Tunnel Design and Civil Construction Status

status, radiation, experiment, shielding

927

C. Omet, J. Falenski, H. Kisker, K. Konradt, P.J. Spiller
GSI, Darmstadt, Germany
A. Fischer
FAIR, Darmstadt, Germany

As the FAIR Project is proceeding, building designs have been frozen and the according work packages tendered. For the future FAIR main driver accelerator, SIS100, the 1.1 km long accelerator tunnel "T110", has been planned 17 m deep under ground. In this article, environmental boundary conditions, the chosen layout and the current status of civil construction is presented.

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TUPAF084

The First-of-Series SIS100 Cryocatcher

vacuum, cryogenics, HOM, instrumentation

930

L.H.J. Bozyk, Sh. Ahmed, P.J. Spiller
GSI, Darmstadt, Germany

The superconducting heavy ion synchrotron SIS100 of the FAIR-facility will be equipped with 60 cryocatcher, to suppress dynamic vacuum effects. A prototype cryocatcher has been designed, manufactured and underwent several tests. The results yielded in the design of the series cryocatcher. Recently, the First-of-Series cryocatcher has been manufactured and tested. Results from the manufacturing process and the site acceptance tests, including cryogenic test with liquid helium are presented. The FoS cryocatcher sucessfully passed all tests and the series production will be released.

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TUPAL012

Design and Fabrication of Hybrid RFQ Prototype

DTL, rfq, linac, cavity

1032

P.Y. Yu, Y. He, C.X. Li, G.Z. Sun, F.F. Wang, Z.J. Wang, B. Zhang, T.M. Zhu
IMP/CAS, Lanzhou, People's Republic of China

Hybrid RFQ is proposed as a potential good choice at the low-energy range of linear accelerator. The complexi-ty of mechanical design and difficulty of fabrication are part of reasons impeding application of it and similar structures. In order to explore the practicable structure and research on RF parameters of this accelerating struc-ture, an aluminium prototype is developed.

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TUPAL057

Preliminary Experiments in Caesium Delivery and Gettering on the ISIS Vespa Source

experiment, ion-source, plasma, operation

1144

T. M. Sarmento, R.E. Abel, D.C. Faircloth, S.R. Lawrie, J.H. Macgregor, M. Whitehead, T. Wood
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

Caesium capture by graphite at various temperatures 20- 300°C in the VESPA ion source test stand was explored in a preliminary experiment. An accompanying experiment was set up to evaluate the control of caesium boiler delivery in the various ISIS penning sources. Results indicate Cs flux fluctuates at constant settings, which must be accounted for to interpret graphite gettering results. Future studies to identify the cause of fluctuations are considered, and a more rigorous experiment to study the use of graphite is introduced.

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WEPAF018

Proposed BPM-Based Bunch Crabbing Angle Monitor

cavity, simulation, electron, diagnostics

1860

P. Thieberger, M.G. Minty, C. Montag
BNL, Upton, Long Island, New York, USA

Funding: This work was supported by Brookhaven Science Associates, LLC, under Contract No. DE-AC02-98CH10886 with the US Department of Energy.
A tilted bunch traversing a button beam profile monitor will produce signals on opposite pickup electrodes that will have different degrees of distortion depending on the tilt angle. In particular, the zero-crossing time difference between the two signals will be approximately proportional to the tilt angle. We perform simulations to study this effect as a possible diagnostic tool for measuring the crabbing angles in a future electron-ion collider.

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WEPAL049

Simulating Non-Relativistic Beams Using Helical Pulse Lines

impedance, simulation, ECR, GUI

2288

C.J. Richard
NSCL, East Lansing, Michigan, USA
S.M. Lidia
FRIB, East Lansing, USA

Funding: Work supported by the US Department of Energy, Office of Science, High Energy Physics under Cooperative Agreement award number DE-SC0018362.
Benchtop calibration of capacitive beam position monitors (BPMs) in low energy beamlines is challenging due to non-relativistic effects. Typical benchtop calibrations cannot account for these effects because they rely on speed of light fields transmitted along a straight wire. However, it is possible to replicate the electromagnetic fields generated by non-relativistic beams using a helical line pulse instead of a straight wire. In order to properly replicate the fields from a beam, a method must be developed for tailoring input pulses into the helical line to match bunch shape and a model of the impedance of the helix should be developed to assist with matching. This paper uses the sheath helix model to analyze signal propagation along a helical line in the time domain, with attention to dispersive effects and impedance matching. The results from this model are then compared to Microwave Studio simulations.

