SUSPL —  Student Poster Session   (29-Apr-18   14:00—18:00)
Chair: O.K. Kester, TRIUMF, Vancouver, Canada
Paper Title Page
SUSPL049
 Simulating Non-Relativistic Beams Using Helical Pulse Lines  
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  • 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. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL049  
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SUSPL050
 Development of a Gas Sheet Beam Profile Monitor for IOTA  
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  • S. Szustkowski, B.T. Freemire
    Northern Illinois University, DeKalb, Illinois, USA
  • S. Chattopadhyay
    Northern Illinois Univerity, DeKalb, Illinois, USA
  • D.J. Crawford
    Fermilab, Batavia, Illinois, USA
  
  Funding: US Department of Energy, Office of High Energy Physics, General Accelerator Research and Development (GARD) Program
A nitrogen gas sheet will measure the two dimensional transverse profile of the 2.5 MeV proton beam in IOTA. The beam lifetime is limited by the interaction with the gas, thus a minimally invasive instrument is required. To produce a gas sheet with the desired density and thickness, various nozzle types are being investigated, including rectangular capillary tubes for gas injection and skimmers for final shaping of the gas. It is essential to meet vacuum requirements in the interaction chamber while maintaining the precise thickness and density of the gas, without significantly affecting the beam lifetime. The current design of a gas sheet beam profile monitor and present status will be discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL065  
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SUSPL051
 Development of Real-Time Mass Analysis System with Permanent Magnet for Ion Beam  
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  • Y. Takeuchi, Y. Iwashita, H. Tongu
    Kyoto ICR, Uji, Kyoto, Japan
  
  In order to analyze time variation of the ion species in a pulse, we are developing a mass analysis system that has multiple collector electrodes to detect several ion species simultaneously. Strong permanent magnets can generate 1T magnetic field and the size of the analyzing magnet system can be compact. The detected signals are scanned by a fast multiplexer. The scanning rate is 2 MHz, so that all electrode signals of the 16 channels are scanned in 8 μs period. In this paper, details of the design of the analysis system, and preliminary beam extraction test results with prototype of the system are described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL033  
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SUSPL052
 Beam Induced Fluorescence Measurements of 100 keV Deuterons in LIPAc Accelerator  
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  • R. Varela, A. Guirao, L.M. Martínez, J. Mollá, I. Podadera
    CIEMAT, Madrid, Spain
  • T. Akagi, R. Ichimiya, Y. Ikeda, M. Sugimoto
    QST, Aomori, Japan
  • B. Bolzon, N. Chauvin
    CEA/IRFU, Gif-sur-Yvette, France
  • P. Cara
    Fusion for Energy, Garching, Germany
  • H. Dzitko
    F4E, Germany
  • J. Knaster
    IFMIF/EVEDA, Rokkasho, Japan
  
  Funding: Work partially supported by the Spanish Ministry of Science and Innovation under project FIS2013-40860-R
The LIPAc accelerator will be a linear CW deuteron accelerator capable of delivering a 9 MeV, 125 mA beam which aims to validate the technology that will be used in the future high power accelerator-driven neutron source, IFMIF. In summer 2017 a campaign of measurements was done during the injector commissioning, in which a Fluorescence Profile Monitor based on an Intensified CID camera (ICID) was used to measure the beam transverse profile at the extraction of the ion source. In this contribution we review the design of the ICID, its performance and discuss the measurements carried out. The performance of ICID monitors for its use in future accelerators will be assessed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF026  
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SUSPL053
 Steering Optimizations for the University of Maryland Electron Ring  
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  • L. Dovlatyan, B.L. Beaudoin, R.A. Kishek, K.J. Ruisard
    UMD, College Park, Maryland, USA
  
  Funding: This work is supported by the US Dept. of Energy, Office of High Energy Physics award # DE-SC0010301
The University of Maryland Electron Ring (UMER) has the flexibility to set up alternative lattices for different research experiments, including nonlinear optics studies using octupoles. Each alternative lattice requires an acceptable steering solution for use in experiments. Existing beam-based alignment tools can take a significant amount of time to run and become difficult to process with a low number of BPMs. The Robust Conjugate Directional Search (RCDS) optimizer* is used to quickly obtain steering solutions for different lattice configurations and has been adopted for beam steering at UMER. Steering magnets are optimized online to reduce scraping, correct equilibrium orbits, and increase beam lifetimes. This study presents the application of the optimizer at UMER.
* X. Huang, J. Corbett, J. Safranek, J. Wu, Nucl. Instr. Meth. A vol. 726, pp. 77-83, 2013. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML107  
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SUSPL055
 Distributed I/O System Based on Ethernet POWERLINK Under the EPICS Architecture  
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  • X.K. Sun, G. Liu, Y. Song
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  Ethernet POWERLINK (EPL) is a communication profile for Real-Time Ethernet. The communication profile meets real-time demands for the distributed system composed of multiple controllers. EPICS is a wildly used distributed control system in large scientific facilities. We design a distributed IO system based on EPL under the EPICS architecture and establish the prototype system composed of a PC and six FPGA boards. In this system, an EPICS driver based on openPOWERLINK is developed to monitor the system status. In this paper, the communication mechanism of EPL, the design of system architecture, the implementation of EPICS driver and the test results of prototype system will be described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML108  
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SUSPL056
 High Precision Beam Parameter Stabilization for P2 at MESA  
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  • R.F.K. Kempf, J. Diefenbach
    IKP, Mainz, Germany
  • K. Aulenbacher
    HIM, Mainz, Germany
  
