IPAC2018 - List of Keywords (pick-up)

Paper	Title	Other Keywords	Page
TUPAF011	Btrain Calibration with RF-Master Method	dipole, cavity, synchrotron, injection	679
	L. Falbo, E. Bressi, M. Pezzetta, C. Priano CNAO Foundation, Milan, Italy
	CNAO is the only Italian hadrontherapy facility able to treat tumors with beams of protons and carbon ions. It is based on a synchrotron with a 77 m ring equipped with 16 normal conducting dipoles characterized by a long delay in the field stabilization. B-Train system is a fundamental device of the whole machine; it is used in feedback to the dipole power supply in order to regulate the magnetic field reducing the natural stabilization times that would cause long treatments. B-Train system allows to obtain the magnetic field starting from measurements of magnetic field changes: it works as an integrator and then it needs a system to reset the counts compensating the electronic and numerical drift of the system itself. An innovative method has been implemented at CNAO to reset Btrain counts exploiting beam measurements after the RF cavity trapping. This procedure has the advantage to avoid external and additional element like NMR probes. The paper shows the use of B-train system at CNAO and its calibration with this method, called "RF-master method".
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF011
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TUPAF036	Studies of the Injection and Cooling Efficiency in LEIR Using the Longitudinal Schottky Spectrum	injection, linac, diagnostics, electron	765
	S. Hirlaender, R. Alemany-Fernández, H. Bartosik, N. Biancacci, V. Kain CERN, Geneva, Switzerland
	The CERN Low Energy Ion Ring (LEIR) has two main operational beams with their associated cycles, the so-called EARLY and the NOMINAL beam. The EARLY beam consists of a single injected pulse from the LINAC3 accelerator, whereas seven consecutive injections are accumulated, and electron cooled for the NOMINAL beam. In both cases, the longitudinal Schottky monitor allows assessing the longitudinal particle distribution during the cooling process on the injection plateau. A method has been established to analyze the Schottky signal, reconstruct the initial particle momentum distribution and derive relevant parameters such as the cooling time, energy off-set of injected and stacked beam or the momentum distribution of the lost beam. The variations of the obtained parameters and the impact on the LEIR performance will be addressed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF036
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TUPAF078	Recent Results of HESR Original Stochastic Cooling Tanks at COSY	kicker, experiment, storage-ring, hardware	913
	R. Stassen, B. Breitkreutz, N. Shurkhno FZJ, Jülich, Germany
	The High Energy Storage Ring (HESR) of the FAIR project at GSI Darmstadt will be very important for different scientific programs due to the modularized start version of FAIR. Stochastic cooling together with barrier bucket operation will be the key component to fulfill the requirements of the different experiments. First pickup and first kicker of the HESR stochastic cooling system have been installed into the COSY accelerator at FZJ Jülich. COSY is well suited to test the performance of the HESR stochastic cooling hardware at different energies and variable particle numbers. The novel dedicated HESR-structures were already successfully tested at the Nuclotron in Dubna for longitudinal cooling and during a beam time 2017 for transverse cooling at COSY. The results of the last stochastic cooling beam time will be presented as well as the first use of GaN based amplifiers in a stochastic cooling system. The HESR needs fast transmission-lines between PU and KI. Beside air-filled coax-lines, optical hollow fiber-lines are very attractive. First results with such a hollow fiber used for the transverse signal path will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF078
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TUPAF079	Scaled Alvarez-Cavity Model Investigations for the UNILAC Upgrade	DTL, cavity, simulation, alignment	916
	M. Heilmann, X. Du, L. Groening, M. Kaiser, S. Mickat, M. Vossberg GSI, Darmstadt, Germany A. Seibel IAP, Frankfurt am Main, Germany
	The 1:3 scaled aluminum model of an Alvarez-type cavity with 10 gaps was used for comparison of simulation with measurement for the frequency and the electric field on axis. The scaled frequency is 325.224 MHz and an Alvarez cavity has a small frequency tuning range. With this scaled model it was possible to apply different stem configurations for each drift tube to damp parasitic modes and to increase the field stability. The new drift tubes have an optimized free-formed profile on the end plates in order to increase the shunt impedance. In special the assembly, positioning and alignment of the drift tubes can be tested and the frequency change can be investigated in this respect.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF079
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TUPAL033	Time-of-Flight, Beam-Energy Measurement of the LANSCE 805-MHz Linac	linac, proton, controls, DTL	1075
	Y.K. Batygin, F.E. Shelley, H.A. Watkins LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396. Control of the beam-energy ramp along the length of a proton linear accelerator is required to keep the accelerator tuned according to design. Historically, the values of the field amplitudes and phases of the side-coupled, 805-MHz LANSCE linac modules are maintained using a well-known delta-t tuning procedure. Time-of-flight measurements of the proton beam energy are now also being used to confirm and improve the overall control of the energy ramp along the linac. The time-of-flight method uses measurements of the difference in RF phases measured as the beam passes installed delta-t pickup loops. A newly developed chassis to control the 3D position of the beam centroid is used. Details of the procedure and results of measurements are presented. K.R.Crandall, "The Delta-T Tuneup Procedure for the LAMPF 805-MHz Linac", LANL Report LA-6374-MS, June 1976.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL033
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TUPMF034	Measuring the Electrical Center and Field Flatness of 704 MHz Deflecting Cavity for LEReC with Wire Stretching System	cavity, simulation, diagnostics, experiment	1320
	T. Xin, J.M. Brennan, J.C.B. Brutus, K. Mernick, K.S. Smith, B. P. Xiao, A. Zaltsman BNL, Upton, Long Island, New York, USA W. Johnson SBU, Stony Brook, New York, USA H. Wang JLab, Newport News, Virginia, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. 704 MHz deflecting cavity was designed for the Low Energy RHIC electron Cooling (LEReC) project. The cavity will serve as a major component in diagnostic line. In LEReC project the requirement on the energy spread of the electron beam is extremely high (better than 10^-4) and the diagnostic system has to to be designed accordingly. The 704 MHz transverse deflecting cavity provides the vertical kick to the beam after it passes through the dispersion dipole so that we can measure the energy spread of the core of the bunch. Traditional way of determining the electrical center of the cavity involves the needle pulling and integration of the signal which is prone to the cumulative error. We present the measurement result from a wire stretching system that is much more efficient and accurate compared to the bead/needle pulling method. Both simulation and experimental results are shown in this paper and the potential in further application is discussed at the end.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF034
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WEPAF019	Fast Readout Algorithm for Cylindrical Beam Position Monitors Providing Good Accuracy for Particle Bunches with Large Offsets	simulation, FPGA, electron, collider	1864
	P. Thieberger, D.M. Gassner, R.L. Hulsart, R.J. Michnoff, T.A. Miller, M.G. Minty, Z. Sorrell BNL, Upton, Long Island, New York, USA A.C. Bartnik Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, 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 simple, analytically correct algorithm is developed for calculating 'pencil' beam coordinates using the signals from an ideal cylindrical beam position monitor (BPM) with four pickup electrodes (PUEs) of infinitesimal widths. The algorithm is then applied to simulations of realistic BPMs with finite width PUEs. Surprisingly small deviations are found. Simple empirically determined correction terms reduce the deviations even further. Finally, the algorithm is used to study the impact of beam-size upon the precision of BPMs in the non-linear region. As an example of the data acquisition speed advantage, a FPGA-based BPM readout implementation of the new algorithm has been developed and characterized