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WEPAL059

Observation and Suppression of Beam Orbit Drift Due to Path Length Changes and Thermal Effect in TPS

feedback, controls, operation, electron

2313

P.C. Chiu, K.T. Hsu, K.H. Hu, C.H. Huang, C.-C. Kuo
NSRRC, Hsinchu, Taiwan

Tidal effect, ambient temperature fluctuation and other effects of the TPS site can cause the path length changes of the electron beam in the TPS storage ring. Off-energy orbit drifts from the path length change, if not varying the RF frequency, cannot be properly corrected by the horizontal correctors and this causes the fast orbit feedback system over its normal working range. RF frequency adjustment loop is therefore applied to compensate for the circumference change based on the accumulating corrector strengths of the fast orbit feedback system. Implementation and operational experiences will be discussed in the report.

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WEPAL075

Time-Resolved Transverse Beam Profile Measurements with a Rest Gas Ionisation Profile Monitor Based on Hybrid Pixel Detectors

electron, detector, background, proton

2361

S. Levasseur, S.M. Gibson
Royal Holloway, University of London, Surrey, United Kingdom
W. Bertsche, H. Sandberg
UMAN, Manchester, United Kingdom
D. Bodart, A. Huschauer, G. Schneider, J.W. Storey, R. Veness
CERN, Geneva, Switzerland
M. Sapinski
GSI, Darmstadt, Germany
K. Satou
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

A novel rest gas ionisation profile monitor which aims to provide continuous, bunch-by-bunch and turn-by-turn measurement of the transverse beam profile has recently been in- stalled in the CERN Proton Synchrotron (PS) as part of the LHC Injector Upgrade (LIU) project. The instrument consists of an electric drift field to transport ionisation electrons produced by beam-gas interaction onto a measurement plane, and a magnetic field to maintain the transverse position of the ionisation electrons. The electron detector located at the measurement plane is based on four in-vacuum hybrid pixel detectors. The detectors record the position, time and energy of single ionisation electrons with unprecedented precision compared to traditional MCP based techniques. Continuous transverse beam profile measurements for LHC-type beams in the PS will be presented, demonstrating the unique capabilities of the instrument to provide new insights into beam dynamics throughout the acceleration cycle.

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WEPMF014

Fast Track Actively Shielded Nb3Sn IR Quadrupole R&D

quadrupole, hadron, collider, coupling

2398

B. Parker, M. Anerella, J.P. Cozzolino, R.C. Gupta, R.B. Palmer, J. Schmalzle, H. Witte
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The Interaction Region (IR) magnets for future Electron Ion Colliders (EIC), such as eRHIC at BNL, JLEIC at JLab and LHeC at CERN, must satisfy strongly opposing requirements. EIC IR superconducting quadrupole coils must provide strong focusing gradients, leading to large peak fields, for the high momentum hadron beam while permitting the nearby electron beam to pass through a nearly field free region. An actively shielded coil geometry does this using nested, opposite polarity, quadrupoles where the combined external fields cancel while leaving a net gradient inside. In order to fabricate and test this concept in a timely and cost effective manner we propose to reuse the inner coils from an existing high gradient Nb3Sn LARP quadrupole inside a new structure with a new NbTi active shield coil. The main challenge is to design a compact structure for applying prestress to the Nb3Sn coil that fits the restricted space inside the shield coil. We first construct a 15 cm long mechanical model of this structure with coil strain gauges to verify the design concept before proceeding with the full coil. Mechanical modeling results and our preliminary design concept are reported here.

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WEPMF047

Performance of Samples With Novel SRF Materials and Growth Techniques

cavity, SRF, superconducting-RF, niobium

2475

T.E. Oseroff, M. Ge, M. Liepe, J.T. Maniscalco, R.D. Porter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
S.R. McNeal
Ultramet, Pacoima, California, USA
M.J. Sowa
Veeco-CNT, Medford, USA

Novel materials are currently being studied in an attempt to push accelerating superconducting RF cavities to support higher accelerating fields and to operate with lower power loss. Growing layers of these materials of the quality necessary has proven to be difficult. In this work, we present the SRF performance of planar samples of the promising materials, NbN and Nb¬3Sn, grown using atomic layer deposition (ALD) and chemical vapor deposition (CVD) respectively. Results are promising.