  Funding: Cluster of Excellence PRISMA (EXC 1098/2014) German Research Foundation DFG (GRK 2128)
The experiment P2 will measure the weak mixing angle with an all-time high precision via electron-proton scattering. The measured physics asymmetry and its uncertainty has to be corrected by the apparatus' asymmetry, which is generated by helicity correlated fluctuations of the beam parameters position, angle, intensity and energy. This Poster will describe how the high precision of 0.1 ppb of the parity violating asymmetry can be provided by the high precision measurements of the parameters position, angle and intensity. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL024  
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SUSPL057
 Effect of Model Errors on the Closed Orbit Correction at the SIS18 Synchrotron of GSI  
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  • S.H. Mirza, P. Forck, H. Klingbeil, R. Singhpresenter
    GSI, Darmstadt, Germany
  • H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
  
  Funding: Deutscher Akademischer Austauschdienst under contract No. 91605207
A fast closed orbit feedback system (bandwidth in the order of 1 kHz) is under development at the GSI SIS18 synchrotron for the orbit correction from injection to extraction including the acceleration ramp. The static process model, represented as the orbit response matrix (ORM), is subjected to the systematic optics changes during ramp e.g. beta function and phase advance variations at the locations of BPMs and steerers. In addition to these systematic variations, model mismatches may arise from dipole and quadrupole magnet errors, space charge dependent tune shift as well as BPM and steerer calibration errors. In this contribution, the effects of these model errors on the closed orbit correction are investigated which is necessary for the robust stability analysis of the feedback controller. For the robustness tests, the traditional SVD-based matrix pseudo-inversion is compared to a Fourier-based analysis. The results are achieved by detailed simulations in MADX. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK003  
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SUSPL058
 Development of a Low-Latency, High-Precision, Beam-Based Feedback System Based on Cavity BPMs at the KEK ATF2  
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  • R.L. Ramjiawan, D.R. Bett, N. Blaskovic Kraljevic, R.M. Bodenstein, T. Bromwich, P. Burrows, G.B. Christian, C. Perry
    JAI, Oxford, United Kingdom
  
  A low-latency, intra-train feedback system employing cavity beam position monitors (BPMs) has been developed and tested at the Accelerator Test Facility (ATF2) at KEK. The feedback system can be operated with either position information from a single BPM to provide local beam stabilisation, or by using position information from two BPMs to stabilise the beam at an intermediate location. The correction is implemented using a stripline kicker and a custom power amplifier, with the feedback calculations being performed on a digital board built around a Field Programmable Gate Array (FPGA). The addition of indium sealing to the BPMs to increase the cavities' Q-values has led to improvements to the BPM system resolution, with current measurements of the resolution of order 20 nm. The feedback performance was tested with beam trains of two bunches, separated by 280 ns and with a charge of ~1 nC. For single- (two-)BPM feedback, stabilisation of the beam has been demonstrated to below 50 nm (41 nm). Ongoing work to improve the feedback performance further will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL025  
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SUSPL059
 Design of Control System for Dual-Head Radiation Therapy  
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  • H.S. Kim, J.-S. Chai, M. Ghergherehchi, D.H. Ha, J.C. Lee, H. Namgoong, J.H. Seo, Shin, S.W. Shin
    SKKU, Suwon, Republic of Korea
  • D. Lipka
    DESY, Hamburg, Germany
  
  Sungkyunkwan University groups have been developed advanced radiation therapy machine named dual-head radiation therapy gantry for reducing the treatment time by up to 30%. The main difference between previous radiation therapy machine is using two electron LINAC as X-ray sources at radiation therapy. In support of this system, control system based on SCADA and hardware development was implemented. The control system consists of supervisory computers and local controllers and the control network was ethernet and software was written by labVIEW. An overview of this control system is presented in paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML076  
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SUSPL060
 Phase Extraction and Stabilization for Coherent Pulse Stacking  
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  • Y.L. Xu, W.-H. Huang, C.-X. Tang, L.X. Yan
    TUB, Beijing, People's Republic of China
  • L.R. Doolittle, Q. Du, G. Huang, W. Leemans, D. Li, R.B. Wilcox, Y. Yang, T. Zhou
    LBNL, Berkeley, California, USA
  • A. Galvanauskas
    University of Michigan, Ann Arbor, Michigan, USA
  
  Funding: This work was supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under Contract DE-AC02-05CH11231.
Coherent pulse stacking (CPS) is a new time-domain coherent addition technique that stacks several optical pulses into a single output pulse, enabling high pulse energy and high average power. We model the CPS as a digital filter in the Z domain, and implement two deterministic algorithms extracting the cavity phase from limited data where only the pulse intensity is available. In a 2-stage 15-pulse CPS system, each optical cavity is stabilized at an individually-prescribed round-trip phase with 0.7 deg and 2.1 deg RMS phase errors for Stage 1 and Stage 2 respectively. Optical cavity phase control with nm accuracy ensures 1.2% intensity stability of the stacked pulse over 12 hours. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML099  
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SUSPL061
 Compensation of Transient Beam Loading in Ramping Synchrotrons Using a Fixed Frequency Processing Clock  
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  • F.J. Galindo Guarch, J.M.M.A. Moreno Arostegui
    Universitat Politécnica de Catalunya, Barcelona, Spain
  • P. Baudrenghien, F.J. Galindo Guarch
    CERN, Geneva, Switzerland
  