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF019
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WEPAF024	Turn-by-Turn Position Measurements at CNAO with the Libera Spark HR Prototype	hadron, electronics, instrumentation, electron	1870
	M. Cargnelutti, M. Žnidarčič I-Tech, Solkan, Slovenia G.M.A. Calvi, A. Parravicini, E. Rojatti, C. Viviani CNAO Foundation, Milan, Italy
	CNAO in Pavia is one of the first centers for hadrontherapy in Europe, treating patients since 2011. The center is an international reference for a whole new concept of machines being constructed for this purpose. The synchrotron BPM electronics is based on analog boards that compute the ratio between difference and sum signals from the shoebox pickup, later acquired by digital cards. Although the system operates reliably, it just calculates the position with 1kHz rate, while the revolution frequency ranges from 0.5 to 3 MHz. To extend the measurement possibilities for these new hadron synchrotrons, Instrumentation Technologies is developing a data acquisition system capable of acquiring the pickup signals with 125MSps ADCs and calculating bunchbybunch positions of the accelerated beam. The first prototype was tested at CNAO: the turnbyturn beam position was analyzed off line, at different energies and positions with both Protons and Carbon ions beam. This paper will presents the results achieved with the system and compares them with the measurements of the current system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF024
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WEPAF049	Energy Beam Position Monitor Button Array Electronics for the European XFEL	electron, FEL, vacuum, electronics	1927
	B. Lorbeer, B. Beutner, H.T. Duhme, L. Fröhlich, D. Lipka, D. Nölle DESY, Hamburg, Germany
	The European XFEL(X-Ray Free Electron Laser) at DESY(Deutsches Elektronen-Synchrotron) in Hamburg/Schenefeld started commissioning in early 2017. Before the pulsed electron beam is accelerated to its final energy of 14 GeV, the energy of the bunch can be compressed in three bunch compression chicanes at 130 MeV, 700 MeV and 2400 MeV. The vacuum chamber in these sections is tapered from 40 mm round beam pipe to a 40 cm rectangular shaped vacuum section. A custom made button array type of BPM(Beam position Monitor) is installed in this section with 26 button electrode feed-throughs. The analog and digital readout electronics for this monitor and the first experience with the calibration and operational aspects of this system are presented in this poster.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF049
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WEPAF059	A Low Cost Beam Position Monitor System	electron, electronics, hardware, target	1961
	C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA J.G. Power, J.H. Shao ANL, Argonne, Illinois, USA C. Yin University of Chicago, Chicago, Illinois, USA
	A Beam Position Monitor (BPM) system is essential to beam diagnostics for almost all particle accelerators. However, a typical BPM system contains customized hardware and complicated processing electronics which considerably drive the cost for large facilities where hundreds of them may be used. It also limits its use in the small scale accelerator facilities. In the paper, we present a low cost BPM system which consists of a commercial available CF flange based signal pickup device, a low cost integrated circuit adjacent to the pickup to filter, sample, digitize, and broadcast the signals out of the pickup electrodes. The digital signal is transmitted out for post processing through noise-protected Wi-Fi router. We will briefly discuss the working principle and experimental progress to date.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF059
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WEPAF080	Beam Size Measurements Based on Movable Quadrupolar Pick-ups	emittance, alignment, embedded, quadrupole	2028
	A. Sounas, M. Gąsior, T. Lefèvre, A. Mereghetti, J. Olexa, S. Redaelli, G. Valentino CERN, Geneva, Switzerland
	Measurements with quadrupolar pick-ups (PU) have attracted particular interest as non-intercepting diagnostics for determining the transverse beam size. They are based on processing the signals of an electromagnetic PU for the extraction of the second-order moment, which contains information about the beam size. Despite the simplicity of the concept, quadrupololar measurements have always been highly challenging in reality. This comes from the fact that the quadrupolar moment constitutes only a very small part of the total PU signal dominated by the intensity and the position signals. Therefore, the beam size information can easily be lost due to small imperfections in the signal processing chain, such as asymmetries in the electronics and cables. In this paper, we present a new method for quadrupolar measurements using movable PUs. Through position and aperture scans, our technique minimizes the parasitic beam position signal and takes into account imperfections of the PU, cables and electronics, thus enabling an efficient auto-calibration of the measurement system. Preliminary studies, using collimators with embedded electrostatic PUs in the LHC at CERN, have shown very promising results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF080
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WEPAF085	Upgrade of the CERN SPS Beam Position Measurement System	electron, electronics, proton, FPGA	2047
	M. Wendt, M. Barros Marin, A. Boccardi, T.B. Bogey, V. Kain, C. Moran Guizan, A. Topaloudis CERN, Geneva, Switzerland I. Degl'Innocenti Università di Pisa, Pisa, Italy
	The CERN Super Proton Synchrotron (SPS) is a fast cycling hadron accelerator delivering protons with momenta of up to 450 GeV/c for the Large Hadron Collider (LHC), fixed target experiments and other users such as the AWAKE plasma acceleration experiment, and also used to accelerate heavy ions. This paper presents the upgrade initiative for the SPS beam position measurement system in the frame of the CERN LHC Injector Upgrade (LIU) project. The new SPS beam position read-out electronics will be based on logarithmic amplifiers, using signals provided by the 216 existing beam position monitors, the majority of which are based on split-plane 'shoebox' technology. It will need to cover a dynamic range sufficient to manage the wide range of SPS beam intensities and bunch formatting schemes to provide turn-by-turn and averaged beam orbits along the SPS acceleration cycles. In order to avoid long coaxial cables, the front-end electronics including the digitisation, will be located inside the accelerator tunnel, with optical transmission to surface processing electronics. This represents an additional challenge in terms of radiation tolerance of electronics components and materials.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF085
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WEPAK005	A Cryogenic Current Comparators (CCC) Customized for FAIR-Project	niobium, shielding, cryogenics, electronics	2088
	J. Golm, R. Neubert, F. Schmidl, P. Seidel FSU Jena, Jena, Germany J. Golm, T. Stöhlker, V. Tympel HIJ, Jena, Germany D.M. Haider, F. Kurian, M. Schwickert, T. Sieber, T. Stöhlker GSI, Darmstadt, Germany R. Neubert Thuringia Observatory Tautenburg, Tautenburg, Germany M. Schmelz, R. Stolz IPHT, Jena, Germany T. Stöhlker IOQ, Jena, Germany V. Zakosarenko Supracon AG, Jena, Germany
	The principle of non-destructive measurement of ion beams by detection of the azimuthal magnetic field, using low temperature Superconducting Quantum Interference Device (SQUID) sensors, has been established at GSI already in the mid 90's. After more recent developments at Jena, GSI and CERN, a CCC was installed in the CERN Antiproton Decelerator (AD) and is operated there routinely as the first stand-alone CCC system. For the Facility for Antiproton and Ion Research (FAIR) a new version of the CCC with eXtended Dimensions (CCC-XD) - especially with a larger inner diameter and adapted parameters - was constructed and first lab tests have already been performed. In parallel, a concept for a dedicated UHV beamline cryostat has been worked out. The CCC-XD system - together with the new cryostat - will be ready for testing in the CRYRING at GSI before the end of 2018. In this contribution, experimental results for the resolution, frequency range, slew rate and pulse-signal obtained by electrical laboratory measurements with the CCC-XD are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK005
