HB2016 - Table of Session: MOPR (Posters Right of Main Hall)

Paper	Title	Page
MOPR001	Figure-8 Storage Ring – Investigation of the Scaled Down Injection System	41
	H. Niebuhr, A. Ates, M. Droba, O. Meusel, D. Noll, U. Ratzinger, J.F. Wagner IAP, Frankfurt am Main, Germany
	To store high current ion beams up to 10 A, a superconducting storage ring (F8SR) is planned at Frankfurt university. For the realisation, a scaled down experimental setup with normalconducting magnets is being build. Investigations of beam transport in solenoidal and toroidal guiding fields are in progress. At the moment, a new kind of injection system consisting of a solenoidal injection coil and a special vacuum vessel is under development. It is used to inject a hydrogen beam sideways between two toroidal magnets. In parallel operation, a second hydrogen beam is transported through both magnets to represent the circulating beam. In a second stage, an ExB-Kicker will be used as a septum to combine both beams into one. The current status of the experimental setup will be shown. For the design of the experiments, computer simulations using the 3D simulation code bender were performed. Different input parameters were checked to find the optimal injection and transport channel for the experiment. The results will be presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR001
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MOPR002	Study on the Magnetic Measurement Results of the Injection System for CSNS/RCS	46
	M.Y. Huang, S. Fu, N. Huang, L. Huo, H.F. Jipresenter, W. Kang, Y.Q. Liu, J. Peng, J. Qiu, L. Shen, S. Wang, X. Wu, S.Y. Xu, J. Zhang, G.Z. Zhou IHEP, Beijing, People's Republic of China
	Funding: Work supported by National Natural Science Foundation of China (11205185) A combination of the H⁻ stripping and phase space painting method is used to accumulate a high intensity beam in the Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS). The injection system for CSNS/RCS consists of three kinds of magnets: four direct current magnets (BC1-BC4), eight alternating current magnets (BH1-BH4 and BV1-BV4), two septum magnets (ISEP1 and ISEP2). In this paper, the magnetic measurements of the injection system were introduced and the data analysis was processed. The field uniformity and magnetizing curves of these magnets were given, and then the magnetizing fitting equations were obtained.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR002
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MOPR004	H⁻ Charge Exchange Injection for XiPAF Synchrotron	49
	H.J. Yao, X. Guan, G.R. Li, X.W. Wang, Q.Z. Xing, S.X. Zheng TUB, Beijing, People's Republic of China
	The physics design of the H⁻ charge exchange injection system for Xi’an Proton Application Facility (XiPAF) synchrotron with the missing dipole lattice is discussed. The injection scheme is composed of one septum magnet, three chicane dipoles, two bump magnets and one carbon stripping foil. A 7 μg/cm² carbon foil is chosen for 7 MeV H⁻ beam for high stripping efficiency and low coulomb scattering effect. The simulation results of the horizontal and vertical phase space painting finished by two bumper magnets and mismatching respectively are presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR004
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MOPR005	RF-Knockout Slow Extraction Design for XiPAF Synchrotron	52
	H.J. Yao, X. Guan, G.R. Li, X.W. Wang, Q. Zhang, S.X. Zheng TUB, Beijing, People's Republic of China
	The physics design of slow extraction for Xi’an Proton Application Facility (XiPAF) synchrotron is discussed. The extraction scheme is composed of two resonant sextupoles, one electrostatic septum (ES) and two septum magnets. The phase space diagram under the Hardt condition at the entrance of ES and the last three turn’s trajectory before extraction are presented. A program is written with C++ to simulate slow extraction process by RF-knockout (RF-KO), the calculation results of dual frequency modulation (FM) and amplitude modulation (AM) are given, and the standard deviation of the fluctuation parameter R1 can be limited 0.2 with optimum parameters under a sampling frequency of about 10 kHz.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR005
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MOPR006	Design of the 230MeV Proton Accelerator for Xi'an Proton Application Facility	55
	H.J. Yao, H.B. Chen, C. Cheng, C.T. Du, L. Du, T.B. Du, X. Guan, W.-H. Huang, H. Jiang, G.R. Li, C.-X. Tang, R. Tang, D. Wang, W. Wang, X.W. Wang, L. Wu, Q.Z. Xing, Y. Yang, Z. Yang, H.J. Zeng, H.Y. Zhang, Q. Zhang, Q.Z. Zhang, S.X. Zheng TUB, Beijing, People's Republic of China W. Chen NINT, Xi'an, People's Republic of China W.Q. Guan, Y. He, J. Li NUCTECH, Beijing, People's Republic of China S.-Y. Lee Indiana University, Bloomington, Indiana, USA M.T. Qiu, B.C. Wang, Y.P. Wang, Z.M. Wang, Y.H. Yan, H.Z. Zhang, C. Zhao State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Shannxi, People's Republic of China
	We report a design of the 230 MeV proton accelera-tor, the Xi’an Proton Application Facility (XiPAF), which will be located in Xi’an city, China. The facility will provide proton beam with the maximum energy of 230 MeV for the research of the single event effect. The facility, composed of a 230 MeV synchrotron, a 7 MeV H⁻ linac injector and two experimental stations, will provide a flux of 10⁵~10⁸ p/cm²/s with the uni-formity of better than 90% on the 10 cm×10 cm sample.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR006
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MOPR007	Cold and High Power Test of Large Size Magnetic Alloy Core for XiPAF's Synchrotron	59
	G.R. Li, X. Guan, W.-H. Huang, X.W. Wang, Z. Yang, H.J. Yaopresenter, H.J. Zeng, S.X. Zheng TUB, Beijing, People's Republic of China
	A compact magnetic alloy (MA) loaded cavity is under development for XiPAF's synchrotron. The cavity contains 6 large size MA cores, each is independently coupled with solid state power amplifier. Two types of MA core are proposed for the project. We have developed a single core model cavity to verify the impedance model and to test the properties of MA cores under high power state. The high power test results are presented and discussed.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR007
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MOPR008	Pressure Profiles Calculation for the CSRm and BRing	62
	P. Li, Z. Chai, Z. Dong, X.C. Kang, M. Li, S. Li, W.L. Li, C.L. Luo, R.S. Mao, J. Meng, J.C. Yang, Y.J. Yuan, W.H. Zheng IMP/CAS, Lanzhou, People's Republic of China
	Funding: National Natural Science Foundation of China (Project No. 11305227) A new large scale accelerator facility is being designed by Institute of Modern Physics (IMP) Lanzhou, which is named as the High Intensity heavy-ion Accelerator Facility (HIAF). This project consists of ion sources, Linac accelerator, synchrotrons (BRing) and several experimental terminals. During the operation of Bring, the heavy ion beams will be easily lost at the vacuum chamber along the BRing when it is used to accumulate intermediate charge state particles. The vacuum pressure bump due to the ion-induced desorption in turn leads to an increase in beam loss rate. In order to accumulate the beams to higher intensity to fulfill the requirements of physics experiments and for better understanding of the dynamic vacuum pressure caused by the beam loss, a dynamic vacuum pressure simulation program has been developed. Vacuum pressure profiles are calculated and compared with the measured data based on the current synchrotron (CSRm). Then the static vacuum pressure profiles of the BRing and one type of pump which will be used in the BRing are introduced in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR008
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MOPR009	Transverse Beam Splitting Made Operational: Recent Progress of the Multi-Turn Extraction at the CERN Proton Synchrotron	65
	A. Huschauer, J.C.C.M. Borburgh, S. Damjanovic, S.S. Gilardoni, M. Giovannozzi, M. Hourican, K. Kahle, G. Le Godec, O. Michels, G. Sterbini CERN, Geneva, Switzerland C. Hernalsteens IBA, Louvain-la-Neuve, Belgium