  Transient beam loading compensation schemes, such as One-Turn-FeedBack (OTFB), require beam synchronous processing (BSP). Swept clocks derived from the RF, and therefore harmonic to the revolution frequency, are widely used in CERN synchrotrons; this simplifies implementation with energy ramping, where the revolution frequency changes. It is however not optimal for state-of-the-art digital hardware that prefers fixed frequency clocks. An alternative to the swept clocking is the use of a deterministic protocol, for example, White Rabbit (WR): a fixed reference clock can be extracted from its data stream, while enabling digital distribution of the RF frequency among other data. New algorithms must be developed for BSP using this fixed clock and the digital data transmitted on the WR link. This is the strategy adopted for the SPS Low Level RF (LLRF) upgrade. The paper gives an overview of the technical, technological and historical motivations for such a paradigm evolution. It lists the problems of fixed clock BSP, and presents an innovative solution based on a real-time variable ratio re-sampler for implementing an OTFB with the new fixed clock scheme.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML121  
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SUSPL062
 A High Voltage Feedforward Subsystem of Low Level RF System for the High Power RF System  
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  • Z.Y. Lin, Y. C. Du, H.Q. Fengpresenter, W.-H. Huang, CY. Song, C.-X. Tang, Y.L. Xu, J. Yang
    TUB, Beijing, People's Republic of China
  • G. Huang
    LBNL, Berkeley, California, USA
  
  The Low Level Radio Frequency control (LLRF) system measures the RF signals from the accelerator tube, compares it with the phase reference received from the timing distribution system, and provides the drive signal to the high power RF system to provide synchronized RF voltage to the electron beam. Usually, the LLRF system can achieve a ~50 fs RMS phase jitter which is limited by the microwave devices. The phase noise arise from the high voltage variation of the high power system will significantly increase phase noise from low level RF signal to high power RF. A high voltage feed forward subsystem is proposed to deal with the phase noise caused by the high voltage jitter of the modulator. The demo system is depolyed in Thomson scattering X-ray source (TTX).and the primary experiment result anaylse is discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML100  
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SUSPL063
 Measurement of the RF Reference Phase Stability in the SuperKEKB Injector LINAC  
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  • N. Liu
    Sokendai, Ibaraki, Japan
  • D.A. Arakawa, H. Katagiri, T. Matsumoto, S. Michizono, T. Miura, F. Qiu, Y. Yano
    KEK, Ibaraki, Japan
  
  The SuperKEKB injector is a more than 600 m J-shaped LINAC. The requirement of the RF phase refer-ence stability is 0.1 degree (RMS) at 2856 MHz for SuperKEKB PHASE-2 commissioning. In order to clari-fy and improve the reference line performance, the RF reference phase stability is measured. The phase noise of the RF reference at each sector is shown in this paper. A new phase monitor system is implemented to measure the short-term stability and long-term drift due to the temperature and humidity fluctuations in the klystron gallery.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML073  
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SUSPL064
 Use of Dimension-Reduction Techniques With Multi-Objective Genetic Algorithms to Improve the Vertical Emittance and Orbit at CESR  
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  • W.F. Bergan, I.V. Bazarov, C.J. Duncan, D. L. Rubin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • D. Liarte, J.P. Sethna
    Cornell University, Ithaca, New York, USA
  
  Funding: DOE DE-SC0013571 NSF DGE-1650441
In order to reduce the vertical emittance at the Cornell Electron Storage Ring (CESR), we first measure and correct the vertical orbit, dispersion, and coupling. However, due to the finite resolution of our optics measurements, we still retain a significant residual emittance. In order to correct this further, we made use of the theory of sloppy models, according to which certain high-dimensionality systems can be modeled with significantly fewer "eigenparameters" that still contain most of the effect on the desired objective, in this case, the emittance.* However, we noted that using these knobs for tuning often resulted in increased vertical orbit errors. In an attempt to constrain these, we have applied multi-objective genetic algorithms to this problem. We have found that it can be more efficient to run such algorithms using our eigenparameters as the genes to be varied, as opposed to the raw magnet values. When running with the first 8 such knobs as genes, we can get either orbits or beam sizes as good as we obtain with our regular emittance-tuning algorithm which uses all the corrector magnets.
*K.S. Brown and J.P. Sethna, Phys. Rev. E 68, 021904 (2003). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF041  
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SUSPL065
 Online Optimisation of the MAX IV 3 GeV Ring Dynamic Aperture  
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  • D.K. Olsson
    MAX IV Laboratory, Lund University, Lund, Sweden
  
  In order to improve the resilience of the MAX IV 3 GeV ring's beam to a horizontal dipole kick while at the design tunes (42.20, 16.28) the optimisation algorithm RCDS (Robust Conjugate Direction Search) was deployed. The algorithm was able to increase the horizontal acceptance by finding new settings for the sextupole and octupole magnets, whilst leaving the vertical acceptance virtually unchanged. Additionally, the optimisation increased the momentum acceptance of the lattice, increasing beam lifetime.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL047  
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SUSPL066
 Numerical Studies of Normal Conducting Deflecting Cavity Designs for the ELBE Accelerator  
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  • T.G. Hallilingaiah, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • A. Arnold, U. Lehnert, P. Michel
    HZDR, Dresden, Germany
  
  Currently, in the electron linac ELBE there is a single beam line. Therefore, at any given time only single user can use the beam. Moreover, as different user experiments require distinct beam intensity settings, not all the experiments fully utilize the 13 MHz CW beam capability of the facility. To utilize the full beam capacity, multiple beam lines can be established by using an array of transverse deflecting structures. For that, an RF cavity was the design choice due to its inherent advantages with respect to repeatability of the kick voltage amplitude and phase, and the possibility of CW operation in the MHz range. Potential design candidates are the CEBAF RF separator, the three proposed crab cavities for the HL-LHC upgrade project, and a novel NC deflecting cavity design. In this comparative study, the figures of merit of the cavities are computed from electromagnetic field simulations for a transverse voltage of 300 kV. This comparative study supported our selection of the deflecting cavity design for ELBE.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL074  
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SUSPL067
 Measurement of the Internal Dark Current in a High Gradient Accelerator Structure at 17 GHz  
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  • H. Xu, M.A. Shapiro, R.J. Temkin
    MIT/PSFC, Cambridge, Massachusetts, USA
  