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WEPAL006	Experimental Study of a Differential Beam Intensity Monitoring for the CIADS LINAC	experiment, linac, monitoring, machine-protect	2155
	Z.P. Xie, Y.K. Ding, J. Liang Hohai University, Nanjing, People's Republic of China Y. He, Z.J. Wang, J.X. Wu, Y. Zhang IMP/CAS, Lanzhou, People's Republic of China
	Funding: Work supported by the National Natural Science Foundation of China (Grant No. 91026001) and the Fundamental Research Funds for the Chinese Central Universities A BPM based beam loss monitoring scheme for the China initiative accelerator driven subcritical (CIADS) facility has been proposed for the MEBT section of its high power Linac. In this scheme, a differential beam monitoring algorithm is utilized that relies on beam intensity measurements using BPM electrodes. Discussions of the experimental results for the scheme are presented. Further experiments have been performed with some promising results. This paper describes the experimental results with some analyses on measurement errors of the system. The proposed physical design of this system is described and further development is presented.
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WEPAL031	RF Interlock Implementation Using Digital LLRF System for 100 MeV Proton Linac at KOMAC	cavity, LLRF, controls, proton	2233
	H.S. Jeong, Y.-S. Cho, H.S. Kim, J.H. Kim, S.G. Kim, H.-J. Kwon, Y.G. Song Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea
	Funding: This work has been supported through KOMAC (Korea Multi-purpose Accelerator Complex) operation fund of KAERI by MSIT (Ministry of Science and ICT) KOMAC (Korea Multi-purpose Accelerator Complex) already has operated 100 MeV proton linear accelerator with high availability since 2013. This accelerator is composed of Ion source, LEBT, RFQ and DTL systems to transport proton particles to the target. Total 9 klystrons with 1.6 MWpeak are used to provide controlled RF power to the accelerator cavities with 350 MHz of operating frequency. These klystrons are driven by LLRF systems that the LLRF systems should control the RF and protect the amplifiers and cavities from the abnormal RF. In this article, the RF interlock using cavity pickup signal introduced. When the cavity pickup amplitude breaks away from the adjustable upper or lower limit window, the digital LLRF system interrupts the LLRF output. These implementations were conducted by upgrading the FPGA (Field Programmable Gate Array) logics of the existing digital LLRF system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL031
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WEPAL067	Number of Turn Measurements on the HIPA Cyclotrons at PSI	cyclotron, proton, operation, LabView	2334
	P.-A. Duperrex, A. Facchetti PSI, Villigen PSI, Switzerland
	The number of turns is an important parameter for the tuning of a cyclotron; it is even more important for high intensity machines such as the 1.4 MW High Intensity Proton Accelerator (HIPA) facility. Up to recently, the number of turns had to be measured using radial probes, which cannot be performed during user operation but only during beam development shifts. For user shifts, the estimate of the number of turns was based on the acceleration voltage measurements, with the inherent limited precision of RF measurements. A new scheme based on the time of flight (ToF) measurements has been deployed on the two cyclotrons of HIPA. It is based on the cross-correlation of fast sampled data from pickups located at the entrance and at the exit of the cyclotrons. For the first cyclotron, called Injector 2 (accelerating the beam from 870 keV to 72MeV), the beam had to be externally modulated whereas, for the Ring Cyclotron (72 MeV to 590 MeV), no external modulation was necessary. This paper will present the details of both implementations, their limitations and the quality of the results that can be obtained with the ToF techniques.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL067
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WEPAL069	Reentrant Cavity Resonator for Low Intensities Proton Beam Measurements	simulation, cavity, resonance, scattering	2341
	S. Srinivasan, P.-A. Duperrex PSI, Villigen PSI, Switzerland
	A non-interceptive beam current monitor has been developed to investigate the measurement possibilities of low-intensity beams down to 1 nA for proton therapy machines without the drawback of interceptive monitors. This works on the principle of a reentrant cavity resonator such that its fundamental mode resonance frequency of 145.7 MHz matches the second harmonic of the pulse repetition rate of the cyclotron beam i.e. 72.85 MHz. The Driven Modal analysis from the simulation tool ANSYS HFSS was used for parametric model development and to optimize design parameters such as e.g. the position of the inductively coupled pick-ups. A ceramic plate has been inserted in the resonator gap to relax the precision required during manufacturing. A test bench has been designed and constructed for the characterization tests of the prototype. Comparison of the simulated and the experimental scattering parameter from the test bench shows a good agreement.
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WEPAL073	Enhanced Bunch Monitoring by Interferometric Electro-Optic Methods	laser, proton, polarization, optics	2353
	S.M. Gibson, A. Arteche, A. Bosco Royal Holloway, University of London, Surrey, United Kingdom S.E. Bashforth, A. Bosco, S.M. Gibson JAI, Egham, Surrey, United Kingdom M. Krupa, T. Lefèvre CERN, Geneva, Switzerland
	Funding: We acknowledge funding by UK STFC grant ST/N001583/1, JAI at Royal Holloway University of London and CERN A prototype Electro-Optic Beam Position Monitor has been installed for tests* in the CERN SPS to develop the concept for high-bandwidth (6-12GHz) monitoring of crabbed-bunch rotation and intra-bunch instabilities at the High Luminosity LHC*. The technique relies on the ultrafast response of birefringent MgO:LiNO3 crystals to optically measure the intra-bunch transverse displacement of a passing relativistic bunch. This paper reports on recent developments, including a new interferometric electro-optic pick-up that was installed in the CERN SPS in September 2017; in first beam tests with nominal bunch charge, a corresponding interferometric signal has been observed. The interferometric arrangement has the advantages of being sensitive to the strongest polarisation coefficient of the crystal, and the phase offset of the interferometer is controllable by frequency scanning of the laser, which enables rapid optimisation of the working point. Novel concepts and bench tests for enhancements to the pick-up design are reviewed, together with prospects for sensitivity during the first crab-cavity beam tests at the CERN SPS in 2018. A. Arteche et al "First beam tests at the CERN SPS of an electro-optic beam position monitor for the HL-LHC" TUPCF23, IBIC 2017. ** HL-LHC TDR v0.1 doi.org/10.23731/CYRM-2017-004
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL073
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WEPMF045	Performance of the Prototype SRF Half-Wave-Resonators Tested at Cornell for the RAON Project	cavity, SRF, multipactoring, radiation	2468
	M. Ge, F. Furuta, T. Gruber, S.W. Hartman, M. Liepe, J.T. Maniscalco, T.I. O'Connell, P.J. Pamel, J. Sears, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA B.H. Choi, J. Joo, J.W. Kim, W.K. Kim, J. Lee, I. Shin IBS, Daejeon, Republic of Korea
	Two prototype superconducting half-wave-resonator (162.5 MHz and β=0.12) for the RAON project have been successfully tested at Cornell University. Detailed vertical performance testing included (1) test of the bare cavity without the helium tank, and (2) test of the dressed cavity with a helium tank. In this paper, we report on the development of the test infrastructure, test results, and performance data analysis, showing that the specifications for RAON were met.
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WEPML049	The Challenge to Measure nΩ Surface Resistance on SRF Samples	SRF, quadrupole, cavity, simulation	2812
	S. Keckert, T. Junginger, J. Knobloch, O. Kugeler HZB, Berlin, Germany T. Junginger Lancaster University, Lancaster, United Kingdom