	Following a successful commissioning period, the Multi-Turn Extraction (MTE) at the CERN Proton Synchrotron (PS) has been applied for the fixed-target physics programme at the Super Proton Synchrotron (SPS) since September 2015. This exceptional extraction technique was proposed to replace the long-serving Continuous Transfer (CT) extraction, which has the drawback of inducing high activation in the ring. MTE exploits the principles of non-linear beam dynamics to perform loss-free beam splitting in the horizontal phase space. Over multiple turns, the resulting beamlets are then transferred to the downstream accelerator. The operational deployment of MTE was rendered possible by the full understanding and mitigation of different hardware limitations and by redesigning the extraction trajectories and non-linear optics, which was required due to the installation of a dummy septum to reduce the activation of the magnetic extraction septum. The results of the related experimental and simulation studies, a summary of the 2015 performance analysis, as well as more recent performance improvements are presented in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR009
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MOPR010	Machine Element Contribution to the Longitudinal Impedance Model of the CERN SPS	71
	T. Kaltenbacher, F. Caspers, C. Vollinger CERN, Geneva, Switzerland
	This contribution describes the current longitudinal impedance model of the SPS and studies carried out in order to improve, extend and update it. Specifically, new sources of impedances have been identified, evaluated and included in the model. One finding are low Q and low-frequency (LF; here below 1 GHz) resonances which occur due to enamelled flanges in combination with external cabling e.g. ground loops. These resonances couple to the beam through the gap with enamel coating which creates an open resonator. Since this impedance is important for beam stability in the CERN Proton Synchrotron (PS), RF by-passes were installed on the enamelled flanges, and their significance for the SPS beam is currently under investigation. Simulations, bench and beam measurements were used to deduce model parameters for beam dynamic simulations.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR010
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MOPR011	The SPS 200 MHz TWC Impedance after the LIU Upgrade	76
	T. Roggen, R. Calaga, F. Caspers, T. Kaltenbacher, C. Vollinger CERN, Geneva, Switzerland
	Funding: Fellowship co-funded by the European Union as a Marie Curie action (Grant agreement PCOFUND-GA-2010-267194) within the Seventh Framework Programme for Research and Technological Development. As a part of the LHC Injectors Upgrade project (LIU) the 200 MHz Travelling Wave Cavities (TWC) of the Super Proton Synchrotron (SPS) will be upgraded. The two existing five-section cavities will be rearranged into four three-section cavities (using two existing spare sections), thereby increasing the total voltage from 7 MV (I_RF = 1.5 A) to 10 MV (I_RF = 3.0 A). Projections of the HL-LHC (High Luminosity Large Hadron Collider) era are conceived by the macro-particle simulation code BLonD, that makes use of an impedance model of the SPS, developed from a thorough survey of machine elements. This paper analyses the impedance contribution of the 200 MHz cavities in the two configurations, using electromagnetic simulations. Measurements of the existing cavities in the SPS and a single-section prototype are also presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR011
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MOPR012	The New HL-LHC Injection and Transport Protection System	81
	F.M. Velotti, W. Bartmann, C. Bracco, M.A. Fraser, B. Goddard, V. Kain, A. Lechner, M. Meddahi CERN, Geneva, Switzerland
	The High-Luminosity LHC (HL-LHC) upgrade represents a challenge for the full chain of its injectors. The aim is to provide beams with a brightness a factor of two higher than the present maximum achieved. The 450 GeV beams injected into the LHC are directly provided by the Super Proton Synchrotron (SPS) via two transfer lines (TL), TI2 and TI8. Such transfer lines are both equipped with a passive protection system to protect the LHC aperture against ultra-fast failures of the extraction and transport systems. In the LHC instead, the injection protection system protects the cold apertures against possible failures of the injection kicker, MKI. Due to the increase of the beam brightness, these passive systems need to be upgraded. In this paper, the foreseen and ongoing modifications of the LHC injection protection system and the TL collimators are presented. Simulations of the protection guaranteed by the new systems in case of failures are described, together with benchmark with measurements for the current systems.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR012
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MOPR014	Corrector Magnets for the CBETA and eRHIC Projects and Other Hadron Facilities*	87
	N. Tsoupas, S.J. Brooks, A.K. Jain, F. Méot, V. Ptitsyn, D. Trbojevic BNL, Upton, Long Island, New York, USA
	Funding: Work supported by the U.S. Department of Energy under contract DE- SC0012704. The Cbeta project[1] is a prototype electron accelerator for the proposed eRHIC project[2]. The electron accelerator is based on the Energy Recovery Linac (ERL) and the Fixed Field Alternating Gradient (FFAG) principles. The FFAG arcs of the accelerator are comprised of one focusing and one defocusing quadrupoles which are designed as Halbach-type permanent magnet quadrupoles[3]. We propose window frame electro-magnets surrounding the Halbach magnets to be used as normal and skew dipoles correctors and quadrupole correctors. We will present results from OPERA-3D calculations of the effect of these corrector magnets on the magnetic field of the main quadrupole magnets and the results will be compared with experimental measurements. We will also discuss applications of permanent magnets with such correctors for hadron beam facilities. [1] http://arxiv.org/abs/1504.00588 [2] http://arxiv.org/ftp/arxiv/papers/1409/1409.1633.pdf [3] K. Halbach, NIM 169 (1980) pp. 1-10
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR014
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MOPR016	Mitigation of Numerical Noise for Beam Loss Simulations	90
	F. Kesting IAP, Frankfurt am Main, Germany G. Franchetti GSI, Darmstadt, Germany
	Numerical noise emerges in self-consistent simulations of charged particles, and its mitigation is investigated since the first numerical studies in plasma physics. In accelerator physics, recent studies find an artificial diffusion of the particle beam due to numerical noise in particle-in-cell tracking, which is of particular importance for high intensity machines with a long storage time, as the SIS100 at FAIR or in context of the LIU upgrade at CERN. In beam loss simulations for these projects artificial effects must be distinguished from physical beam loss. Therefore, it is important to relate artificial diffusion to artificial beam loss, and to choose simulation parameters such that physical beam loss is well resolved. As a practical tool, we therefore suggest a scaling law to find optimal simulation parameters for a given maximum percentage of acceptable artificial beam loss.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR016
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MOPR017	Status of the Beam Instrumentation System of CSNS	95
	J.L. Sun, J. Pengpresenter, R.Y. Qiu, T. Yang CSNS, Guangdong Province, People's Republic of China W.L. Huang, F. Li, P. Li, M. Meng, J.M. Tian, T.G. Xu, Zh.H. Xu, L. Zeng IHEP, Beijing, People's Republic of China
	The first section DTL commissioning of China Spallation Neutron Source (CSNS) project has been successful finished in January, 2016. The H⁻ beam can be accelerated to 21.6 MeV at peak current 18 mA, achieved the design point. Different elements of the beam instrumentation system have been tested during the commissioning, including BPM, CT, FCT, WS, EM, BLM, and corresponding electronics and control systems. High accuracy phase measurement (precision @ ±1°) system has been started into operation. Beam loss monitor (BLM) for low energy, 3 MeV to 21.6 MeV, has been tested too, and got very positive results. For the LRBT, RCS and RTBT, different type wire scanner, BPM, WCM, CT were designed. The monitors fit for the high-radiation environments were considered. All the physical design work has been finished, and being manufactured. Lab test will be started in June and the LINAC commissioning (beam energy up to 80 MeV) will be started in August.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR017
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MOPR018	XAL Applications Development for CSNS Transport Lines	98
	Y. Li, Z.P. Li, W.B. Liu IHEP, Beijing, People's Republic of China J. Pengpresenter CSNS, Guangdong Province, People's Republic of China