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WEPMF050

Update on Nb3Sn Progress at Cornell University

cavity, niobium, SRF, accelerating-gradient

2479

R.D. Porter, J. Ding, D.L. Hall, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
T.A. Arias, P. Cueva, D.A. Muller, N. Sitaraman
Cornell University, Ithaca, New York, USA

Niobium-3 Tin (Nb3Sn) is the most promising alternative material for SRF accelerator cavities. The material can achieve higher quality factors, higher temperature operation and potentially higher accelerating gradients compared to conventional niobium. Cornell University has a leading program to produce 2 - 3 micrometer thick coatings of Nb3Sn on Nb for SRF applications using vapor diffusion. This program has been the first to produce quality factors higher than achievable with conventional Nb at usable accelerating gradients. Here we present an update on progress at Cornell University, including studies of the formation of the Nb3Sn layer, density functional theory calculations of Nb3Sn growth, and designs for a sample host cavity for measuring the quench field of Nb3Sn.

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WEPMF071

Dynamic Testing and Characterization of Advanced Materials in a New Experiment at CERN HiRadMat Facility

experiment, target, damping, proton

2534

A. Bertarelli, C. Accettura, E. Berthomé, L. Bianchi, F. Carra, C. Fichera, M.I. Frankl, G. Gobbi, P. Grosclaude, M. Guinchard, A. Lechner, M. Pasquali, S. Redaelli, E. Rigutto, O. Sacristan De Frutos
CERN, Geneva, Switzerland
Ph. Bolz, P. Simon
GSI, Darmstadt, Germany
T.R. Furness
University of Huddersfield, Huddersfield, United Kingdom
J. Guardia Valenzuela
Universidad de Zaragoza, Zaragoza, Spain
P. Mollicone, M. Portelli
UoM, Msida, Malta

Funding: This work has received funding from the European Union's Horizon 2020 Research and Innovation programme under Grant Agreement No 730871.
An innovative and comprehensive experiment (named "Multimat") was successfully carried out at CERN HiRadMat facility on 18 different materials relevant for Collimators and Beam Intercepting Devices. Material samples, tested under high intensity proton pulses of 440 GeV/c, exceeding the energy density expected in HL-LHC, ranged from very light carbon foams to tungsten heavy alloys, including novel composites as graphite/carbides and metal/diamond without and with thin-film coatings. Experimental data were acquired relying on extensive integrated instrumentation (strain gauges, temperature sensors, radiation-hard camera) and on laser Doppler vibrometer. This allows investigating relatively unexplored and fundamental phenomena as dynamic strength, internal energy dispersion, nonlinearities due to inelasticity and inhomogeneity, strength and delamination of coatings and surfaces. By benchmarking sophisticated numerical simulations against these results, it is possible to establish or update material constitutive models, which are of paramount importance for the design of devices exposed to interaction with particle beams in high energy accelerators such as the HL-LHC or FCC-hh.

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WEPML025

Advantages and Challenges of Nb3Sn Superconducting Undulators

undulator, experiment, operation, photon

2734

A.V. Zlobin, E.Z. Barzi, D. Turrioni
Fermilab, Batavia, Illinois, USA
Y. Ivanyushenkov, I. Kesgin
ANL, Argonne, Illinois, USA

Funding: This work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
Superconducting undulators (SCUs) employ superconducting coils, and due to high critical current density in a superconductor, outperform undulators based on permanent magnets in terms of the level of magnetic field. So far, most of the SCUs, including devices built at Advanced Photon Source (APS), use Nb-Ti superconductor. Utilization of Nb3Sn conductor offers a possibility to increase the undulator field even further but requires to overcome certain challenges that are described in this paper. Based on experience of developing Nb3Sn accelerator magnets at Fermi National Accelerator Laboratory, possible solutions are discussed. The achievable field levels for Nb3Sn version of existing APS and the future APS-Upgrade superconducting undulators are also presented and discussed.