	Systematic research on fundamental limits of superconducting materials for SRF applications and their intrinsic material properties relevant for use in an accelerator requires studies in a wide parameter space of temperature, RF field and frequency. The Quadrupole Resonator at HZB enables precision measurements on planar samples at temperatures of 1.8 K to >20 K, RF fields of up to 120 mT, and frequencies of 420 MHz, 850 MHz and 1285 MHz. In the past years the capabilities of the setup were studied intensively and developed further. Sources of systematic errors, such as microphonics or misalignment have been identified and eliminated. In this contribution the current status of the QPR and its systematic limitations are discussed.
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THPAF058	Experimental Characterisation of a Fast Instability Linked to Losses in the 16L2 Cryogenic Half-Cell in the CERN LHC	MMI, electron, operation, monitoring	3103
	B. Salvant, S. A. Antipov, G. Arduini, N. Biancacci, X. Buffat, L.R. Carver, P. Collier, A.A. Gorzawski, W. Höfle, G. Iadarola, G. Kotzian, A. Lechner, T.E. Levens, D. Mirarchi, E. Métral, G. Rumolo, D. Valuch CERN, Geneva, Switzerland L. Mether EPFL, Lausanne, Switzerland
	The operation during the summer months of the 2017 Run of the CERN LHC was plagued with fast beam losses that repeatedly occurred in the 16th arc half-cell at the left of IP2 as well as in the collimation insertion, leading to unwanted beam dumps. Transverse coherent oscillations were observed during this fast process. We detail here the experimental observations of coherent motion that al-lowed shedding light upon parts of the mechanism and identify the potential mitigations that were successfully implemented in the second half of the Run.
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THPAK057	Simulations of Optical Stochastic Cooling with ELEGANT	damping, undulator, kicker, radiation	3354
	M.B. Andorf, P. Piot Northern Illinois University, DeKalb, Illinois, USA V.A. Lebedev, V.A. Lebedev, P. Piot Fermilab, Batavia, Illinois, USA
	Fermilab is pursuing a proof-of-principle test of the Optical Stochastic Cooling (OSC) of 100 MeV electrons in the Integrable Optics Test Accelerator. In support of this we present simulations of horizontal damping with OSC. We find excellent agreement with theory on the amplitude dependent damping rates. Additionally particle tracking is used to confirm the necessity and effectiveness of sextupoles used to correct non-linear path lengthening in the OSC chicane.
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THPAL112	RF Matching Circuit for CANREB RFQ	rfq, TRIUMF, network, simulation	3902
	T. Au, B. Barquest, J.J. Keir, V. Zvyagintsev TRIUMF, Vancouver, Canada
	A RF matching circuit has been developed to provide two phase RF voltage of 1.2 kVpp at 3 MHz and 6 MHz for the CANREB RFQ structure with an equivalent capacitive load of 300 pF. The RF matching circuit utilizes pi-network with two phase transformer. Beyond RF drive the CANREB structure requires pulse DC bias with amplitude up to 500 V. Results of development and testing of RF matching circuit and filters are presented in this paper.
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THPAL115	The Design of 1.1 MW RF Dummy Load for the RF System of 520 MeV Cyclotron	simulation, cyclotron, TRIUMF, controls	3911
	N.V. Avreline, Y. Bylinskii, B. Jakovljevic, Y. Ma, V. Zvyagintsev TRIUMF, Vancouver, Canada
	The RF System of 520-MeV Cyclotron is operating at 23 MHz with 1 MW CW RF power. The RF dummy load is required to troubleshoot and tune the RF amplifier. The RF system is being constantly improved and the future goal is to increase cyclotron's beam current up to 400 μA, which requires increasing the RF amplifier's power. As a part of this goal, a new RF dummy load was designed.
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THPMF032	Preparation and Testing of the BERLinPro Gun 1.1 Cavity	cavity, gun, cathode, niobium	4117
	H.-W. Glock, J. Knobloch, A. Neumann, Y. Tamashevich HZB, Berlin, Germany
	Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of the Helmholtz Association For the BERLinPro energy recovery LINAC, HZB is developing a superconducting 1.4-cell electron gun, which, in its final version, is planned to be capable of CW 1.3 GHz operation with 77 pC/bunch. For this purpose a series of three superconducting cavities, denoted as Gun 1.0, Gun 1.1 (both designed for 6 mA) and Gun 2.0 (100 mA) is foreseen. Here the status of the Gun 1.1 cavity is described, including results of the recent vertical testing. Lessons learned from the production and preparation process are summarized, also in order to identify issues critical for the production of Gun 2.0.
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THPMK090	First RF Test Results of Two-Cavities Accelerating Cryomodule for ARIEL eLinac at TRIUMF	cavity, cryomodule, linac, TRIUMF	4512
	Y. Ma, Z.T. Ang, K. Fong, J.J. Keir, D. Kishi, D. Lang, R.E. Laxdal, R.R. Nagimov, B.S. Waraich, Z.Y. Yao, V. Zvyagintsev TRIUMF, Vancouver, Canada
	The Advanced Rare Isotope Laboratory (ARIEL) pro-ject requires a 50 MeV, 10 mA continuous-wave (CW) electron linear accelerator (e-Linac) as a driver accelera-tor. Now the stage of the 30MeV portion of the e-Linac is under commissioning which includes an injector cry-omodule(ICM) and the 1st accelerator cryomodules (ACM1) with two cavities configuration. A single 290kW klystron is used to feed the two ACM1 cavities in vector sum closed-loop control. In this paper the initial commis-sioning results of the ACM1 RF system will be present.
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THPML065	Preliminary Results of the Bunch Arrival-Time Monitor at SXFEL	electron, laser, FEL, cavity	4787
	J.G. Wang, B. Liu SINAP, Shanghai, People's Republic of China
	Based on an electro-optical intensity modulation detection scheme, a Bunch Arrival-time Monitor (BAM) is under study at Shanghai soft X-ray Free Electron Laser (SXFEL) to meet the high-resolution requirements of the measurement of bunch arrival time. The first BAM is installed and is being tested at the SXFEL upstream of the first short undulator (modulator) near the seed laser injection point. In this paper, we present the basic working principle, the design of the BAM system and report the preliminary test results.
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THPML068	Upgrade of Bunch Phase Monitor at SSRF Storage Ring	injection, SRF, storage-ring, experiment	4797
	Y.M. Zhou, Y.B. Leng, T. Wu, N. Zhang SSRF, Shanghai, People's Republic of China
	Beam instability is a serious problem for physics in beam diagnosis technology. With regard to the evaluation of longitudinal phase oscillations during the transient injection process, bunch-by-bunch phase measurement is a useful tool for studying the behavior of the refilled bunches. A new upgraded beam phase monitor system with 1.2GHz bandwidth PXI waveform digitizer has been developed at Shanghai synchrotron radiation source (SSRF). Bunch-by-bunch phase information, retrieved from button pickup signals, is calculated by the zero-crossing detection method with the best phase resolution of 0.4ps. The refilled bunches can be separated from the stored ones, and the longitudinal offset of each refilled bunch has been measured. Several groups of experiments have been performed to verify the repeatability of bunch-by-bunch phase measurement, and some results regarding refilled bunches will be discussed in this paper.
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THPML101	A Novel Double Sideband-Based Phase Averaging Line for Phase Reference Distribution System	LLRF, experiment, laser, FPGA	4901
	Z.Y. Lin, Y.-C. Du, W.-H. Huang, Z. Pan, C.-X. Tang, C.-X. Tang, Y.L. Xu, J. Yang TUB, Beijing, People's Republic of China G. Huang LBNL, Berkeley, California, USA
	Coaxial cable based solution is one of the most important scheme in Phase Reference Distribution System. A novel double sideband-based phase averaging line has been developed in Tsinghua accelerator lab. The sender chassis generates the 2856 MHz signal as the forward signal and receives the 2856 MHz signal and the reflected double sideband signal from the receiver. The forward signal is phase-locked with the reference signal, and the forward signal and the sideband signal are adjusted by the FPGA virtual delay line. The preliminary experiments result shows the phase stability can achieve about 1% by signal distorted by the phase shifter.
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Paper