	XAL is an application programming framework initially developed at the Spallation Neutron Source (SNS). It has been employed as a part of control system via con-nection to EPICS to provide application programs for beam commissioning at the China Spallation Neutron Source (CSNS). Several XAL-based applications have been developed for Beam Transport line at CSNS and successfully applied in the MEBT and DTL-1 beam commissioning. These applications will be discussed in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR018
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MOPR020	Space Charge Effects of High Intensity Beams at BRing	101
	J. Li, J.C. Yang IMP/CAS, Lanzhou, People's Republic of China
	Funding: Work supported by NSFC (Grant No. 11475235) Space charge effects perform one of the main intensity limitations for low energy synchrotron. Large tune spread and crossing resonance stop-bands can hardly be avoided for intensive heavy ion beam at high intensity. Several subjects like Betatron and structure resonance, and tune spread are discussed. Simulations are carried out for 238U³⁴⁺ focusing on emittance and intensity change during RF capture at the injection energy at the booster ring of the High Intensity heavy ion Accelerator Facility (HIAF). lijie@impcas.ac.cn
	Poster MOPR020 [1.157 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR020
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MOPR021	Overview of the ESSnuSB Accumulator Ring	105
	M. Olvegård, T.J.C. Ekelöf Uppsala University, Uppsala, Sweden E. Benedetto, M. Cieslak-Kowalska, M. Martini, H.O. Schönauer, E.H.M. Wildner CERN, Geneva, Switzerland
	The European Spallation Source (ESS) is a research center based on the world’s most powerful proton driver, 2.0 GeV, 5 MW on target, currently under construction in Lund. With an increased pulse frequency, the ESS linac could deliver additional beam pulses to a neutrino target, thus giving an excellent opportunity to produce a high-performance ESS neutrino Super-Beam (ESSnuSB). The focusing system surrounding the neutrino target requires short proton pulses. An accumulator ring and acceleration of an H⁻ beam in the linac for charge-exchange injection into the accumulator could provide such short pulses. In this paper we present an overview of the work with optimizing the accumulator design and the challenges of injecting and storing 1.10¹⁵ protons per pulse from the linac. In particular, particle tracking simulations with space charge will be described.
	Poster MOPR021 [2.731 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR021
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MOPR022	Longitudinal Particle Tracking Code for a High Intensity Proton Synchrotron	110
	M. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	We have been developing a longitudinal particle tracking code to design and investigate the beam behavior of the J-PARC proton synchrotrons. The code calculate the longitudinal particle motion with a wake voltage and a space charge effect. The most different point from the other codes is that a synchronous particle motion is calculated from the bending magnetic field pattern. This means the synchronous particle is independent from an acceleration frequency pattern. This feature is useful to check the adiabaticity of the synchrotron. The code also calculates the longitudinal emittance and the filling factor at an rf bucket under the multi-harmonics. We will describe the feature of the code.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR022
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MOPR023	Interpretation of Wire-Scanner Asymmetric Profiles in a Low-Energy Ring	115
	M. Cieslak-Kowalska, E. Benedettopresenter CERN, Geneva, Switzerland
	In the CERN PS Booster, wire-scanner profile measurements performed at injection energy are affected by a strong asymmetry. The shape was reproduced with the code pyOrbit, assuming that the effect is due to the beam evolution during the scans, under the influence of space-charge forces and Multiple Coulomb Scattering at the wire itself. Reproducing the transverse profiles during beam evolution allows to use them reliably as input for simulation benchmarking.
	Poster MOPR023 [0.482 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR023
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MOPR024	General Formula to Deduce the Space Charge Tune Spread From a Quadrupolar Pick-Up Measurement	120
	E. Métral CERN, Geneva, Switzerland
	In 1966, W. Hardt derived the oscillation frequencies obtained in the presence of space charge forces and gradients errors for elliptical beams. Since then, a simple formula is usually used to relate the shift of the quadrupolar mode (obtained from the quadrupolar pick-up) and the space charge tune spread, depending only on the ratio between the two transverse equilibrium beam sizes. However, this formula is not always valid, in particular for machines running close to the coupling resonance Qx = Qy with almost round beams. A new general formula is presented, giving the space charge tune spread as a function of i) the measured shift of the quadrupolar mode, ii) the ratio between the two transverse equilibrium beam sizes and iii) the distance between the two transverse tunes.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR024
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MOPR025	Space Charge Modules for PyHEADTAIL	124
	A. Oeftiger CERN, Geneva, Switzerland S. Hegglin ETH, Zurich, Switzerland
	Funding: CERN, Doctoral Studentship and EPFL, Doctorate PyHEADTAIL is a 6D tracking tool developed at CERN to simulate collective effects. We present recent developments of the direct space charge suite, which is available for both the CPU and GPU. A new 3D particle-in-cell solver with open boundary conditions has been implemented. For the transverse plane, there is a semi-analytical Bassetti-Erskine model as well as 2D self-consistent particle-in-cell solvers with both open and closed boundary conditions. For the longitudinal plane, PyHEADTAIL offers line density derivative models. Simulations with these models are benchmarked with experiments at the injection plateau of CERN's Super Proton Synchrotron.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR025
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MOPR026	Space Charge Mitigation With Longitudinally Hollow Bunches	130
	A. Oeftiger, S. Hancock, G. Rumolo CERN, Geneva, Switzerland
	Funding: CERN, Doctoral Studentship and EPFL, Doctorate Hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN's PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR026
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MOPR027	Dynamic Beta and Beta-Beating Effects in the Presence of the Beam-Beam Interactions	136
	T. Pieloni, X. Buffat, L.E. Medina Medrano, C. Tambasco, R. Tomás CERN, Geneva, Switzerland J. Barranco, P. Concalves Jorge, C. Tambasco EPFL, Lausanne, Switzerland
	The Large Hadron Collider (LHC) has achieved correction of beta beat down to better than 5%. The beam-beam interactions at the four experiments result as extra quadrupole error in the lattice. This will produce a change of the β^* at the experiments and a beating along the arcs which for the High Luminosity LHC (HL-LHC) will be very large. Estimations of these effects will be given with the characterisation of the amplitude dependency. A first attempt to correct his beating is also discussed.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR027
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MOPR028	CERN PS Booster Longitudinal Dynamics Simulations for the Post-LS2 Scenario	140
	D. Quartullo, S.C.P. Albright, E.N. Shaposhnikova, H. Timko CERN, Geneva, Switzerland
	The CERN PS Booster is the first synchrotron in the LHC proton injection chain, it currently accelerates particles from 50 MeV to 1.4 GeV kinetic energy. Several upgrades foreseen by the LHC Injectors Upgrade Program will allow the beam to be accelerated from 160 MeV to 2 GeV after Long Shutdown 2 in 2021. The present RF systems will be replaced by a new one, based on Finemet technology. These and other improvements will help to increase the LHC luminosity by a factor of ten. In order to study beam stability in the longitudinal plane simulations have been performed with the CERN BLonD code, using an accurate longitudinal impedance model and a reliable estimation of the longitudinal space charge. Particular attention has been dedicated to the three main features that currently let the beam go stably through the ramp: Double RF operation in bunch-lengthening mode to reduce the transverse space charge tune spread, exploitation of feedback loops to damp dipole oscillations, and controlled longitudinal emittance blow-up. RF phase noise injection has been considered to study if it could complement or substitute the currently used method based on sinusoidal phase modulation.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR028