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WEPML067

Second Sound Quench Detection on Superconducting Cavities

cavity, detector, SRF, superconducting-cavity

2843

Z.C. Liu, S. Bai, J. Gao, F.S. He, H.Y. Lin, P. Zhang
IHEP, Beijing, People's Republic of China

Second sound is an effective way to detect the quench position on superconducting cavity. A second sound quench site detection system is under developing for the PAPS. High gradient is very important for superconducting cavity, however it may be limited by quench on the cavity high field region. Quench can be caused by various reasons. To locate the position is the key to reveal the mysteries of quench. Now we are developing the quench position detection system by RTD sensors such as Cernox and OST sensors.

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WEPML075

Test of Magnet Girder Prototypes for HEPS-TF

alignment, coupling, HOM, photon

2863

H. Wang, C. H. Li, S.J. Li, J. Liu, H. Qu, Z. Wang, L. Wu
IHEP, Beijing, People's Republic of China
H.Y. Zhu
Institute of High Energy Physics (IHEP), People's Republic of China

Auto-tuning magnet girder is one of the key technolo-gies to be solved for HEPS-TF (Test Facility of High Ener-gy Photon Source). The girder should have high adjusting accuracy, high stability and can be beam-based aligned, to obtain the stability requirements of beam orbit. There are two girders developed, and the tests have been done. The accuracy of girder motion is within 10 microns while the adjusting range is 1 mm and the resolution is better than 1 microns, the natural frequency is higher than 24 Hz.

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THPAF026

Modeling Studies for Synchrotron-Radiation-Induced Electron Production in the Vacuum Chamber Walls at CesrTA

photon, electron, simulation, vacuum

3011

S. Poprocki, J.A. Crittenden, D. L. Rubin, D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467 and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505.
We report on calculations of electron production by synchrotron radiation absorbed in the vacuum chamber walls of the Cornell Electron Storage Ring (CESR). These electrons are the source of electron clouds which limit the performance of storage rings by causing betatron tune shifts, instabilities and emittance growth. Until now, cloud buildup modeling codes have used ad hoc models of the production of the seed electrons. We have employed the photon scattering code Synrad3D to quantify the pattern of absorbed photons around the CESR ring, including the transverse distribution on the wall of the beam-pipe. These distributions in absorbed photon energy and incident angle are used as input to Geant4-based simulations of electron emission from the walls. The average quantum efficiency is found to vary dramatically with the location of the absorption site, owing to the distribution in impact energies and angles. The electron production energy spectrum plays an important role in the modeling of electron cloud buildup, where the interplay of production energy and acceleration by the beam bunches determines the time structure and multipacting characteristics of the cloud.

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THPAF047

Measurements and Impact of Stray Fields on the 380 GeV Design of CLIC

emittance, dipole, collider, background

3072

C.G. Gohil, M.C.L. Buzio, E. Marín, D. Schulte
CERN, Geneva, Switzerland
P. Burrows
JAI, Oxford, United Kingdom

Previous studies of the 3 TeV Compact Linear Collider (CLIC) design have shown a sensitivity to external dynamic magnetic fields (stray fields) on the nanoTesla level. In this paper the obtained tolerances for stray fields in the 380 GeV CLIC design are presented. In order to determine potential stray field sources, a measurement sensor has been acquired and used to investigate the magnetic contamination from technical equipment. The collected measurements, as well as details of the sensor, are discussed.

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THPAL031

Development of a Vertical Electropolishing Facility for Nb 9-Cell Cavity

cavity, niobium, cathode, controls

3699

Y.I. Ida, V. Chouhan, K.N. Nii
MGH, Hyogo-ken, Japan
akabori. Akabori, G.M. Mitoya, K. Miyano
HKK, Morioka, Japan
Y. Anetai, F. Takahashi
WING. Co.Ltd, Iwate-ken, Japan
H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan

Our Nb accelerating cavity vertical electropolishing (VEP) facility development group which was led by KEK started single-cell VEP facility development from 2014. This is based on horizontal electropolishing (HEP) techniques developed by KEK over 10 years and stainless steel electropolishing techniques developed by Marui over 30 years. We have reported results of Nb cavity VEP with Ninja cathode so far. In order to achieve international linear collider (ILC) construction, it is said that cost reduction and productivity improvement are necessary, however in case of 9-cell cavity, uniform inner surface polishing is difficult, as well known to predecessors. In this article, we will present the first report of VEP facility development from initial transparent plastic mock-up to improvement for Nb 9-cell cavity.