Title

Other Keywords

Page

TUPAF011

Btrain Calibration with RF-Master Method

dipole, cavity, synchrotron, injection

679

L. Falbo, E. Bressi, M. Pezzetta, C. Priano
CNAO Foundation, Milan, Italy

CNAO is the only Italian hadrontherapy facility able to treat tumors with beams of protons and carbon ions. It is based on a synchrotron with a 77 m ring equipped with 16 normal conducting dipoles characterized by a long delay in the field stabilization. B-Train system is a fundamental device of the whole machine; it is used in feedback to the dipole power supply in order to regulate the magnetic field reducing the natural stabilization times that would cause long treatments. B-Train system allows to obtain the magnetic field starting from measurements of magnetic field changes: it works as an integrator and then it needs a system to reset the counts compensating the electronic and numerical drift of the system itself. An innovative method has been implemented at CNAO to reset Btrain counts exploiting beam measurements after the RF cavity trapping. This procedure has the advantage to avoid external and additional element like NMR probes. The paper shows the use of B-train system at CNAO and its calibration with this method, called "RF-master method".

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TUPAF036

Studies of the Injection and Cooling Efficiency in LEIR Using the Longitudinal Schottky Spectrum

injection, linac, diagnostics, electron

765

S. Hirlaender, R. Alemany-Fernández, H. Bartosik, N. Biancacci, V. Kain
CERN, Geneva, Switzerland

The CERN Low Energy Ion Ring (LEIR) has two main operational beams with their associated cycles, the so-called EARLY and the NOMINAL beam. The EARLY beam consists of a single injected pulse from the LINAC3 accelerator, whereas seven consecutive injections are accumulated, and electron cooled for the NOMINAL beam. In both cases, the longitudinal Schottky monitor allows assessing the longitudinal particle distribution during the cooling process on the injection plateau. A method has been established to analyze the Schottky signal, reconstruct the initial particle momentum distribution and derive relevant parameters such as the cooling time, energy off-set of injected and stacked beam or the momentum distribution of the lost beam. The variations of the obtained parameters and the impact on the LEIR performance will be addressed.

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TUPAF078

Recent Results of HESR Original Stochastic Cooling Tanks at COSY

kicker, experiment, storage-ring, hardware

913

R. Stassen, B. Breitkreutz, N. Shurkhno
FZJ, Jülich, Germany

The High Energy Storage Ring (HESR) of the FAIR project at GSI Darmstadt will be very important for different scientific programs due to the modularized start version of FAIR. Stochastic cooling together with barrier bucket operation will be the key component to fulfill the requirements of the different experiments. First pickup and first kicker of the HESR stochastic cooling system have been installed into the COSY accelerator at FZJ Jülich. COSY is well suited to test the performance of the HESR stochastic cooling hardware at different energies and variable particle numbers. The novel dedicated HESR-structures were already successfully tested at the Nuclotron in Dubna for longitudinal cooling and during a beam time 2017 for transverse cooling at COSY. The results of the last stochastic cooling beam time will be presented as well as the first use of GaN based amplifiers in a stochastic cooling system. The HESR needs fast transmission-lines between PU and KI. Beside air-filled coax-lines, optical hollow fiber-lines are very attractive. First results with such a hollow fiber used for the transverse signal path will be presented.

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TUPAF079

Scaled Alvarez-Cavity Model Investigations for the UNILAC Upgrade

DTL, cavity, simulation, alignment

916

M. Heilmann, X. Du, L. Groening, M. Kaiser, S. Mickat, M. Vossberg
GSI, Darmstadt, Germany
A. Seibel
IAP, Frankfurt am Main, Germany

The 1:3 scaled aluminum model of an Alvarez-type cavity with 10 gaps was used for comparison of simulation with measurement for the frequency and the electric field on axis. The scaled frequency is 325.224 MHz and an Alvarez cavity has a small frequency tuning range. With this scaled model it was possible to apply different stem configurations for each drift tube to damp parasitic modes and to increase the field stability. The new drift tubes have an optimized free-formed profile on the end plates in order to increase the shunt impedance. In special the assembly, positioning and alignment of the drift tubes can be tested and the frequency change can be investigated in this respect.

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TUPAL033

Time-of-Flight, Beam-Energy Measurement of the LANSCE 805-MHz Linac

linac, proton, controls, DTL

1075

Y.K. Batygin, F.E. Shelley, H.A. Watkins
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396.
Control of the beam-energy ramp along the length of a proton linear accelerator is required to keep the accelerator tuned according to design. Historically, the values of the field amplitudes and phases of the side-coupled, 805-MHz LANSCE linac modules are maintained using a well-known delta-t tuning procedure*. Time-of-flight measurements of the proton beam energy are now also being used to confirm and improve the overall control of the energy ramp along the linac. The time-of-flight method uses measurements of the difference in RF phases measured as the beam passes installed delta-t pickup loops. A newly developed chassis to control the 3D position of the beam centroid is used. Details of the procedure and results of measurements are presented.
* K.R.Crandall, "The Delta-T Tuneup Procedure for the LAMPF 805-MHz Linac", LANL Report LA-6374-MS, June 1976.

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TUPMF034

Measuring the Electrical Center and Field Flatness of 704 MHz Deflecting Cavity for LEReC with Wire Stretching System

cavity, simulation, diagnostics, experiment

1320

T. Xin, J.M. Brennan, J.C.B. Brutus, K. Mernick, K.S. Smith, B. P. Xiao, A. Zaltsman
BNL, Upton, Long Island, New York, USA
W. Johnson
SBU, Stony Brook, New York, USA
H. Wang
JLab, Newport News, Virginia, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
704 MHz deflecting cavity was designed for the Low Energy RHIC electron Cooling (LEReC) project. The cavity will serve as a major component in diagnostic line. In LEReC project the requirement on the energy spread of the electron beam is extremely high (better than 10^-4) and the diagnostic system has to to be designed accordingly. The 704 MHz transverse deflecting cavity provides the vertical kick to the beam after it passes through the dispersion dipole so that we can measure the energy spread of the core of the bunch. Traditional way of determining the electrical center of the cavity involves the needle pulling and integration of the signal which is prone to the cumulative error. We present the measurement result from a wire stretching system that is much more efficient and accurate compared to the bead/needle pulling method. Both simulation and experimental results are shown in this paper and the potential in further application is discussed at the end.