  Funding: Work supported by the U.S. Department of Energy, Office of High Energy Physics, under Grant No. DE-SC0015566
We report a study of internal dark current generation by multipactor inside a 17 GHz single cell standing wave disk-loaded waveguide accelerator structure. The multipactor takes place on the side wall of the central cell, driven by the local rf electric and magnetic fields. Theory indicates that a resonant multipactor mode with two rf cycles can be excited near 45 MV/m gradient and a single rf cycle multipactor mode near 60 MV/m. The accelerator structure had two thin slits opened on the side wall of the central cell to directly extract and measure the internal dark current. The dark current was measured as a function of the gradient up to a gradient of 70 MV/m. The experimental results agreed well with theory, showing the two predicted multipactor modes. To further study the effect of the central cell side wall surface properties on the structure performance, we prepared and tested a second structure with the central cell side wall coated with a layer of diamond-like carbon. The comparison of the results showed that the coating reduced the internal dark current and thus enhanced the structure performance considerably. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL033  
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SUSPL068
 Microphonics Suppression in the CBETA Linac Cryomodules  
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  • N. Banerjee, J. Dobbins, F. Furuta, G.H. Hoffstaetter, R.P.K. Kaplan, M. Liepe, P. Quigley, E.N. Smith, V. Veshcherevich
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: This work was performed through the support of New York State Energy Research and Development Agency. The linac cryomodules were constructed with funding from the National Science Foundation.
The Cornell-BNL ERL Test Accelerator (CBETA) is a new multi-turn energy recovery linac currently under construction at Cornell University. It uses two superconducting linacs, both of which are susceptible to microphonics detuning. The high-current injector accelerates electrons to 6 MeV and the main linac accelerates and decelerates electrons by 36 MeV. In this paper, we discuss various measures taken to reduce vibrations caused by instabilities and flow transients in the cryogenic system of the main linac cryomodule. We further describe the use of a Least Mean Square algorithm in establishing a stable Active Microphonics Compensation system for operation of the main linac cavities. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF038  
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SUSPL069
 Surface Characterization of NbTiN Films for Accelerator Applications  
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  • 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) 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL142  
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SUSPL070
 Longitudinal Effects of Trapped Homs in Shanghai Coherent Light Facility  
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  • J.J. Guo, Q. Gu, H.T. Hou, J.H. Tan, M. Zhang
    SINAP, Shanghai, People's Republic of China
  
  Funding: Shanghai Institute of Applied Physics, Chinese Academy of Sciences
Shanghai Coherent Light Facility (SCLF), a superconducting accelerated structure-baesd FEL device, is now under development at Shanghai Institute of Applied Physics, Chinese Academy of Sciences. We investigate effects of cryogenic losses caused by trapped longitudinal high order modes (HOM). Results of calculations are presented for losses caused by HOMs excitation in the acceleration RF system of the continues-wave (CW) linac of SCLF. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL101  
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SUSPL071
 Development of a Superconducting Double-Spoke Cavity at IMP  
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  • T.C. Jiang, H. Guo, Y. He, C.L. Li, L.B. Liu, T. Tan, P.R. Xiong, Z.M. You, W.M. Yue, S.H. Zhang, S.X. Zhang
    IMP/CAS, Lanzhou, People's Republic of China
  
  Superconducting multi-spoke cavities are well-known optional choice for acceleration of heavy ions in medium velocity regimes. The paper describes the design, fabrication and test results of the superconducting double-spoke cavity developed at IMP. After Buffered Chemical Polishing and High pressure Rinsing, one cavity has undergone high gradient RF testing at 4 K in the Vertical Test Stand. We present measurements of the quality factor as a function of accelerating field and maximum field on the surface. Accelerating gradient of more than 15 MV/m is reached with peak electric field of 61 MV/m, and peak magnetic field of 118 mT.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML078  
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SUSPL072
 Insights into the Role of C, N, and O Introduced by Low Temperature Baking on Niobium Cavity Performance  
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  • P.N. Koufalis, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Previous experiments have shown that introducing nitrogen gas during low temperature bakes (120-160 C) of niobium cavities introduces C, N, and O impurities to the first 10-100 nm of the surface. This new treatment results in higher quality factors and even 'anti-Q-slope' in some cases. However, it is not entirely clear the role that each of these impurities plays in the performance enhancement of the cavities. It has been suggested that interstitial N within the first few nm of the surface is solely responsible for the observed enhancement, but little work has been done on the role of C and O. Because both C and O are abundant in much higher quantities than N near the surface, it is important to understand whether they are beneficial or detrimental to cavity performance. We provide further insight into the effects of C and O on cavity performance by baking in an ambient atmosphere rich in CO2 as opposed to N2.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF041  
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SUSPL073
 Modeling of the Frequency and Field Dependence of the Surface Resistance of Impurity-Doped Niobium  
WEPMF046   use link to access more material from this paper's primary paper code  
 