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MOPR029	On the Impact of Non-Symplecticity of Space Charge Solvers	146
	M. Titze CERN, Geneva, Switzerland
	Funding: German Federal Ministry of Education and Research (BMBF) To guarantee long-term reliability in the predictions of a numerical integrator, it is a well-known requirement that the underlying map has to be symplectic. It is therefore important to examine in detail the impact on emittance growth and noise generation in case this condition is violated. We present a strategy of how to tackle this question and some results obtained for particular PIC and frozen space charge models.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR029
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MOPR030	Simple Models for Beam Loss Near the Half Integer Resonance with Space Charge	150
	C.M. Warsop, D.J. Adams, B. Jones, B.G. Pine STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	The half integer resonance is often used to define the high intensity limit of medium or low energy hadron rings where transverse space charge is significant. However, the mechanism leading to particle loss as beam approaches this resonance, which thus defines the limit, is not clearly understood. In this paper we explore simple models, based on single particle resonance ideas, to see if they describe useful aspects of motion as observed in simulations and experiments of 2D coasting beams on the ISIS synchrotron. Single particle behaviour is compared to 2D self-consistent models to assess when coherent motion begins to affect the single particle motion, and understand the relevance of coherent and incoherent resonance. Whilst the general problem of 2D resonant loss, with non-stationary distributions and non-linear fields is potentially extremely complicated, here we suggest that for a well-designed machine, where higher order pathological loss effects are avoided, a relatively simple model may give valuable insights into beam behaviour and control.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR030
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MOPR031	Development of Physics Models of the ISIS Head-Tail Instability	155
	R.E. Williamson, B. Jones, C.M. Warsop STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	ISIS is the pulsed spallation neutron and muon source at the Rutherford Appleton Laboratory in the UK. Operation centres on a rapid cycling proton synchrotron which accelerates 3·10¹³ protons per pulse (ppp) from 70 MeV to 800 MeV at 50 Hz, delivering a mean beam power of 0.2 MW. As a high intensity, loss-limited machine, research and development at ISIS is focused on understanding loss mechanisms with a view to improving operational performance and guiding possible upgrade routes. The head-tail instability observed on ISIS is of particular interest as it is currently a main limitation on beam intensity. Good models of impedance are essential for understanding instabilities and to this end, recent beam-based measurements of the effective transverse impedance of the ISIS synchrotron are presented. This paper also presents developments of a new, in-house code to simulate the head-tail instability observed and includes benchmarks against theory and comparisons with experimental results.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR031
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MOPR033	Beam Acceleration and Transition Crossing in the Fermilab Booster	160
	V.A. Lebedev, C.M. Bhat, J.-F. Ostiguy Fermilab, Batavia, Illinois, USA
	To suppress eddy currents, the Fermilab rapid cycling Booster synchrotron has no beam pipe; rather, its combined function dipoles are evacuated, exposing the beam directly to the magnet laminations. This arrangement significantly increases the resistive wall impedance of the dipoles and, in combination with the space charge impedance, substantially complicates longitudinal dynamics at transition. Voltage and accelerating phase profiles in the vicinity of transition are typically empirically optimized to minimize beam loss and emittance growth. In this contribution, we present results of experimental studies of beam acceleration near transition. Using comparisons between observed beam parameters and simulations, we obtain accurate calibrations for the RF program and extract quantitative information about parameters of relevance to the Booster laminated magnets longitudinal impedance model. The results are used to analyze transition crossing in the context of a future 50% increase in beam intensity planned for PIP-II, an upgrade of the Fermilab accelerating complex.
	Poster MOPR033 [0.231 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR033
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MOPR034	Suppression of Half-Integer Resonance in Fermilab Booster	164
	V.A. Lebedev, A. Valishev Fermilab, Batavia, Illinois, USA
	The particle losses at injection in the FNAL Booster are one of the major factors limiting the machine performance. The losses are caused by motion non-linearity due to direct space charge and due to non-linearity introduced by large values of chromaticity sextupoles required to suppress transverse instabilities. The report aims to address the former - the suppression of incoherent space charge effects by reducing deviations from the perfect periodicity of linear optics functions. It should be achieved by high accuracy optics measurements with subsequent optics correction and by removing known sources of optics perturbations. The study shows significant impact of optics correction on the half-integer stop band with subsequent reduction of particle loss. We use realistic Booster lattice model to understand the present limitations, and investigate the possible improvements which would allow high intensity operation with PIP-II parameters.
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MOPR035	Electron Lens for the Fermilab Integrable Optics Test Accelerator	170
	G. Stancari, A.V. Burov, K. Carlson, D.J. Crawford, V.A. Lebedev, J.R. Leibfritz, M.W. McGee, S. Nagaitsev, L.E. Nobrega, C.S. Park, E. Prebys, A.L. Romanov, J. Ruan, V.D. Shiltsev, Y.-M. Shin, J.C.T. Thangaraj, A. Valishev Fermilab, Batavia, Illinois, USA D. Noll IAP, Frankfurt am Main, Germany Y.-M. Shin Northern Illinois University, DeKalb, Illinois, USA
	Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the US Department of Energy. The Integrable Optics Test Accelerator (IOTA) is a research machine currently being designed and built at Fermilab. The research program includes the study of nonlinear integrable lattices, beam dynamics with self fields, and optical stochastic cooling. One section of the ring will contain an electron lens, a low-energy magnetized electron beam overlapping with the circulating beam. The electron lens can work as a nonlinear element, as an electron cooler, or as a space-charge compensator. We describe the physical principles, experiment design, and hardware implementation plans for the IOTA electron lens.
	Poster MOPR035 [5.399 MB]
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MOPR036	Spin Tracking of Polarized Protons in the Main Injector at Fermilab	173
	M. Xiao Fermilab, Batavia, Illinois, USA C. Aldred, W. Lorenzon Michigan University, Ann Arbor, Michigan, USA
	The Main Injector (MI) at Fermilab currently produces high-intensity beams of protons at energies of 120 GeV for a variety of physics experiments. Acceleration of polarized protons in the MI would provide opportunities for a rich spin physics program at Fermilab. To achieve polarized proton beams in the Fermilab accelerator com-plex, shown in Fig.1.1, detailed spin tracking simulations with realistic parameters based on the existing facility are required. This report presents studies at the MI using a single 4-twist Siberian snake to determine the depolariz-ing spin resonances for the relevant synchrotrons. Results will be presented first for a perfect MI lattice, followed by a lattice that includes the real MI imperfections, such as the measured magnet field errors and quadrupole misa-lignments. The tolerances of each of these factors in maintaining polarization in the Main Injector will be discussed.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR036
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Paper