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WEPAF019

Fast Readout Algorithm for Cylindrical Beam Position Monitors Providing Good Accuracy for Particle Bunches with Large Offsets

simulation, FPGA, electron, collider

1864

P. Thieberger, D.M. Gassner, R.L. Hulsart, R.J. Michnoff, T.A. Miller, M.G. Minty, Z. Sorrell
BNL, Upton, Long Island, New York, USA
A.C. Bartnik
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, 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 simple, analytically correct algorithm is developed for calculating 'pencil' beam coordinates using the signals from an ideal cylindrical beam position monitor (BPM) with four pickup electrodes (PUEs) of infinitesimal widths. The algorithm is then applied to simulations of realistic BPMs with finite width PUEs. Surprisingly small deviations are found. Simple empirically determined correction terms reduce the deviations even further. Finally, the algorithm is used to study the impact of beam-size upon the precision of BPMs in the non-linear region. As an example of the data acquisition speed advantage, a FPGA-based BPM readout implementation of the new algorithm has been developed and characterized

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WEPAF024

Turn-by-Turn Position Measurements at CNAO with the Libera Spark HR Prototype

hadron, electronics, instrumentation, electron

1870

M. Cargnelutti, M. Žnidarčič
I-Tech, Solkan, Slovenia
G.M.A. Calvi, A. Parravicini, E. Rojatti, C. Viviani
CNAO Foundation, Milan, Italy

CNAO in Pavia is one of the first centers for hadrontherapy in Europe, treating patients since 2011. The center is an international reference for a whole new concept of machines being constructed for this purpose. The synchrotron BPM electronics is based on analog boards that compute the ratio between difference and sum signals from the shoebox pickup, later acquired by digital cards. Although the system operates reliably, it just calculates the position with 1kHz rate, while the revolution frequency ranges from 0.5 to 3 MHz. To extend the measurement possibilities for these new hadron synchrotrons, Instrumentation Technologies is developing a data acquisition system capable of acquiring the pickup signals with 125MSps ADCs and calculating bunchbybunch positions of the accelerated beam. The first prototype was tested at CNAO: the turnbyturn beam position was analyzed off line, at different energies and positions with both Protons and Carbon ions beam. This paper will presents the results achieved with the system and compares them with the measurements of the current system.

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WEPAF049

Energy Beam Position Monitor Button Array Electronics for the European XFEL

electron, FEL, vacuum, electronics

1927

B. Lorbeer, B. Beutner, H.T. Duhme, L. Fröhlich, D. Lipka, D. Nölle
DESY, Hamburg, Germany

The European XFEL(X-Ray Free Electron Laser) at DESY(Deutsches Elektronen-Synchrotron) in Hamburg/Schenefeld started commissioning in early 2017. Before the pulsed electron beam is accelerated to its final energy of 14 GeV, the energy of the bunch can be compressed in three bunch compression chicanes at 130 MeV, 700 MeV and 2400 MeV. The vacuum chamber in these sections is tapered from 40 mm round beam pipe to a 40 cm rectangular shaped vacuum section. A custom made button array type of BPM(Beam position Monitor) is installed in this section with 26 button electrode feed-throughs. The analog and digital readout electronics for this monitor and the first experience with the calibration and operational aspects of this system are presented in this poster.

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WEPAF059

A Low Cost Beam Position Monitor System

electron, electronics, hardware, target

1961

C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
J.G. Power, J.H. Shao
ANL, Argonne, Illinois, USA
C. Yin
University of Chicago, Chicago, Illinois, USA

A Beam Position Monitor (BPM) system is essential to beam diagnostics for almost all particle accelerators. However, a typical BPM system contains customized hardware and complicated processing electronics which considerably drive the cost for large facilities where hundreds of them may be used. It also limits its use in the small scale accelerator facilities. In the paper, we present a low cost BPM system which consists of a commercial available CF flange based signal pickup device, a low cost integrated circuit adjacent to the pickup to filter, sample, digitize, and broadcast the signals out of the pickup electrodes. The digital signal is transmitted out for post processing through noise-protected Wi-Fi router. We will briefly discuss the working principle and experimental progress to date.

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WEPAF080

Beam Size Measurements Based on Movable Quadrupolar Pick-ups

emittance, alignment, embedded, quadrupole

2028

A. Sounas, M. Gąsior, T. Lefèvre, A. Mereghetti, J. Olexa, S. Redaelli, G. Valentino
CERN, Geneva, Switzerland

Measurements with quadrupolar pick-ups (PU) have attracted particular interest as non-intercepting diagnostics for determining the transverse beam size. They are based on processing the signals of an electromagnetic PU for the extraction of the second-order moment, which contains information about the beam size. Despite the simplicity of the concept, quadrupololar measurements have always been highly challenging in reality. This comes from the fact that the quadrupolar moment constitutes only a very small part of the total PU signal dominated by the intensity and the position signals. Therefore, the beam size information can easily be lost due to small imperfections in the signal processing chain, such as asymmetries in the electronics and cables. In this paper, we present a new method for quadrupolar measurements using movable PUs. Through position and aperture scans, our technique minimizes the parasitic beam position signal and takes into account imperfections of the PU, cables and electronics, thus enabling an efficient auto-calibration of the measurement system. Preliminary studies, using collimators with embedded electrostatic PUs in the LHC at CERN, have shown very promising results.

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WEPAF085

Upgrade of the CERN SPS Beam Position Measurement System

electron, electronics, proton, FPGA

2047

M. Wendt, M. Barros Marin, A. Boccardi, T.B. Bogey, V. Kain, C. Moran Guizan, A. Topaloudis
CERN, Geneva, Switzerland
I. Degl'Innocenti
Università di Pisa, Pisa, Italy

The CERN Super Proton Synchrotron (SPS) is a fast cycling hadron accelerator delivering protons with momenta of up to 450 GeV/c for the Large Hadron Collider (LHC), fixed target experiments and other users such as the AWAKE plasma acceleration experiment, and also used to accelerate heavy ions. This paper presents the upgrade initiative for the SPS beam position measurement system in the frame of the CERN LHC Injector Upgrade (LIU) project. The new SPS beam position read-out electronics will be based on logarithmic amplifiers, using signals provided by the 216 existing beam position monitors, the majority of which are based on split-plane 'shoebox' technology. It will need to cover a dynamic range sufficient to manage the wide range of SPS beam intensities and bunch formatting schemes to provide turn-by-turn and averaged beam orbits along the SPS acceleration cycles. In order to avoid long coaxial cables, the front-end electronics including the digitisation, will be located inside the accelerator tunnel, with optical transmission to surface processing electronics. This represents an additional challenge in terms of radiation tolerance of electronics components and materials.

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WEPAK005

A Cryogenic Current Comparators (CCC) Customized for FAIR-Project

niobium, shielding, cryogenics, electronics

2088

J. Golm, R. Neubert, F. Schmidl, P. Seidel
FSU Jena, Jena, Germany
J. Golm, T. Stöhlker, V. Tympel
HIJ, Jena, Germany
D.M. Haider, F. Kurian, M. Schwickert, T. Sieber, T. Stöhlker
GSI, Darmstadt, Germany
R. Neubert
Thuringia Observatory Tautenburg, Tautenburg, Germany
M. Schmelz, R. Stolz
IPHT, Jena, Germany
T. Stöhlker
IOQ, Jena, Germany
V. Zakosarenko
Supracon AG, Jena, Germany

The principle of non-destructive measurement of ion beams by detection of the azimuthal magnetic field, using low temperature Superconducting Quantum Interference Device (SQUID) sensors, has been established at GSI already in the mid 90's. After more recent developments at Jena, GSI and CERN, a CCC was installed in the CERN Antiproton Decelerator (AD) and is operated there routinely as the first stand-alone CCC system. For the Facility for Antiproton and Ion Research (FAIR) a new version of the CCC with eXtended Dimensions (CCC-XD) - especially with a larger inner diameter and adapted parameters - was constructed and first lab tests have already been performed. In parallel, a concept for a dedicated UHV beamline cryostat has been worked out. The CCC-XD system - together with the new cryostat - will be ready for testing in the CRYRING at GSI before the end of 2018. In this contribution, experimental results for the resolution, frequency range, slew rate and pulse-signal obtained by electrical laboratory measurements with the CCC-XD are presented.