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THPAL036

Nb3Sn Thin Films for the Production of Higher Gradient SRF Cavities at Reduced Cost

cavity, niobium, SRF, superconductivity

3716

S.A. Kahn, M.A. Cummings
Muons, Inc, Illinois, USA
E.Z. Barzi, D. Turrioni
Fermilab, Batavia, Illinois, USA
S. Falletta
Politecnico di Torino, Torino, Italy
A. Kikuchi
NIMS, Tsukuba, Ibaraki, Japan

High gradient superconducting cavities (SRF) will be needed for future accelerators. The higher gradient can achieve the high energy with fewer cavities. However the accelerating field of niobium cavities is limited by the peak magnetic field on the cavity surface. Cavities coated with Nb3Sn have a significantly larger Hc2 allowing the cavity to achieve a larger gradient. Measurements of Nb3Sn coated cavities have achieved about half the theoretical predicted gradient. It is possible to improve Nb3Sn plated cavity performance.

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THPAL040

Lossy Beam Pipe HOM Load Ceramics with DC Conductivity

experiment, vacuum, HOM, controls

3729

M.L. Neubauer, A. Dudas
Muons, Inc, Illinois, USA
F. Marhauser
JLab, Newport News, Virginia, USA

The ceramic materials used in the beam pipe for super-conducting RF accelerators have the problem of charging due to the electron cloud and secondary electron emission. A novel solution is in the application of conductive nanoparticles to the lossy ceramic. The lossy ceramic is pre-processed to provide for pores that will accept the conductive nanoparticles and then coated with a thin film to prevent the nanoparticles from entering the environment. The same process was also done with sub-micron carbon particles. Measurements of surface conductivity with and without a vacuum compatible sealant are reported on along with microwave measurements.

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THPAL042

Injection Locked 1497 MHz Magnetron

injection, superconducting-cavity, cavity, medical-accelerators

3736

M.L. Neubauer, A. Dudas, S.A. Kahn
Muons, Inc, Illinois, USA
R.A. Rimmer, H. Wang
JLab, Newport News, Virginia, USA

A novel injection-locked 1497 MHz 13 kW AM magnetron design is presented. The anode design to minimized eddy currents due to the changing magnetic field is presented. Thermal calculations of two design options are also presented. An extra degree of freedom in the anode construction is made possible by the fact that the magnetron is injection locked. This fact presents some additional design details that can be utilized in the cooling network for the magnetron anode.

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THPAL050

Beam Dynamics of the First Beams for the IFMIF-EVEDA RFQ Commissioning

operation, controls, storage-ring, synchrotron

3754

C.S. Chen, W.S. Chan, Y.Y. Cheng, Y.-C. Chung, C.Y. Liu, Y.-H. Liu, Z.-D. Tsai
NSRRC, Hsinchu, Taiwan

Since December 31th 2014, the first synchrotron light from Taiwan Photon Source (TPS) was stored in the storage ring, the challenge to operate both Taiwan Light Source (TLS) and TPS smoothly and reliably became a significant issue for all members in NSRRC. On the one hand, the beam quality of former TLS must not been impaired due to the occupied resources by TPS, on the other hand, the most efforts were devoted to achieving steady operation of TPS. In order to operate both ring stably, some mutual backup structures were designed in the compressed air system and the chilled water system between TLS and TPS. The primary advantage of these mutual backup systems is minimizing the risk of beam-trip while any one of the utility system fails. Secondly, the mutual backup structures provide more flexible usage to accomplish energy conservation. From both risk-reduction and energy conservation points of view, the backup systems will do a great deal of good in the future.

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THPAL059

TEMPERATURE ISSUES OF THE TPS BPMS

impedance, wakefield, simulation, resonance

3781

Y.T. Huang, C.-C. Chang, C.M. Cheng, P.J. Chou, Y.C. Yang
NSRRC, Hsinchu, Taiwan

Since the TPS is capable to operate at higher currents, long-term 400mA conditioning runs were conducted. Current-dependent temperature data of BPMs were collected and analysed for both, aluminium and stainless steel BPM chambers. To better understand beam coupling effects in different types of TPS BPMs, electromagnetic and thermal simulation models were established. In this paper, we discuss associated results of such studies.