Title

Page

Figure-8 Storage Ring – Investigation of the Scaled Down Injection System

41

H. Niebuhr, A. Ates, M. Droba, O. Meusel, D. Noll, U. Ratzinger, J.F. Wagner
IAP, Frankfurt am Main, Germany

To store high current ion beams up to 10 A, a superconducting storage ring (F8SR) is planned at Frankfurt university. For the realisation, a scaled down experimental setup with normalconducting magnets is being build. Investigations of beam transport in solenoidal and toroidal guiding fields are in progress. At the moment, a new kind of injection system consisting of a solenoidal injection coil and a special vacuum vessel is under development. It is used to inject a hydrogen beam sideways between two toroidal magnets. In parallel operation, a second hydrogen beam is transported through both magnets to represent the circulating beam. In a second stage, an ExB-Kicker will be used as a septum to combine both beams into one. The current status of the experimental setup will be shown. For the design of the experiments, computer simulations using the 3D simulation code bender were performed. Different input parameters were checked to find the optimal injection and transport channel for the experiment. The results will be presented.

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MOPR002

Study on the Magnetic Measurement Results of the Injection System for CSNS/RCS

46

M.Y. Huang, S. Fu, N. Huang, L. Huo, H.F. Jipresenter, W. Kang, Y.Q. Liu, J. Peng, J. Qiu, L. Shen, S. Wang, X. Wu, S.Y. Xu, J. Zhang, G.Z. Zhou
IHEP, Beijing, People's Republic of China

Funding: Work supported by National Natural Science Foundation of China (11205185)
A combination of the H⁻ stripping and phase space painting method is used to accumulate a high intensity beam in the Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS). The injection system for CSNS/RCS consists of three kinds of magnets: four direct current magnets (BC1-BC4), eight alternating current magnets (BH1-BH4 and BV1-BV4), two septum magnets (ISEP1 and ISEP2). In this paper, the magnetic measurements of the injection system were introduced and the data analysis was processed. The field uniformity and magnetizing curves of these magnets were given, and then the magnetizing fitting equations were obtained.

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MOPR004

H⁻ Charge Exchange Injection for XiPAF Synchrotron

49

H.J. Yao, X. Guan, G.R. Li, X.W. Wang, Q.Z. Xing, S.X. Zheng
TUB, Beijing, People's Republic of China

The physics design of the H⁻ charge exchange injection system for Xi’an Proton Application Facility (XiPAF) synchrotron with the missing dipole lattice is discussed. The injection scheme is composed of one septum magnet, three chicane dipoles, two bump magnets and one carbon stripping foil. A 7 μg/cm² carbon foil is chosen for 7 MeV H⁻ beam for high stripping efficiency and low coulomb scattering effect. The simulation results of the horizontal and vertical phase space painting finished by two bumper magnets and mismatching respectively are presented.

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MOPR005

RF-Knockout Slow Extraction Design for XiPAF Synchrotron

52

H.J. Yao, X. Guan, G.R. Li, X.W. Wang, Q. Zhang, S.X. Zheng
TUB, Beijing, People's Republic of China

The physics design of slow extraction for Xi’an Proton Application Facility (XiPAF) synchrotron is discussed. The extraction scheme is composed of two resonant sextupoles, one electrostatic septum (ES) and two septum magnets. The phase space diagram under the Hardt condition at the entrance of ES and the last three turn’s trajectory before extraction are presented. A program is written with C++ to simulate slow extraction process by RF-knockout (RF-KO), the calculation results of dual frequency modulation (FM) and amplitude modulation (AM) are given, and the standard deviation of the fluctuation parameter R1 can be limited 0.2 with optimum parameters under a sampling frequency of about 10 kHz.

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MOPR006

Design of the 230MeV Proton Accelerator for Xi'an Proton Application Facility

55

H.J. Yao, H.B. Chen, C. Cheng, C.T. Du, L. Du, T.B. Du, X. Guan, W.-H. Huang, H. Jiang, G.R. Li, C.-X. Tang, R. Tang, D. Wang, W. Wang, X.W. Wang, L. Wu, Q.Z. Xing, Y. Yang, Z. Yang, H.J. Zeng, H.Y. Zhang, Q. Zhang, Q.Z. Zhang, S.X. Zheng
TUB, Beijing, People's Republic of China
W. Chen
NINT, Xi'an, People's Republic of China
W.Q. Guan, Y. He, J. Li
NUCTECH, Beijing, People's Republic of China
S.-Y. Lee
Indiana University, Bloomington, Indiana, USA
M.T. Qiu, B.C. Wang, Y.P. Wang, Z.M. Wang, Y.H. Yan, H.Z. Zhang, C. Zhao
State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Shannxi, People's Republic of China

We report a design of the 230 MeV proton accelera-tor, the Xi’an Proton Application Facility (XiPAF), which will be located in Xi’an city, China. The facility will provide proton beam with the maximum energy of 230 MeV for the research of the single event effect. The facility, composed of a 230 MeV synchrotron, a 7 MeV H⁻ linac injector and two experimental stations, will provide a flux of 10⁵~10⁸ p/cm²/s with the uni-formity of better than 90% on the 10 cm×10 cm sample.

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MOPR007

Cold and High Power Test of Large Size Magnetic Alloy Core for XiPAF's Synchrotron

59

G.R. Li, X. Guan, W.-H. Huang, X.W. Wang, Z. Yang, H.J. Yaopresenter, H.J. Zeng, S.X. Zheng
TUB, Beijing, People's Republic of China

A compact magnetic alloy (MA) loaded cavity is under development for XiPAF's synchrotron. The cavity contains 6 large size MA cores, each is independently coupled with solid state power amplifier. Two types of MA core are proposed for the project. We have developed a single core model cavity to verify the impedance model and to test the properties of MA cores under high power state. The high power test results are presented and discussed.

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MOPR008

Pressure Profiles Calculation for the CSRm and BRing

62

P. Li, Z. Chai, Z. Dong, X.C. Kang, M. Li, S. Li, W.L. Li, C.L. Luo, R.S. Mao, J. Meng, J.C. Yang, Y.J. Yuan, W.H. Zheng
IMP/CAS, Lanzhou, People's Republic of China

Funding: National Natural Science Foundation of China (Project No. 11305227)
A new large scale accelerator facility is being designed by Institute of Modern Physics (IMP) Lanzhou, which is named as the High Intensity heavy-ion Accelerator Facility (HIAF). This project consists of ion sources, Linac accelerator, synchrotrons (BRing) and several experimental terminals. During the operation of Bring, the heavy ion beams will be easily lost at the vacuum chamber along the BRing when it is used to accumulate intermediate charge state particles. The vacuum pressure bump due to the ion-induced desorption in turn leads to an increase in beam loss rate. In order to accumulate the beams to higher intensity to fulfill the requirements of physics experiments and for better understanding of the dynamic vacuum pressure caused by the beam loss, a dynamic vacuum pressure simulation program has been developed. Vacuum pressure profiles are calculated and compared with the measured data based on the current synchrotron (CSRm). Then the static vacuum pressure profiles of the BRing and one type of pump which will be used in the BRing are introduced in this paper.