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WEPAL006

Experimental Study of a Differential Beam Intensity Monitoring for the CIADS LINAC

experiment, linac, monitoring, machine-protect

2155

Z.P. Xie, Y.K. Ding, J. Liang
Hohai University, Nanjing, People's Republic of China
Y. He, Z.J. Wang, J.X. Wu, Y. Zhang
IMP/CAS, Lanzhou, People's Republic of China

Funding: Work supported by the National Natural Science Foundation of China (Grant No. 91026001) and the Fundamental Research Funds for the Chinese Central Universities
A BPM based beam loss monitoring scheme for the China initiative accelerator driven subcritical (CIADS) facility has been proposed for the MEBT section of its high power Linac. In this scheme, a differential beam monitoring algorithm is utilized that relies on beam intensity measurements using BPM electrodes. Discussions of the experimental results for the scheme are presented. Further experiments have been performed with some promising results. This paper describes the experimental results with some analyses on measurement errors of the system. The proposed physical design of this system is described and further development is presented.

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WEPAL031

RF Interlock Implementation Using Digital LLRF System for 100 MeV Proton Linac at KOMAC

cavity, LLRF, controls, proton

2233

H.S. Jeong, Y.-S. Cho, H.S. Kim, J.H. Kim, S.G. Kim, H.-J. Kwon, Y.G. Song
Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea

Funding: This work has been supported through KOMAC (Korea Multi-purpose Accelerator Complex) operation fund of KAERI by MSIT (Ministry of Science and ICT)
KOMAC (Korea Multi-purpose Accelerator Complex) already has operated 100 MeV proton linear accelerator with high availability since 2013. This accelerator is composed of Ion source, LEBT, RFQ and DTL systems to transport proton particles to the target. Total 9 klystrons with 1.6 MWpeak are used to provide controlled RF power to the accelerator cavities with 350 MHz of operating frequency. These klystrons are driven by LLRF systems that the LLRF systems should control the RF and protect the amplifiers and cavities from the abnormal RF. In this article, the RF interlock using cavity pickup signal introduced. When the cavity pickup amplitude breaks away from the adjustable upper or lower limit window, the digital LLRF system interrupts the LLRF output. These implementations were conducted by upgrading the FPGA (Field Programmable Gate Array) logics of the existing digital LLRF system.

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WEPAL067

Number of Turn Measurements on the HIPA Cyclotrons at PSI

cyclotron, proton, operation, LabView

2334

P.-A. Duperrex, A. Facchetti
PSI, Villigen PSI, Switzerland

The number of turns is an important parameter for the tuning of a cyclotron; it is even more important for high intensity machines such as the 1.4 MW High Intensity Proton Accelerator (HIPA) facility. Up to recently, the number of turns had to be measured using radial probes, which cannot be performed during user operation but only during beam development shifts. For user shifts, the estimate of the number of turns was based on the acceleration voltage measurements, with the inherent limited precision of RF measurements. A new scheme based on the time of flight (ToF) measurements has been deployed on the two cyclotrons of HIPA. It is based on the cross-correlation of fast sampled data from pickups located at the entrance and at the exit of the cyclotrons. For the first cyclotron, called Injector 2 (accelerating the beam from 870 keV to 72MeV), the beam had to be externally modulated whereas, for the Ring Cyclotron (72 MeV to 590 MeV), no external modulation was necessary. This paper will present the details of both implementations, their limitations and the quality of the results that can be obtained with the ToF techniques.

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WEPAL069

Reentrant Cavity Resonator for Low Intensities Proton Beam Measurements

simulation, cavity, resonance, scattering

2341

S. Srinivasan, P.-A. Duperrex
PSI, Villigen PSI, Switzerland

A non-interceptive beam current monitor has been developed to investigate the measurement possibilities of low-intensity beams down to 1 nA for proton therapy machines without the drawback of interceptive monitors. This works on the principle of a reentrant cavity resonator such that its fundamental mode resonance frequency of 145.7 MHz matches the second harmonic of the pulse repetition rate of the cyclotron beam i.e. 72.85 MHz. The Driven Modal analysis from the simulation tool ANSYS HFSS was used for parametric model development and to optimize design parameters such as e.g. the position of the inductively coupled pick-ups. A ceramic plate has been inserted in the resonator gap to relax the precision required during manufacturing. A test bench has been designed and constructed for the characterization tests of the prototype. Comparison of the simulated and the experimental scattering parameter from the test bench shows a good agreement.

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WEPAL073

Enhanced Bunch Monitoring by Interferometric Electro-Optic Methods

laser, proton, polarization, optics

2353

S.M. Gibson, A. Arteche, A. Bosco
Royal Holloway, University of London, Surrey, United Kingdom
S.E. Bashforth, A. Bosco, S.M. Gibson
JAI, Egham, Surrey, United Kingdom
M. Krupa, T. Lefèvre
CERN, Geneva, Switzerland

Funding: We acknowledge funding by UK STFC grant ST/N001583/1, JAI at Royal Holloway University of London and CERN
A prototype Electro-Optic Beam Position Monitor has been installed for tests* in the CERN SPS to develop the concept for high-bandwidth (6-12GHz) monitoring of crabbed-bunch rotation and intra-bunch instabilities at the High Luminosity LHC**. The technique relies on the ultrafast response of birefringent MgO:LiNO3 crystals to optically measure the intra-bunch transverse displacement of a passing relativistic bunch. This paper reports on recent developments, including a new interferometric electro-optic pick-up that was installed in the CERN SPS in September 2017; in first beam tests with nominal bunch charge, a corresponding interferometric signal has been observed. The interferometric arrangement has the advantages of being sensitive to the strongest polarisation coefficient of the crystal, and the phase offset of the interferometer is controllable by frequency scanning of the laser, which enables rapid optimisation of the working point. Novel concepts and bench tests for enhancements to the pick-up design are reviewed, together with prospects for sensitivity during the first crab-cavity beam tests at the CERN SPS in 2018.
* A. Arteche et al "First beam tests at the CERN SPS of an electro-optic beam position monitor for the HL-LHC" TUPCF23, IBIC 2017.
** HL-LHC TDR v0.1 doi.org/10.23731/CYRM-2017-004

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WEPMF045

Performance of the Prototype SRF Half-Wave-Resonators Tested at Cornell for the RAON Project

cavity, SRF, multipactoring, radiation

2468

M. Ge, F. Furuta, T. Gruber, S.W. Hartman, M. Liepe, J.T. Maniscalco, T.I. O'Connell, P.J. Pamel, J. Sears, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
B.H. Choi, J. Joo, J.W. Kim, W.K. Kim, J. Lee, I. Shin
IBS, Daejeon, Republic of Korea

Two prototype superconducting half-wave-resonator (162.5 MHz and β=0.12) for the RAON project have been successfully tested at Cornell University. Detailed vertical performance testing included (1) test of the bare cavity without the helium tank, and (2) test of the dressed cavity with a helium tank. In this paper, we report on the development of the test infrastructure, test results, and performance data analysis, showing that the specifications for RAON were met.

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WEPML049

The Challenge to Measure nΩ Surface Resistance on SRF Samples

SRF, quadrupole, cavity, simulation

2812

S. Keckert, T. Junginger, J. Knobloch, O. Kugeler
HZB, Berlin, Germany
T. Junginger
Lancaster University, Lancaster, United Kingdom

Systematic research on fundamental limits of superconducting materials for SRF applications and their intrinsic material properties relevant for use in an accelerator requires studies in a wide parameter space of temperature, RF field and frequency. The Quadrupole Resonator at HZB enables precision measurements on planar samples at temperatures of 1.8 K to >20 K, RF fields of up to 120 mT, and frequencies of 420 MHz, 850 MHz and 1285 MHz. In the past years the capabilities of the setup were studied intensively and developed further. Sources of systematic errors, such as microphonics or misalignment have been identified and eliminated. In this contribution the current status of the QPR and its systematic limitations are discussed.