  • J.T. Maniscalco, P.N. Koufalis, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  The anti-Q-slope, a field-dependent decrease in surface resistance observed in impurity-doped niobium, has been investigated extensively in 1.3 GHz cavities. New early research into this effect has recently been performed at higher and lower frequencies, revealing an additional dependence on frequency: the anti-Q-slope is stronger at higher frequencies and weaker at lower frequencies. Several models have been proposed to explain the anti-Q-slope, with varying success in this new frequency-dependent regime. In this work, we analyze recent experimental data from a low-temperature-doped 1.3 GHz cavity and a high-temperature nitrogen-doped 2.6 GHz cavity and discuss the implications of these results on the proposed models.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF046  
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SUSPL074
 Performance of Samples With Novel SRF Materials and Growth Techniques  
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  • 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.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF047  
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SUSPL075
 Effect of Deposition Temperature and Duration on Nb3Sn Diffusion Coating  
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  • U. Pudasaini, M.J. Kelley
    The College of William and Mary, Williamsburg, Virginia, USA
  • G.V. Eremeev, M.J. Kelley, C.E. Reece
    JLab, Newport News, Virginia, USA
  • M.J. Kelley, J. Tuggle
    Virginia Polytechnic Institute and State University, Blacksburg, USA
  
  Funding: Partially authored by Jefferson Science Associates under contract no. DE¬AC05¬06OR23177. Work at College of William & Mary supported by Office of High Energy Physics under grant SC0014475.
Nb3Sn is a potential candidate to replace Nb in SRF accelerator cavities to reduce cost and advance perfor-mance. Tin vapor diffusion is the preferred technique to realize such cavities by growing a few microns thick Nb3Sn coating on the interior surface of the niobium cavity. The coating process typically uses temperatures of 1100-1200 °C for 3-6 hours. It is important to better understand the coating process, and optimize the coating parameters to overcome the current limitation on the performance of Nb3Sn coated SRF cavities. We investi-gate Nb3Sn coatings prepared in the temperature range of 900-1200 °C and duration of 3 - 12 hours using various material characterization tools. Variation of these pa-rameters appears to have notable effect on microstructure and topography of the obtained surface. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL130  
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SUSPL076
 Magnetron Sputtering of Nb3Sn for SRF Cavities  
THPAL129   use link to access more material from this paper's primary paper code  
 
  • 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.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL129  
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SUSPL077
 Beta-SRF - A New Facility to Characterize SRF Materials near Fundamental Limits  
THPML122   use link to access more material from this paper's primary paper code  
 
  • E. Thoeng
    UBC & TRIUMF, Vancouver, British Columbia, Canada
  • R.A. Baartman, R.E. Laxdal, B. Matheson, G. Morris, N. Muller, S. Saminathan
    TRIUMF, Vancouver, Canada
  • A. Chen
    UBC, Vancouver, Canada
  • T. Junginger
    Lancaster University, Lancaster, United Kingdom
  
  Funding: Natural Sciences and Engineering Research Council of Canada (NSERC) & UBC (NSERC) IsoSiM Program
Demands of CW high-power LINAC require SRF cavities operating at the frontier of high accelerating gradient and low RF power dissipation, i.e. high quality factor (Q0). This requirement poses a challenge for standard surface treatment recipes of SRF cavities. In a recent breakthrough, elliptical SRF cavities doped with Nitrogen have been shown to improve Q0 by a factor of 3, close to the fundamental SRF limit. The fundamental mechanisms at microscopic level and optimum doping recipe, however, have still not fully been understood. Materials other than Nb have also been proposed for SRF cavities to overcome the fundamental limit already reached with Nitrogen doping, e.g. Nb3Sn, MgB2, and Nb-SIS multilayer. At TRIUMF, a unique experimental facility is currently being developed to address these issues. This facility will be able to probe local surface magnetic field in the order of the London Penetration Depth (several tens of nm) via \beta decay detection of a low-energy radioactive ion-beam. This allows depth-resolution and layer-by-layer measurement of magnetic field shielding effectiveness of different SRF materials at high-parallel field (up to 200 mT). Design and current development of this facility will be presented here, as well as commissioning and future measurements strategies for new SRF materials. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML122  
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SUSPL078
 Development of Superconducting RF Double Spoke Cavity at IHEP  
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  • Z.Q. Zhou, H.F.S. Feisi, W.M. Pan
    IHEP, Beijing, People's Republic of China
  
  Funding: State Key Development Program for Basic Research of China (Grant No.2014CB845500)
The China Initiative Accelerator Driven System (CiADS) has been approved to transmute long-lived radi-oisotopes in used nuclear fuel into shorter-lived fission products. IHEP is developing a 325MHz double spoke cavity at β0 of 0.5 for the CiADS linac. The cavity shape was optimized to minimize Ep/Ea while keeping Bp/Ep reasonably low, while the multipacting was analyzed. Meanwhile, mechanical design was applied to check stress, Lorentz force detuning and microphonic effects, and to minimize pressure sensitivity. A new RF coupling scheme was proposed to avoid electrons hitting directly on ceramic window. The detailed design for the cavity is addressed in this paper. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF034  
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SUSPL080
 Field and Cost Optimization of a 5 T/m Normal Conducting Quadrupole for the 10-MeV Beam Line of the eLINAC of the Mexican Particle Accelerator Community  
THPML102   use link to access more material from this paper's primary paper code  
 
  • D. Chavez Valenzuela, G.H.I. Maury Cuna, M. Napsuciale Mendivil
    Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
  • J. C. Basilio Ortiz
    CINVESTAV, Mexico City, Mexico
  • P.M. McIntyre, A. Sattarov
    Texas A&M University, College Station, USA
  • C.A. Valerio
    ECFM-UAS, Culiacan, Sinaloa, Mexico
  • B. Yee-Rendón
    KEK, Ibaraki, Japan
  