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MOPR009

Transverse Beam Splitting Made Operational: Recent Progress of the Multi-Turn Extraction at the CERN Proton Synchrotron

65

A. Huschauer, J.C.C.M. Borburgh, S. Damjanovic, S.S. Gilardoni, M. Giovannozzi, M. Hourican, K. Kahle, G. Le Godec, O. Michels, G. Sterbini
CERN, Geneva, Switzerland
C. Hernalsteens
IBA, Louvain-la-Neuve, Belgium

Following a successful commissioning period, the Multi-Turn Extraction (MTE) at the CERN Proton Synchrotron (PS) has been applied for the fixed-target physics programme at the Super Proton Synchrotron (SPS) since September 2015. This exceptional extraction technique was proposed to replace the long-serving Continuous Transfer (CT) extraction, which has the drawback of inducing high activation in the ring. MTE exploits the principles of non-linear beam dynamics to perform loss-free beam splitting in the horizontal phase space. Over multiple turns, the resulting beamlets are then transferred to the downstream accelerator. The operational deployment of MTE was rendered possible by the full understanding and mitigation of different hardware limitations and by redesigning the extraction trajectories and non-linear optics, which was required due to the installation of a dummy septum to reduce the activation of the magnetic extraction septum. The results of the related experimental and simulation studies, a summary of the 2015 performance analysis, as well as more recent performance improvements are presented in this paper.

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MOPR010

Machine Element Contribution to the Longitudinal Impedance Model of the CERN SPS

71

T. Kaltenbacher, F. Caspers, C. Vollinger
CERN, Geneva, Switzerland

This contribution describes the current longitudinal impedance model of the SPS and studies carried out in order to improve, extend and update it. Specifically, new sources of impedances have been identified, evaluated and included in the model. One finding are low Q and low-frequency (LF; here below 1 GHz) resonances which occur due to enamelled flanges in combination with external cabling e.g. ground loops. These resonances couple to the beam through the gap with enamel coating which creates an open resonator. Since this impedance is important for beam stability in the CERN Proton Synchrotron (PS), RF by-passes were installed on the enamelled flanges, and their significance for the SPS beam is currently under investigation. Simulations, bench and beam measurements were used to deduce model parameters for beam dynamic simulations.

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MOPR011

The SPS 200 MHz TWC Impedance after the LIU Upgrade

76

T. Roggen, R. Calaga, F. Caspers, T. Kaltenbacher, C. Vollinger
CERN, Geneva, Switzerland

Funding: Fellowship co-funded by the European Union as a Marie Curie action (Grant agreement PCOFUND-GA-2010-267194) within the Seventh Framework Programme for Research and Technological Development.
As a part of the LHC Injectors Upgrade project (LIU) the 200 MHz Travelling Wave Cavities (TWC) of the Super Proton Synchrotron (SPS) will be upgraded. The two existing five-section cavities will be rearranged into four three-section cavities (using two existing spare sections), thereby increasing the total voltage from 7 MV (I_RF = 1.5 A) to 10 MV (I_RF = 3.0 A). Projections of the HL-LHC (High Luminosity Large Hadron Collider) era are conceived by the macro-particle simulation code BLonD, that makes use of an impedance model of the SPS, developed from a thorough survey of machine elements. This paper analyses the impedance contribution of the 200 MHz cavities in the two configurations, using electromagnetic simulations. Measurements of the existing cavities in the SPS and a single-section prototype are also presented.

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MOPR012

The New HL-LHC Injection and Transport Protection System

81

F.M. Velotti, W. Bartmann, C. Bracco, M.A. Fraser, B. Goddard, V. Kain, A. Lechner, M. Meddahi
CERN, Geneva, Switzerland

The High-Luminosity LHC (HL-LHC) upgrade represents a challenge for the full chain of its injectors. The aim is to provide beams with a brightness a factor of two higher than the present maximum achieved. The 450 GeV beams injected into the LHC are directly provided by the Super Proton Synchrotron (SPS) via two transfer lines (TL), TI2 and TI8. Such transfer lines are both equipped with a passive protection system to protect the LHC aperture against ultra-fast failures of the extraction and transport systems. In the LHC instead, the injection protection system protects the cold apertures against possible failures of the injection kicker, MKI. Due to the increase of the beam brightness, these passive systems need to be upgraded. In this paper, the foreseen and ongoing modifications of the LHC injection protection system and the TL collimators are presented. Simulations of the protection guaranteed by the new systems in case of failures are described, together with benchmark with measurements for the current systems.

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MOPR014

Corrector Magnets for the CBETA and eRHIC Projects and Other Hadron Facilities*

87

N. Tsoupas, S.J. Brooks, A.K. Jain, F. Méot, V. Ptitsyn, D. Trbojevic
BNL, Upton, Long Island, New York, USA

Funding: Work supported by the U.S. Department of Energy under contract DE- SC0012704.
The Cbeta project[1] is a prototype electron accelerator for the proposed eRHIC project[2]. The electron accelerator is based on the Energy Recovery Linac (ERL) and the Fixed Field Alternating Gradient (FFAG) principles. The FFAG arcs of the accelerator are comprised of one focusing and one defocusing quadrupoles which are designed as Halbach-type permanent magnet quadrupoles[3]. We propose window frame electro-magnets surrounding the Halbach magnets to be used as normal and skew dipoles correctors and quadrupole correctors. We will present results from OPERA-3D calculations of the effect of these corrector magnets on the magnetic field of the main quadrupole magnets and the results will be compared with experimental measurements. We will also discuss applications of permanent magnets with such correctors for hadron beam facilities.
[1] http://arxiv.org/abs/1504.00588
[2] http://arxiv.org/ftp/arxiv/papers/1409/1409.1633.pdf
[3] K. Halbach, NIM 169 (1980) pp. 1-10

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MOPR016

Mitigation of Numerical Noise for Beam Loss Simulations

90

F. Kesting
IAP, Frankfurt am Main, Germany
G. Franchetti
GSI, Darmstadt, Germany

Numerical noise emerges in self-consistent simulations of charged particles, and its mitigation is investigated since the first numerical studies in plasma physics. In accelerator physics, recent studies find an artificial diffusion of the particle beam due to numerical noise in particle-in-cell tracking, which is of particular importance for high intensity machines with a long storage time, as the SIS100 at FAIR or in context of the LIU upgrade at CERN. In beam loss simulations for these projects artificial effects must be distinguished from physical beam loss. Therefore, it is important to relate artificial diffusion to artificial beam loss, and to choose simulation parameters such that physical beam loss is well resolved. As a practical tool, we therefore suggest a scaling law to find optimal simulation parameters for a given maximum percentage of acceptable artificial beam loss.

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MOPR017

Status of the Beam Instrumentation System of CSNS

95

J.L. Sun, J. Pengpresenter, R.Y. Qiu, T. Yang
CSNS, Guangdong Province, People's Republic of China
W.L. Huang, F. Li, P. Li, M. Meng, J.M. Tian, T.G. Xu, Zh.H. Xu, L. Zeng
IHEP, Beijing, People's Republic of China

The first section DTL commissioning of China Spallation Neutron Source (CSNS) project has been successful finished in January, 2016. The H⁻ beam can be accelerated to 21.6 MeV at peak current 18 mA, achieved the design point. Different elements of the beam instrumentation system have been tested during the commissioning, including BPM, CT, FCT, WS, EM, BLM, and corresponding electronics and control systems. High accuracy phase measurement (precision @ ±1°) system has been started into operation. Beam loss monitor (BLM) for low energy, 3 MeV to 21.6 MeV, has been tested too, and got very positive results. For the LRBT, RCS and RTBT, different type wire scanner, BPM, WCM, CT were designed. The monitors fit for the high-radiation environments were considered. All the physical design work has been finished, and being manufactured. Lab test will be started in June and the LINAC commissioning (beam energy up to 80 MeV) will be started in August.