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THPAL089

Design, Assembly and Commissioning of a New Cryogenic Facility for Complex Superconducting Thin Film Testing

SRF, experiment, cavity, operation

3859

O.B. Malyshev, L. Bizel-Bizellot, K.D. Dumbell, P. Goudket, N. Pattalwar, S.M. Pattalwar, P. Pizzol, P.A. Smith, R. Valizadeh, S. Wilde
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
P. Pizzol
The University of Liverpool, Liverpool, United Kingdom

An ongoing study on the superconducting thin films for future superconducting RF cavities requires an intense testing of various superconducting properties. We have designed, built and tested a new facility for complex superconducting thin film testing that includes: (1) RRR measurement with and without magnetic field, (2) planar and (3) tubular magnetic field penetration experiments, (4) a superconducting coaxial resonator for bulk niobium and superconducting thin film characterisation. The system is based on a closed cycle refrigerator, eliminating the need for liquid helium, thus making it simple and safe to operate. The details of the design and commissioning will be presented at the conference.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL089

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THPAL098

Pumping Properties of Single Metal Zirconium Non-Evaporable Getter Coating

vacuum, target, experiment, injection

3869

Sirvinskaite, R. Sirvinskaite, M.D. Cropper, M.D. Cropper
Loughborough University, Loughborough, Leicestershire, United Kingdom
A.N. Hannah, O.B. Malyshev, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
O.B. Malyshev, R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Non-evaporable getter (NEG) coating has been used for years in many particle accelerator facilities due to its evenly distributed pumping speed, low thermal outgassing, and low photon and electron stimulated desorption yields. We have previously demonstrated that quaternary Ti-Zr-Hf-V coating deposited from an alloy wire has the lowest desorption yields, the highest sticking probability and sorption capacity. In this work, we explore the single element targets which are widely available and can be produced in a form of a wire that is easy to apply for a uniform coating of various shapes of vacuum chamber. Single metal Zr coatings have been tested to find a more efficient and cheaper way of producing the NEG-coated vacuum chambers. Two samples coated with Zr of dense and columnar structure were analysed and results of the pumping properties are reported. The results show that pure Zr coating could be an economic solution, despite not being as effective as can be achieved with quaternary NEG film. It shows that columnar Zr coating can be activated and reaches full pumping capacity at 160°C. This is close to the activation temperature of Ti-Zr-Hf-V and lower than that for the widely used ternary Ti-Zr-V alloy.

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THPAL129

Magnetron Sputtering of Nb3Sn for SRF Cavities

cavity, SRF, target, controls

3946

MNS. Sayeed, H. Elsayed-Ali
ODU, Norfolk, Virginia, USA
G.V. Eremeev, M.J. Kelley, C.E. Reece
JLab, Newport News, Virginia, USA
M.J. Kelley, U. Pudasaini
The College of William and Mary, Williamsburg, Virginia, USA
M.J. Kelley
Virginia Polytechnic Institute and State University, Blacksburg, USA

Nb3Sn is a potential candidate for surface material of SRF cavities since it can enable the cavity to operate at higher temperatures with high quality factor and at an increased accelerating gradient. Nb-Sn films were deposited using magnetron sputtering of individual Nb and Sn targets onto Nb and sapphire substrates. The as-deposited films were annealed at 1200 °C for 3 hours. The films were characterized for their structure by X-ray Diffraction (XRD), morphology by Field Emission Scanning Electron Microscopy (FESEM), and composition by Energy Dispersive X-ray Spectroscopy (EDS) and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The surface resistivity was measured down to cryogenic temperature to determine the superconducting transition temperature and its width. The composition of the multilayered films was controlled by varying the thickness of the Nb and Sn layers. The films showed crystalline Nb3Sn phases with Tc up to 17.6 K.