  The Mexican Particle Accelerator Community is currently designing the first Mexican RF eLINAC that will have three beamlines at 10, 60 and 100 MeV. In this work, we present an optimized design in terms of field quality and production cost for the 5 T/m normal conducting quadrupoles of the 10-MeV beamline. Several candidate materials for the yoke were studied based on their availability and machinability, with the aim to optimize in-house production cost (Mexico) while restricting a low multipole content.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML102  
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SUSPL081
 Sector DC Dipoles Design for the Beam Test Facility Upgrade  
THPAL010   use link to access more material from this paper's primary paper code  
 
  • A. Vannozzi, S. Lauciani, L. Pellegrino, L. Sabbatini, C. Sanelli, G. Sensolini
    INFN/LNF, Frascati (Roma), Italy
  • P. Valente
    INFN-Roma, Roma, Italy
  
  The Beam Test Facility is part of the DAΦNE accelerators system of INFN Frascati National Laboratory. It is a transfer-line optimized for electrons and positrons extracted from the DAΦNE LINAC. An upgrade of the line is scheduled for two purposes: reach a beam energy of 920 MeV (with respect to the actual 750 MeV) and add a new branch to the present transfer line. This new layout foresees six new quadrupoles one fast ramped dipole, two H-shape and one C-shape sector dipoles. The design of the magnets has been completely performed at INFN involving Electromechanical Enterprise partner in the design phase in order to optimise the manufacturing process. This effort lead to a complete set of detailed CAD drawings that can be directly used by manufacturer to build the magnets. The goal is to boost the manufacturing of prototypes and small series from Small and Medium Enterprises. Magnetic measurements will be performed at INFN. This poster is focused on the realization of the two full iron yoke H-shape and C-shape dipoles, respectively with 45 and 15 bending angle. They are characterized by a high flux density of 1.7 T in a gap of 35 mm. They have a bending radius of 1.8 m  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL010  
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SUSPL082
 Design of Beam Position Fast-Correction Magnet Power Supply for HALS  
THPML124   use link to access more material from this paper's primary paper code  
 
  • Z.X. Shao, H. Gao, L. Wang, H.Y. Zhang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  Funding: Supported by 'Hefei Advanced Light Source Pre-research Project'
Hefei Advanced Light Source (HALS) is the fourth-generation radiation light source that is being pre-researched in China. Ultra-low emittance of the beam requires higher performance of power supply system. We designed a fast correcting power supply for the beam measurement needs. We adopted the all-digital method, the current closed-loop feedback used the AD7766 with 24-bit resolution as its A/D converter. And we added the corresponding constant temperature control, chain protection, etc. The small-signal frequency response of this system can reach more than 5kHz. The detail design scheme is described in this paper. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML124  
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SUSPL084
 LASE Surfaces for Mitigation of Electron Cloud in Accelerators  
THPAL133   use link to access more material from this paper's primary paper code  
 
  • B.S. Sian
    UMAN, Manchester, United Kingdom
  • O.B. Malyshev, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  Vacuum chamber surface characteristics such as the photon and secondary electron yields (PEY and SEY) are critical parameters in the formation of an electron cloud, a serious problem that limits the performance of proton and positron accelerators. A few years ago it was discovered by the Vacuum Solutions Group at Daresbury laboratory that Laser Ablation Surface Engineering (LASE) could provide surfaces with SEY<1 [1,2]. The LASE surfaces are considered as a baseline solution for electron cloud miti-gation in the Future Circular Collider (FCC). However, these surfaces are undergoing further optimisation for the FCC application. While keeping SEY<1 the surfaces should meet the following criteria: Low outgassing, Low particulate generation and low surface resistance. In this paper we will report a number of new surfaces created using the LASE technique with different laser parameters (wavelength, scan speed, pitch, repetition rate, power, and pulse length) and their effect on the SEY, surface re-sistance and vacuum properties, etc  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL133  
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SUSPL086
 Preliminary Design of a Cooling System for the LHC Injection Kicker Magnets  
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  • L. Vega Cid, M.J. Barnes, L. Ducimetière, M.T. Moester, V. Vlachodimitropoulos, W.J.M. Weterings
    CERN, Geneva, Switzerland
  • A. Abánades
    ETSII UPM, Madrid, Spain
  
  The CERN Large Hadron Collider (LHC) is equipped with two fast pulsed magnet systems (MKIs) that inject particle beams from the injector chain. Future operation for High Luminosity LHC (HL-LHC) with high intensity beams will cause heating of the ferrite yokes of the MKIs beyond their Curie temperature, preventing injection until the yokes cool down. Beam coupling impedance studies show that it is possible to move a substantial portion of the beam induced power deposition from the upstream ferrite yokes, which are the yokes with the highest power deposition, to ferrite rings located at the upstream end of the magnet. Thermal predictions show that this power redistribution, combined with the installation of a cooling system around the rings, will maintain the temperatures of all the yokes and ferrite rings below their Curie point. Since the rings are not pulsed to high voltage, whereas the ferrite yokes are, the installation of a cooling system is feasible around the rings. The proposed design of the cooling system will be tested to ensure good performance before its installation on the MKIs. The details of the simulations and the design process are reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK001  
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SUSPL087
 A NEW PRODUCTION PROCESS FOR UCx TARGETS FOR RADIOACTIVE ISOTOPE BEAMS AT TRIUMF  
THPML131   use link to access more material from this paper's primary paper code  
 
  • M. S. Cervantes, P. Fouquet-Métivier, A. Gottberg, P. Kunz, L. Lambert, A. Mjøs, J. Wong
    TRIUMF, Vancouver, Canada
  • M. S. Cervantes
    UVIC, Victoria, Canada
  • P. Fouquet-Métivier
    ENSCM, Montpellier, France
  • A. Gottberg
    Victoria University, Victoria, B.C., Canada
  