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MOPR018

XAL Applications Development for CSNS Transport Lines

98

Y. Li, Z.P. Li, W.B. Liu
IHEP, Beijing, People's Republic of China
J. Pengpresenter
CSNS, Guangdong Province, People's Republic of China

XAL is an application programming framework initially developed at the Spallation Neutron Source (SNS). It has been employed as a part of control system via con-nection to EPICS to provide application programs for beam commissioning at the China Spallation Neutron Source (CSNS). Several XAL-based applications have been developed for Beam Transport line at CSNS and successfully applied in the MEBT and DTL-1 beam commissioning. These applications will be discussed in this paper.

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MOPR020

Space Charge Effects of High Intensity Beams at BRing

101

J. Li, J.C. Yang
IMP/CAS, Lanzhou, People's Republic of China

Funding: Work supported by NSFC (Grant No. 11475235)
Space charge effects perform one of the main intensity limitations for low energy synchrotron. Large tune spread and crossing resonance stop-bands can hardly be avoided for intensive heavy ion beam at high intensity. Several subjects like Betatron and structure resonance, and tune spread are discussed. Simulations are carried out for 238U³⁴⁺ focusing on emittance and intensity change during RF capture at the injection energy at the booster ring of the High Intensity heavy ion Accelerator Facility (HIAF).
lijie@impcas.ac.cn

Poster MOPR020 [1.157 MB]

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MOPR021

Overview of the ESSnuSB Accumulator Ring

105

M. Olvegård, T.J.C. Ekelöf
Uppsala University, Uppsala, Sweden
E. Benedetto, M. Cieslak-Kowalska, M. Martini, H.O. Schönauer, E.H.M. Wildner
CERN, Geneva, Switzerland

The European Spallation Source (ESS) is a research center based on the world’s most powerful proton driver, 2.0 GeV, 5 MW on target, currently under construction in Lund. With an increased pulse frequency, the ESS linac could deliver additional beam pulses to a neutrino target, thus giving an excellent opportunity to produce a high-performance ESS neutrino Super-Beam (ESSnuSB). The focusing system surrounding the neutrino target requires short proton pulses. An accumulator ring and acceleration of an H⁻ beam in the linac for charge-exchange injection into the accumulator could provide such short pulses. In this paper we present an overview of the work with optimizing the accumulator design and the challenges of injecting and storing 1.10¹⁵ protons per pulse from the linac. In particular, particle tracking simulations with space charge will be described.

Poster MOPR021 [2.731 MB]

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MOPR022

Longitudinal Particle Tracking Code for a High Intensity Proton Synchrotron

110

M. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

We have been developing a longitudinal particle tracking code to design and investigate the beam behavior of the J-PARC proton synchrotrons. The code calculate the longitudinal particle motion with a wake voltage and a space charge effect. The most different point from the other codes is that a synchronous particle motion is calculated from the bending magnetic field pattern. This means the synchronous particle is independent from an acceleration frequency pattern. This feature is useful to check the adiabaticity of the synchrotron. The code also calculates the longitudinal emittance and the filling factor at an rf bucket under the multi-harmonics. We will describe the feature of the code.

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MOPR023

Interpretation of Wire-Scanner Asymmetric Profiles in a Low-Energy Ring

115

M. Cieslak-Kowalska, E. Benedettopresenter
CERN, Geneva, Switzerland

In the CERN PS Booster, wire-scanner profile measurements performed at injection energy are affected by a strong asymmetry. The shape was reproduced with the code pyOrbit, assuming that the effect is due to the beam evolution during the scans, under the influence of space-charge forces and Multiple Coulomb Scattering at the wire itself. Reproducing the transverse profiles during beam evolution allows to use them reliably as input for simulation benchmarking.

Poster MOPR023 [0.482 MB]

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reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR023

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MOPR024

General Formula to Deduce the Space Charge Tune Spread From a Quadrupolar Pick-Up Measurement

120

E. Métral
CERN, Geneva, Switzerland

In 1966, W. Hardt derived the oscillation frequencies obtained in the presence of space charge forces and gradients errors for elliptical beams. Since then, a simple formula is usually used to relate the shift of the quadrupolar mode (obtained from the quadrupolar pick-up) and the space charge tune spread, depending only on the ratio between the two transverse equilibrium beam sizes. However, this formula is not always valid, in particular for machines running close to the coupling resonance Qx = Qy with almost round beams. A new general formula is presented, giving the space charge tune spread as a function of i) the measured shift of the quadrupolar mode, ii) the ratio between the two transverse equilibrium beam sizes and iii) the distance between the two transverse tunes.

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reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR024

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MOPR025

Space Charge Modules for PyHEADTAIL

124

A. Oeftiger
CERN, Geneva, Switzerland
S. Hegglin
ETH, Zurich, Switzerland

Funding: CERN, Doctoral Studentship and EPFL, Doctorate
PyHEADTAIL is a 6D tracking tool developed at CERN to simulate collective effects. We present recent developments of the direct space charge suite, which is available for both the CPU and GPU. A new 3D particle-in-cell solver with open boundary conditions has been implemented. For the transverse plane, there is a semi-analytical Bassetti-Erskine model as well as 2D self-consistent particle-in-cell solvers with both open and closed boundary conditions. For the longitudinal plane, PyHEADTAIL offers line density derivative models. Simulations with these models are benchmarked with experiments at the injection plateau of CERN's Super Proton Synchrotron.

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reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR025

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MOPR026

Space Charge Mitigation With Longitudinally Hollow Bunches

130

A. Oeftiger, S. Hancock, G. Rumolo
CERN, Geneva, Switzerland

Funding: CERN, Doctoral Studentship and EPFL, Doctorate
Hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN's PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.

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MOPR027

Dynamic Beta and Beta-Beating Effects in the Presence of the Beam-Beam Interactions

136

T. Pieloni, X. Buffat, L.E. Medina Medrano, C. Tambasco, R. Tomás
CERN, Geneva, Switzerland
J. Barranco, P. Concalves Jorge, C. Tambasco
EPFL, Lausanne, Switzerland

The Large Hadron Collider (LHC) has achieved correction of beta beat down to better than 5%. The beam-beam interactions at the four experiments result as extra quadrupole error in the lattice. This will produce a change of the β^* at the experiments and a beating along the arcs which for the High Luminosity LHC (HL-LHC) will be very large. Estimations of these effects will be given with the characterisation of the amplitude dependency. A first attempt to correct his beating is also discussed.