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THPAL140

Rework Recipe Development, Analysis and Results of Select 9-Cell Cavities for LCLS-II

cavity, embedded, niobium, linac

3968

A.D. Palczewski, K. Macha, H. Park, C.E. Reece, K.M. Wilson
JLab, Newport News, Virginia, USA
A. Burrill, D. Gonnella
SLAC, Menlo Park, California, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The SLAC National Accelerator Laboratory is currently constructing a major upgrade to its accelerator, the Linac Coherent Light Source II (LCLS-II). Several Department of Energy laboratories, including the Thomas Jefferson National Accelerator Facility (JLab) and Fermi National Accelerator Laboratory (FNAL), are collaborating in this project. The cryomodules for this project each consist of eight 1.3-GHz cavities produced by two vendors, Research Instruments GmbH in Germany (RI*) and Ettore Zanon S.p.a. in Italy (EZ*), using niobium cell material from Tokyo Denkai Co., Ltd. (TD) and Ningxia Orient Tantalum Industry Co., Ltd. (OTIC/NX)). During the initial production run, cavity performance from one of the vendors (Vendor A) was far below expectation. All the cavities had low Q0, later attributed to minimal EP as well as high-flux-trapping NX material, early quench behaviour below 18 MV/m, with many having Q0 roll-off at 12-16 MV/m. Production was stopped multiple times over the following 6 months, with test batches of cavities being made to ascertain the root cause of the problem. The final root cause of the problem was found to be inappropriate grinding of the RF surface prior to welding which left normal conducting inclusions in the surface. In addition, most cavities showed internal and external weld spatter which required post weld grinding and a very rough surface from operating the electropolishing machine in an etching rather than polishing regime. All issues have been corrected on new cavities and rework is underway on the originally effected cavities.

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THPAL142

Surface Characterization of NbTiN Films for Accelerator Applications

SRF, FEL, detector, lattice

3975

D.R. Beverstock, M.J. Kelley, C.E. Reece, J.K. Spradlin, A-M. Valente-Feliciano
JLab, Newport News, Virginia, USA

Funding: Work supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The development of next-generation SRF cavities requires the deployment of innovative material solutions with RF performance beyond bulk Nb. Theoretical interest has stimulated efforts to grow and characterize thin multi-layer superconductor/insulator/superconductor (SIS) structures for their potential capability of supporting otherwise inaccessible surface magnetic fields in SRF cavities *. The ternary B1-compound NbTiN is among the candidate superconducting materials for SIS structures. Single crystal NbTiN films with thicknesses below 15 nm are also of interest for the development of high resolution, high sensitivity (SNSPD) detectors for particle physics application. Using DC reactive magnetron sputtering, NbTiN can be deposited with nominal superconducting parameters. This contribution presents the on-going material surface and superconducting properties characterization in order to optimize the NbTiN films for each application.
* A Gurevich, "Maximum screening fields of superconducting multilayer structures", AIP ADVANCES 5, 017112 (2015)

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THPMK125

Development of Non-Evaporable Getter (NEG) Coatings on Small Diameter Vacuum Chambers for Diffraction-Limited Storage Ring

vacuum, target, electron, storage-ring

4611

S. Wang, Y.Z. Hong, R. Huang, X.T. Pei, Y. Wang, W. Wei, B. Zhang, S.C. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Design of the fourth generation Diffraction-Limited Storage Ring reduces aperture of vacuum chambers to a few centimeters. To satisfy the small aperture, the intense photon bombardment and the requirement of low pressure, most of the beam pipes need to be deposited with Ti-Zr-V nonevaporable getter (NEG) thin films. NEG can provide distributed pumping and low gas desorption and allow to achieve low pressure in narrow and conductance limited chambers. In this paper, Ti-Zr-V thin film was deposited by DC magnetron sputtering using Ti-Zr-V alloy target. The morphology and thickness of Ti-Zr-V are characterized by Scanning Electron Microscopy (SEM). The average grain size is evaluated using X-ray diffraction (XRD). The composition and the corresponding chemical bonding of the thin film are analyzed by X-ray Photoelectron Spectroscopy (XPS). Finally, the adhesion between the film and substrate and the vacuum performance are evaluated.