  TRIUMF has the objective of producing radioactive isotope beams (RIB) using the ISOL method. Radioactive isotopes are used in experiments in different areas of science. At the TRIUMF-ISAC facility, a 500 MeV proton driver beam impinges onto different targets and induces nuclear reactions in them. The isotopes obtained in this way then diffuse out of the target material before they are ionized and extracted to form an isotope beam. Targets of uranium carbide with excess of graphite (UCx) are the most requested targets at TRIUMF. ARIEL, TRIUMF's flagship project, aims at increasing the radioactive isotope production capabilities to satisfy the growing demand of radioactive isotopes. The current production method of UCx targest does not have the means to supply enough UCx targets to satisfy ARIEL's demand, therefore, a new method for efficient UCx target material synthesis is being developed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML131  
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SUSPL088
 Development of a Proton-to-Neutron Converter for Radioisotope Production at ISAC-TRIUMF  
THPAL117   use link to access more material from this paper's primary paper code  
 
  • L. Egoriti, P.G. Bricault, T. Day Goodacre, A. Gottberg
    TRIUMF, Vancouver, Canada
  • M. Delonca, R.M. Dos Santos Augusto, J.P. Ramos, S. Rothe, T. Stora
    CERN, Geneva, Switzerland
  • M. Dierckx, D. Houngbo, L. Popescu
    SCK•CEN, Mol, Belgium
  • R.M. Dos Santos Augusto
    LMU, München, Germany
  
  At ISAC-TRIUMF, a 500 MeV proton beam is impinged upon thick targets to induce nuclear reactions to pro-duce reaction products that are delivered as a Radioactive Ion Beam (RIB) to experiments. Uranium carbide is among the most commonly used target materials which produces a vast radionuclide inventory coming from both spallation and fission- events. This can also represent a major limitation for the successful delivery of certain RIBs to experiments since, for a given mass, many isobar-ic isotopes are to be filtered by the dipole mass separator. These contaminants can exceed the yield of the isotope of interest by orders of magnitude, often causing a significant reduction in the sensitivity of experiments or even making them impossible. The design of a 50 kW proton-to-neutron (p2n) converter-target is ongoing to enhance the production of neutron-rich nuclei while significantly reducing the rate of neutron-deficient contaminants. The converter is made out of a bulk tungsten block which converts proton beams into neutrons through spallation. The neutrons, in turn, induce pure fission in an upstream UCx target. The present target design and the service infrastructure needed for its operation will be discussed in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL117  
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SUSPL089
 Preliminary Emittance Measurement of Laser Driven Proton Beam Employing a Quadruple Triplet Magnet  
THPAL071   use link to access more material from this paper's primary paper code  
 
  • Wu,M.J. Wu, Y.X. Geng, Q. Liao, C. Lin, H.Y. Lu, Y.R. Lu, W.J. Ma, Y.R. Shou, X. Xu, X.Q. Yan, Y.Y. Zhao, J.G. Zhu, K. Zhu
    PKU, Beijing, People's Republic of China
  
  The Compact Laser Plasma Accelerator (CLAPA) has been built recently at Peking University, which composed of a 200TW laser acceleration platform and a beam line system. Proton with energy spread of <1%, up to 10 pC charge and different energies below 10 MeV have been produced and transported to the irradiation platform. Emittance is a critical parameter for beam transportation. The preliminary emittance measurement has been per-formed for CLAPA's proton beams using the quadrupole scan technique (QST). In the experiment, the focal spot size of the proton beam was changed by scanning the current of a quadrupole triplet magnet. The result shows that the normalized emittance is smaller than 0.01 mm·mrad for 5 MeV laser driven protons, which is on the same level of the previously reported work.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL071  
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SUSPL090
 Dynamic Tuner Development for Medium β Superconducting Elliptical Cavities  
THPAL034   use link to access more material from this paper's primary paper code  
 
  • C. Contreras-Martinez, P.N. Ostroumov
    FRIB, East Lansing, USA
  • E. Borissov, S. Cheban, Y.M. Pischalnikov, V.P. Yakovlev, J.C. Yun
    Fermilab, Batavia, Illinois, USA
  
  Funding: Work supported by U.S. DOE SCGSR program under contract number DE-SC0014664, Michigan State University, and Fermi Research Alliance under contract N. DEAC02-07CH11959 with the U.S. DOE
The Facility for Rare Isotope Beams (FRIB) is developing a 5-cell 644 MHz βopt=0.65 elliptical cavity for a future linac energy upgrade to 400 MeV/u for the heaviest uranium ions. Superconducting elliptical cavities operated in continuous wave, such as the ones for FRIB, are prone to microphonics which can excite mechanical modes of the cavities. It has been shown that the detuning due to microphonics can be mitigated with the use of piezo actuators (fast tuner) as opposed to the costly option of increasing the input RF power. The FRIB slow/fast dynamic tuner will be based on the Fermilab experience with similar tuners like those developed for the linac coherent light source (LCLS) II and proton improvement plan (PIP) II. This paper will present the results of tuner properties on the bench. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL034  
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SUSPL093
 Very-High Energy Electron (VHEE) Studies at CERN's CLEAR User Facility  
MOPML023   use link to access more material from this paper's primary paper code  
 
  • A. Lagzda, R.M. Jones
    UMAN, Manchester, United Kingdom
  • A. Aitkenhead, K. Kirkby, R. MacKay, M. Van Herk
    The Christie NHS Foundation Trust, Manchester, United Kingdom
  • R. Corsini, W. Farabolini
    CERN, Geneva, Switzerland
  