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reference for this paper ※ DOI:10.18429/JACoW-HB2016-MOPR027

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MOPR028

CERN PS Booster Longitudinal Dynamics Simulations for the Post-LS2 Scenario

140

D. Quartullo, S.C.P. Albright, E.N. Shaposhnikova, H. Timko
CERN, Geneva, Switzerland

The CERN PS Booster is the first synchrotron in the LHC proton injection chain, it currently accelerates particles from 50 MeV to 1.4 GeV kinetic energy. Several upgrades foreseen by the LHC Injectors Upgrade Program will allow the beam to be accelerated from 160 MeV to 2 GeV after Long Shutdown 2 in 2021. The present RF systems will be replaced by a new one, based on Finemet technology. These and other improvements will help to increase the LHC luminosity by a factor of ten. In order to study beam stability in the longitudinal plane simulations have been performed with the CERN BLonD code, using an accurate longitudinal impedance model and a reliable estimation of the longitudinal space charge. Particular attention has been dedicated to the three main features that currently let the beam go stably through the ramp: Double RF operation in bunch-lengthening mode to reduce the transverse space charge tune spread, exploitation of feedback loops to damp dipole oscillations, and controlled longitudinal emittance blow-up. RF phase noise injection has been considered to study if it could complement or substitute the currently used method based on sinusoidal phase modulation.

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MOPR029

On the Impact of Non-Symplecticity of Space Charge Solvers

146

M. Titze
CERN, Geneva, Switzerland

Funding: German Federal Ministry of Education and Research (BMBF)
To guarantee long-term reliability in the predictions of a numerical integrator, it is a well-known requirement that the underlying map has to be symplectic. It is therefore important to examine in detail the impact on emittance growth and noise generation in case this condition is violated. We present a strategy of how to tackle this question and some results obtained for particular PIC and frozen space charge models.

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MOPR030

Simple Models for Beam Loss Near the Half Integer Resonance with Space Charge

150

C.M. Warsop, D.J. Adams, B. Jones, B.G. Pine
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

The half integer resonance is often used to define the high intensity limit of medium or low energy hadron rings where transverse space charge is significant. However, the mechanism leading to particle loss as beam approaches this resonance, which thus defines the limit, is not clearly understood. In this paper we explore simple models, based on single particle resonance ideas, to see if they describe useful aspects of motion as observed in simulations and experiments of 2D coasting beams on the ISIS synchrotron. Single particle behaviour is compared to 2D self-consistent models to assess when coherent motion begins to affect the single particle motion, and understand the relevance of coherent and incoherent resonance. Whilst the general problem of 2D resonant loss, with non-stationary distributions and non-linear fields is potentially extremely complicated, here we suggest that for a well-designed machine, where higher order pathological loss effects are avoided, a relatively simple model may give valuable insights into beam behaviour and control.

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MOPR031

Development of Physics Models of the ISIS Head-Tail Instability

155

R.E. Williamson, B. Jones, C.M. Warsop
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

ISIS is the pulsed spallation neutron and muon source at the Rutherford Appleton Laboratory in the UK. Operation centres on a rapid cycling proton synchrotron which accelerates 3·10¹³ protons per pulse (ppp) from 70 MeV to 800 MeV at 50 Hz, delivering a mean beam power of 0.2 MW. As a high intensity, loss-limited machine, research and development at ISIS is focused on understanding loss mechanisms with a view to improving operational performance and guiding possible upgrade routes. The head-tail instability observed on ISIS is of particular interest as it is currently a main limitation on beam intensity. Good models of impedance are essential for understanding instabilities and to this end, recent beam-based measurements of the effective transverse impedance of the ISIS synchrotron are presented. This paper also presents developments of a new, in-house code to simulate the head-tail instability observed and includes benchmarks against theory and comparisons with experimental results.

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MOPR033

Beam Acceleration and Transition Crossing in the Fermilab Booster

160

V.A. Lebedev, C.M. Bhat, J.-F. Ostiguy
Fermilab, Batavia, Illinois, USA

To suppress eddy currents, the Fermilab rapid cycling Booster synchrotron has no beam pipe; rather, its combined function dipoles are evacuated, exposing the beam directly to the magnet laminations. This arrangement significantly increases the resistive wall impedance of the dipoles and, in combination with the space charge impedance, substantially complicates longitudinal dynamics at transition. Voltage and accelerating phase profiles in the vicinity of transition are typically empirically optimized to minimize beam loss and emittance growth. In this contribution, we present results of experimental studies of beam acceleration near transition. Using comparisons between observed beam parameters and simulations, we obtain accurate calibrations for the RF program and extract quantitative information about parameters of relevance to the Booster laminated magnets longitudinal impedance model. The results are used to analyze transition crossing in the context of a future 50% increase in beam intensity planned for PIP-II, an upgrade of the Fermilab accelerating complex.

Poster MOPR033 [0.231 MB]

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MOPR034

Suppression of Half-Integer Resonance in Fermilab Booster

164

V.A. Lebedev, A. Valishev
Fermilab, Batavia, Illinois, USA

The particle losses at injection in the FNAL Booster are one of the major factors limiting the machine performance. The losses are caused by motion non-linearity due to direct space charge and due to non-linearity introduced by large values of chromaticity sextupoles required to suppress transverse instabilities. The report aims to address the former - the suppression of incoherent space charge effects by reducing deviations from the perfect periodicity of linear optics functions. It should be achieved by high accuracy optics measurements with subsequent optics correction and by removing known sources of optics perturbations. The study shows significant impact of optics correction on the half-integer stop band with subsequent reduction of particle loss. We use realistic Booster lattice model to understand the present limitations, and investigate the possible improvements which would allow high intensity operation with PIP-II parameters.

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MOPR035

Electron Lens for the Fermilab Integrable Optics Test Accelerator

170

G. Stancari, A.V. Burov, K. Carlson, D.J. Crawford, V.A. Lebedev, J.R. Leibfritz, M.W. McGee, S. Nagaitsev, L.E. Nobrega, C.S. Park, E. Prebys, A.L. Romanov, J. Ruan, V.D. Shiltsev, Y.-M. Shin, J.C.T. Thangaraj, A. Valishev
Fermilab, Batavia, Illinois, USA
D. Noll
IAP, Frankfurt am Main, Germany
Y.-M. Shin
Northern Illinois University, DeKalb, Illinois, USA

Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the US Department of Energy.
The Integrable Optics Test Accelerator (IOTA) is a research machine currently being designed and built at Fermilab. The research program includes the study of nonlinear integrable lattices, beam dynamics with self fields, and optical stochastic cooling. One section of the ring will contain an electron lens, a low-energy magnetized electron beam overlapping with the circulating beam. The electron lens can work as a nonlinear element, as an electron cooler, or as a space-charge compensator. We describe the physical principles, experiment design, and hardware implementation plans for the IOTA electron lens.

Poster MOPR035 [5.399 MB]

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MOPR036

Spin Tracking of Polarized Protons in the Main Injector at Fermilab

173

M. Xiao
Fermilab, Batavia, Illinois, USA
C. Aldred, W. Lorenzon
Michigan University, Ann Arbor, Michigan, USA

The Main Injector (MI) at Fermilab currently produces high-intensity beams of protons at energies of 120 GeV for a variety of physics experiments. Acceleration of polarized protons in the MI would provide opportunities for a rich spin physics program at Fermilab. To achieve polarized proton beams in the Fermilab accelerator com-plex, shown in Fig.1.1, detailed spin tracking simulations with realistic parameters based on the existing facility are required. This report presents studies at the MI using a single 4-twist Siberian snake to determine the depolariz-ing spin resonances for the relevant synchrotrons. Results will be presented first for a perfect MI lattice, followed by a lattice that includes the real MI imperfections, such as the measured magnet field errors and quadrupole misa-lignments. The tolerances of each of these factors in maintaining polarization in the Main Injector will be discussed.

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