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THPAF058

Experimental Characterisation of a Fast Instability Linked to Losses in the 16L2 Cryogenic Half-Cell in the CERN LHC

MMI, electron, operation, monitoring

3103

B. Salvant, S. A. Antipov, G. Arduini, N. Biancacci, X. Buffat, L.R. Carver, P. Collier, A.A. Gorzawski, W. Höfle, G. Iadarola, G. Kotzian, A. Lechner, T.E. Levens, D. Mirarchi, E. Métral, G. Rumolo, D. Valuch
CERN, Geneva, Switzerland
L. Mether
EPFL, Lausanne, Switzerland

The operation during the summer months of the 2017 Run of the CERN LHC was plagued with fast beam losses that repeatedly occurred in the 16th arc half-cell at the left of IP2 as well as in the collimation insertion, leading to unwanted beam dumps. Transverse coherent oscillations were observed during this fast process. We detail here the experimental observations of coherent motion that al-lowed shedding light upon parts of the mechanism and identify the potential mitigations that were successfully implemented in the second half of the Run.

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THPAK057

Simulations of Optical Stochastic Cooling with ELEGANT

damping, undulator, kicker, radiation

3354

M.B. Andorf, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
V.A. Lebedev, V.A. Lebedev, P. Piot
Fermilab, Batavia, Illinois, USA

Fermilab is pursuing a proof-of-principle test of the Optical Stochastic Cooling (OSC) of 100 MeV electrons in the Integrable Optics Test Accelerator. In support of this we present simulations of horizontal damping with OSC. We find excellent agreement with theory on the amplitude dependent damping rates. Additionally particle tracking is used to confirm the necessity and effectiveness of sextupoles used to correct non-linear path lengthening in the OSC chicane.

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THPAL112

RF Matching Circuit for CANREB RFQ

rfq, TRIUMF, network, simulation

3902

T. Au, B. Barquest, J.J. Keir, V. Zvyagintsev
TRIUMF, Vancouver, Canada

A RF matching circuit has been developed to provide two phase RF voltage of 1.2 kVpp at 3 MHz and 6 MHz for the CANREB RFQ structure with an equivalent capacitive load of 300 pF. The RF matching circuit utilizes pi-network with two phase transformer. Beyond RF drive the CANREB structure requires pulse DC bias with amplitude up to 500 V. Results of development and testing of RF matching circuit and filters are presented in this paper.

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THPAL115

The Design of 1.1 MW RF Dummy Load for the RF System of 520 MeV Cyclotron

simulation, cyclotron, TRIUMF, controls

3911

N.V. Avreline, Y. Bylinskii, B. Jakovljevic, Y. Ma, V. Zvyagintsev
TRIUMF, Vancouver, Canada

The RF System of 520-MeV Cyclotron is operating at 23 MHz with 1 MW CW RF power. The RF dummy load is required to troubleshoot and tune the RF amplifier. The RF system is being constantly improved and the future goal is to increase cyclotron's beam current up to 400 μA, which requires increasing the RF amplifier's power. As a part of this goal, a new RF dummy load was designed.

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THPMF032

Preparation and Testing of the BERLinPro Gun 1.1 Cavity

cavity, gun, cathode, niobium

4117

H.-W. Glock, J. Knobloch, A. Neumann, Y. Tamashevich
HZB, Berlin, Germany

Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of the Helmholtz Association
For the BERLinPro energy recovery LINAC, HZB is developing a superconducting 1.4-cell electron gun, which, in its final version, is planned to be capable of CW 1.3 GHz operation with 77 pC/bunch. For this purpose a series of three superconducting cavities, denoted as Gun 1.0, Gun 1.1 (both designed for 6 mA) and Gun 2.0 (100 mA) is foreseen. Here the status of the Gun 1.1 cavity is described, including results of the recent vertical testing. Lessons learned from the production and preparation process are summarized, also in order to identify issues critical for the production of Gun 2.0.

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THPMK090

First RF Test Results of Two-Cavities Accelerating Cryomodule for ARIEL eLinac at TRIUMF

cavity, cryomodule, linac, TRIUMF

4512

Y. Ma, Z.T. Ang, K. Fong, J.J. Keir, D. Kishi, D. Lang, R.E. Laxdal, R.R. Nagimov, B.S. Waraich, Z.Y. Yao, V. Zvyagintsev
TRIUMF, Vancouver, Canada

The Advanced Rare Isotope Laboratory (ARIEL) pro-ject requires a 50 MeV, 10 mA continuous-wave (CW) electron linear accelerator (e-Linac) as a driver accelera-tor. Now the stage of the 30MeV portion of the e-Linac is under commissioning which includes an injector cry-omodule(ICM) and the 1st accelerator cryomodules (ACM1) with two cavities configuration. A single 290kW klystron is used to feed the two ACM1 cavities in vector sum closed-loop control. In this paper the initial commis-sioning results of the ACM1 RF system will be present.

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THPML065

Preliminary Results of the Bunch Arrival-Time Monitor at SXFEL

electron, laser, FEL, cavity

4787

J.G. Wang, B. Liu
SINAP, Shanghai, People's Republic of China

Based on an electro-optical intensity modulation detection scheme, a Bunch Arrival-time Monitor (BAM) is under study at Shanghai soft X-ray Free Electron Laser (SXFEL) to meet the high-resolution requirements of the measurement of bunch arrival time. The first BAM is installed and is being tested at the SXFEL upstream of the first short undulator (modulator) near the seed laser injection point. In this paper, we present the basic working principle, the design of the BAM system and report the preliminary test results.

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THPML068

Upgrade of Bunch Phase Monitor at SSRF Storage Ring

injection, SRF, storage-ring, experiment

4797

Y.M. Zhou, Y.B. Leng, T. Wu, N. Zhang
SSRF, Shanghai, People's Republic of China

Beam instability is a serious problem for physics in beam diagnosis technology. With regard to the evaluation of longitudinal phase oscillations during the transient injection process, bunch-by-bunch phase measurement is a useful tool for studying the behavior of the refilled bunches. A new upgraded beam phase monitor system with 1.2GHz bandwidth PXI waveform digitizer has been developed at Shanghai synchrotron radiation source (SSRF). Bunch-by-bunch phase information, retrieved from button pickup signals, is calculated by the zero-crossing detection method with the best phase resolution of 0.4ps. The refilled bunches can be separated from the stored ones, and the longitudinal offset of each refilled bunch has been measured. Several groups of experiments have been performed to verify the repeatability of bunch-by-bunch phase measurement, and some results regarding refilled bunches will be discussed in this paper.

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THPML101

A Novel Double Sideband-Based Phase Averaging Line for Phase Reference Distribution System

LLRF, experiment, laser, FPGA

4901

Z.Y. Lin, Y.-C. Du, W.-H. Huang, Z. Pan, C.-X. Tang, C.-X. Tang, Y.L. Xu, J. Yang
TUB, Beijing, People's Republic of China
G. Huang
LBNL, Berkeley, California, USA

Coaxial cable based solution is one of the most important scheme in Phase Reference Distribution System. A novel double sideband-based phase averaging line has been developed in Tsinghua accelerator lab. The sender chassis generates the 2856 MHz signal as the forward signal and receives the 2856 MHz signal and the reflected double sideband signal from the receiver. The forward signal is phase-locked with the reference signal, and the forward signal and the sideband signal are adjusted by the FPGA virtual delay line. The preliminary experiments result shows the phase stability can achieve about 1% by signal distorted by the phase shifter.

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