  Funding: Science and Technology Facilities Council (STFC) - United Kingdom
Here we investigate how inserts of various densities (0.001-2.2 g/cm3) affect the dose distribution properties of VHEE beams at ~150 MeV. A range variation comparison was also made with clinical proton beams using TOPAS/GEANT4 Monte Carlo simulations. In addition, we assess the viability of scattering foils for optimizing the size of VHEE beams for radiotherapy purposes. The experiments were conducted at CERN's CLEAR user facility. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML023  
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SUSPL094
 Timing Resolution for an Optical Fibre-Based Detector in a 74 MeV Proton Therapy Beam  
MOPML072   use link to access more material from this paper's primary paper code  
 
  • C.A. Penner
    UBC & TRIUMF, Vancouver, British Columbia, Canada
  • C. Duzenli
    UBC, Vancouver, B.C., Canada
  • C.M. Hoehr, C. Lindsay
    TRIUMF, Vancouver, Canada
  • S. O'Keeffe
    University of Limerick, Limerick, Ireland
  
  A Terbium activated Gadolinium Oxysulfide (Gd2O2S:Tb)-filled optical fibre sensor was developed and tested as a proton therapy beam dosimeter on a 74 MeV proton beam. Tests were carried out at the TRIUMF proton therapy centre, where a passively scattered beam is used for treatment. To create a clinically relevant spread-out Bragg peak, a modulator wheel with steps of varying thickness is employed. To determine the sensor's response in a 23 mm spread out Bragg peak, the sensor signal was sampled at depth intervals of 0.79 mm along the beam axis in a water phantom. The resulting data showed a periodic variation in the signal corresponding to the rotation of the modulator wheel and related to the depth in water of the detector. This timing resolution in the sensor response could find application in quality assurance for modulated proton beams.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML072  
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SUSPL095
 Implementation of a Non-Invasive Online Beam Monitor at a 60 MeV Proton Therapy Beamline  
MOPML024   use link to access more material from this paper's primary paper code  
 
  • R. Schnuerer, C.P. Welsch, S.L. Yap, H.D. Zhang
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • O. Girard, G.J. Haefeli
    EPFL, Lausanne, Switzerland
  • C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  
  To fully exploit the advantageous dose distribution profiles of ion radiotherapy, an exact knowledge of the beam properties through online beam monitoring is essential, ensuring thus an effective dose delivery to the patient. One potential candidate for an online beam monitor is the LHCb Vertex Locator (VELO). This detector, originally developed for the LHCb experiment, has been adapted to the specific conditions of the clinical environment in a proton therapy centre. The semicircular design and position of its sensitive silicon detector offers a non-invasive way to measure the beam intensity without interfering with the beam core. In this contribution, modifications for VELO are described. The detector is synchronized with the readout of a locally-constructed Faraday Cup and the 25.7 MHz RF frequency of the cyclotron at the Clatterbridge Cancer Centre (CCC). Geant4 Monte Carlo simulations investigate the integration of the detector in the treatment line and behaviour of the beam during delivery. The capability of VELO as a beam monitor will be assessed by measuring the beam current and by monitoring the beam profile along the beamline this summer.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML024  
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SUSPL096
 Numerical Simulations to Evaluate and Compare the Performances of Existing and Novel Degrader Materials for Proton Therapy  
MOPML020   use link to access more material from this paper's primary paper code  
 
  • R. Tesse, A. Dubus, N. Pauly
    ULB - FSA - SMN, Bruxelles, Belgium
  • C. Hernalsteens, W.J.G.M. Kleeven, F. Stichelbaut
    IBA, Louvain-la-Neuve, Belgium
  
  The performance of the energy degrader in terms of beam properties directly impacts the design and cost of cyclotron-based proton therapy centers. The aim of this study is to evaluate the performances of different existing and novel degrader materials. The quantitative estimate is based on detailed Geant4 simulations that analyze the beam-matter interaction and provide a determination of the beam emittance increase and transmission. Comparisons between existing (aluminium, graphite, beryllium) and novel (boron carbide and diamond) degrader materials are provided and evaluated against semi-analytical models of multiple Coulomb scattering. The results showing a potential in emittance reduction for novel materials are presented and discussed in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML020  
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SUSPL097
 High Gradient Performance of an S-Band Backward Traveling Wave Accelerating Structure for Medical Hadron Therapy Accelerators  
MOPML043   use link to access more material from this paper's primary paper code  
 
  • A. Vnuchenko, C. Blanch Gutiérrez, D. Esperante Pereira
    IFIC, Valencia, Spain
  • S. Benedetti, N. Catalán Lasheras, A. Grudiev, B. Koubek, G. McMonagle, I. Syratchev, B.J. Woolley, W. Wuensch
    CERN, Geneva, Switzerland
  • A. Faus-Golfe
    LAL, Orsay, France
  • T.G. Lucas, M. Volpi
    The University of Melbourne, Melbourne, Victoria, Australia
  • S. Pitman
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  
  The high-gradient performance of an accelerating structure prototype for a medical proton linac is presented. The structure was designed and built using technology developed by the CLIC collaboration and the target application is the TULIP (Turning Linac for Proton therapy) proposal developed by the TERA foundation. The special feature of this design is to produce gradient of more than 50 MV /m in low-β accelerating structures (v/c=0.38). The structure was tested in an S-band test stand at CERN. During the tests, the structure reached over above 60 MV/m at 1.2 μs pulse length and breakdown rate of about 5x10-6 bpp. The results presented include ultimate performance, long term behaviour and measurements that can guide future optimization.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML043  
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