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THPML011

Possibilities for Fabricating Polymer Dielectric Laser Accelerator Structures with Additive Manufacturing

laser, acceleration, electron, lattice

4671

E.I. Simakov, R.D. Gilbertson, M.J. Herman, G. Pilania, D.Y. Shchegolkov, E.M. Walker, E. Weis
LANL, Los Alamos, New Mexico, USA
R.J. England, K.P. Wootton
SLAC, Menlo Park, California, USA

Funding: Los Alamos National Laboratory LDRD Program
We present results of recent studies of new materials designed for the additive manufacturing of accelerating structures for dielectric laser accelerators (DLAs). Demonstration of a stand-alone practical DLA requires innovation in design and fabrication of efficient laser accelerator structures and couplers. Many complicated three-dimensional structures for laser acceleration (such as a long woodpile structure with couplers) are difficult to manufacture with conventional microfabrication technologies. LANL has a large effort focused on developing new materials and techniques for additive manufacturing. The materials for DLA structures must have high dielectric constant (larger than 4), low loss in the infrared regime, high laser damage threshold, and be able to withstand the electron beam damage. This presentation will discuss the development of novel infrared dielectric materials that are of interest for laser acceleration and are compatible with additive manufacturing, as well as recent advances in additive manufacturing of dielectric woodpile structures using a Nanoscribe direct laser-writing 3D printer.

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THPML062

A Beam Based Method to Optimize the SBPM System

FEL, experiment, electron, quadrupole

4780

J. Chen
SINAP, Shanghai, People's Republic of China
L.W. Lai, Y.B. Leng, T. Wu, R.X. Yuan
SSRF, Shanghai, People's Republic of China

For the electron accelerator, it is hoped that the trajec-tory of the beam can pass through the magnetic center of the quadrupole to minimize the orbital motion caused by the instability of the power supply. The relative deviation between the magnetic center of quadrupole and the elec-tric center of adjacent BPM is measured by electron beam usually in various accelerator facilities. But for the stripline BPM (SBPM) system, in order to achieve the best performance, the beam trajectory should also need to pass through the electrical center of the SBPM system. In this paper, a beam based method to optimize the SBPM system was proposed, the intensity of the magnet power was scanned to change the beam position in two-dimension and combine the change trend of the sum signal of adjacent SBPM to find out the relative deviation of BPM electric center and mechanical center. Relevant beam experiment work on the Shanghai Soft X-ray free electron laser (SXFEL) and the benefit of this method will be addressed as well.

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THPML120

Development of Coating Technique for Superconducting Multilayered Structure

cavity, target, experiment, acceleration

4954

R. Ito, T. Nagata
ULVAC, Inc, Chiba, Japan
H. Hayano, T. Kubo, T. Saeki
KEK, Ibaraki, Japan
H. Ito
Sokendai, Ibaraki, Japan
Y. Iwashita, R. Katayama
Kyoto ICR, Uji, Kyoto, Japan
H. Oikawa
Utsunomiya University, Utsunomiya, Japan

In order to increase the maximum acceleration gradient of SRF cavities, S-I-S (superconductor-insulator-superconductor) multilayered structure theory has been proposed. We focused on NbN which has a higher superconducting transition temperature than Nb. Firstly, we researched the optimal deposition condition for N2 gas reactive sputtering of NbN by using in-house inter-back type DC magnetron sputtering equipment. The critical condition for a thin film with strong crystalline orientation of NbN was identified. The superconducting transition temperature of the NbN thin film, which were coated under the best condition, was over 14 K. Secondly, we tried making S-I-S multilayered samples that was composed of NbN/SiO2/Nb substrate. The coating condition for the NbN layer was determined based on the research results in a single layer. The SiO2 layer was deposited with a film thickness of 30 nm that was theoretically expected to be effective as barrier layer. We applied O2 gas reactive AC magnetron sputtering for coating. In this article, the detailed results of the NbN single layer and multilayer film depositions are presented.

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THPML128

Production and Secondary Electron Yield Test of Amorphous Carbon Thin Film

electron, vacuum, synchrotron, synchrotron-radiation

4980

Y.X. Zhang, X.Q. Ge, S.W. Wang, Y. Wang, W. Wei, B. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Amorphous carbon (a-C) thin film applied to vacuum chambers of high-energy particle accelerators can decrease secondary electron yield（SEY）and suppress electron-cloud effectively. A dc magnetron sputtering apparatus to obtain a-C film has been designed. With the equipment, a-C thin film can be deposited on the inner face of stainless steel pipes ultimately which is uniform and high-quality. Meanwhile, it is found that a-C has a low SEY＜1.2 measured by the secondary electron emission measurement set-up in the National Synchrotron Radiation Laboratory. The result indicates that a-C is an ideal material for modern accelerators.

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