MOPAB —  Poster Session   (10-Nov-14   16:10—18:00)
Chair: Y. Zhang, FRIB, East Lansing, Michigan, USA

Paper	Title	Page
MOPAB02	Progress in the Upgrade of the CERN PS Booster Recombination	24
	J.L. Abelleira, W. Bartmann, J. Borburgh, E. Bravin, U. Raich CERN, Geneva, Switzerland
	The CERN PS Booster recombination lines (BT) will be upgraded following the extraction energy increase foreseen in 2018 and meant to reduce the direct space-charge tune shift in the PS injection for the future HL-LHC beams. Henceforth the main line elements, recombination septa, quadrupoles and dipoles must be scaled up to this energy. An increase in the beam rigidity by a factor 1.3 would require the same factor in the field integral of the septa, ∫Bdl, in order to bend the same angle and preserve the present recombination geometry, which is one of the main upgrade constraints. This paper describes the new optics, in particular in the new and longer septa. In addition we consider the upgrade of the so called BTM line that brings the beam to the external dump and where emittance measurements are taken thanks to three pairs of grids. The new proposed optics has also the advantage to simplify the design of the new dipoles. Here we study this new optics and the issues related to the emittance measurement at the new higher energy.
MOPAB04	An Overview of the Preparation and Characteristics of the ISIS Stripping Foil	29
	H. V. Smith, B. Jones STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	The ISIS facility at the Rutherford Appleton Laboratory is a pulsed neutron and muon source, for materials and life science research. H− ions are injected into an 800 MeV, 50 Hz rapid cycling synchrotron from a 70 MeV linear accelerator, over ~130 turns by charge exchange injection. Up to 3·1013 protons per pulse can be accelerated, with the beam current of 240 μA split between the two spallation neutron targets. The 40 × 120 mm aluminium oxide stripping foils used for injection are manufactured on-site. This paper gives an overview of the preparation and characteristics of the ISIS foils, including measurements of foil thickness and elemental composition. Consideration is also given to the beam footprint on the foil and how this could be optimised.
MOPAB05	Global Optics Correction for Low Energy RHIC Run	34
	C. Liu, K.A. Drees, A. Marusic, M.G. Minty, C. Montag BNL, Upton, Long Island, New York, USA
	Funding: The work was performed under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. There has been increasing interest in low energy run in RHIC to study the QCD phase diagram and search for the critical point. The machine optics is one of the critical pieces for a successful low energy run since it affects the luminosity and its lifetime. Despite the difficulties of taking optics measurement data, progress has been made in recent years to analyze and correct the global optics errors. The analysis technique and specific exception handling, and the results of optics correction for low energy runs will be presented in the report.
MOPAB08	Longitudinal Dynamics Simulation at Transition Crossing in RHIC with New Landau Cavity	37
	C. Liu, M. Blaskiewicz, J.M. Brennan, K. Mernick, M.G. Minty, C. Montag, K.S. Smith BNL, Upton, Long Island, New York, USA
	Funding: The work was performed under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. At RHIC, heavy ion beams cross transition energy during acceleration to energies required by the physics programs. In the past, to battle longitudinal instabilities, a Landau cavity was turned on just after acceleration through transition energy. The Landau cavity with modified frequency will be implemented before beam crosses transition in Run-14. Longitudinal dynamics with this new configuration have been simulated to optimize the phase and amplitude of the Landau cavity. We will present simulation results in the report.
MOPAB10	Beam-based Performance of the CERN PS Transverse Feedback	40
	G. Sterbini, A. Blas, S.S. Gilardoni CERN, Geneva, Switzerland
	The CERN PS transverse damper is a flexible wideband system to damp injection coherent oscillations, inter and intra-bunch transverse instabilities at different energies along the cycle, to perform controlled emittance blow-up and to serve as abort cleaning device. In this paper we summarise some beam-based observations of the CERN PS transverse feedback performance and compare them with the expected results.
MOPAB11	Transverse Decoherence of Ion Bunches with Space Charge and Feedback System	45
	I. Karpov TEMF, TU Darmstadt, Darmstadt, Germany O. Boine-Frankenheim, V. Kornilov GSI, Darmstadt, Germany
	The transverse decoherence of the bunch signal after an initial bunch displacement is an important process in synchrotrons and storage rings. It can be useful, for the diagnostic purposes, or undesirable. Collective bunch oscillations can appear after the bunch-to-bucket transfer between synchrotrons and can lead to the emittance blow-up. In order to preserve the beam quality and to control the emittance blow-up, transverse feedback systems (TFS) are used. But, TFS operation can also lead to emittance blow-up due to imperfections (noise, bandwidth limitation, time delay errors), which also depends on the TFS settings. In heavy ion and proton beams, like in SIS100 synchrotron of the FAIR project, transverse space charge strongly modify decoherence. The resulting transverse bunch decoherence and beam blow-up is due to a combination of the lattice settings (like chromaticity), nonlinearities (residual or imposed by octupole magnets), space-charge, and the TFS. We study these effects using particle tracking simulations with the objective of correct combinations for a controlled beam blow-up.
MOPAB12	Slip-stacking Dynamics and the 20 Hz Booster	50
	J.S. Eldred Indiana University, Bloomington, Indiana, USA J.S. Eldred, R.M. Zwaska Fermilab, Batavia, Illinois, USA
	Slip-stacking is an accumulation technique used at Fermilab since 2004 which nearly doubles the proton intensity. The Proton Improvement Plan II intensity upgrades require a reduction in slip-stacking losses by approximately a factor of 2. We study the single-particle dynamics that determine the stability of slip-stacking particles. We introduce universal area factors to calculate the available phase space area for any set of beam parameters without individual simulation. We show the particle loss as a function of time. We calculate the injection efficiency as a function of longitudinal emittance and aspect-ratio. We demonstrate that the losses from RF single particle dynamics can be reduced by a factor of 4-10 (depending on beam parameters) by upgrading the Fermilab Booster from a 15-Hz cycle-rate to a 20-Hz cycle-rate. We recommend a change in injection scheme to eliminate the need for a greater momentum aperture in the Fermilab Recycler.
MOPAB17	RMS Emittance Measures for Solenoid Transport and Facitlity for Rare Isotope Beams Front-End Simulations	57
	S.M. Lund, G. Pozdeyev, H.T. Ren, Q. Zhao FRIB, East Lansing, Michigan, USA
	Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 and the National Science Foundation under Grant No. PHY-1102511. Measurement of beam phase-space area via rms emittances in solenoid focusing channels with linear x-y coupling is complicated relative to transport channels with decoupled plane focusing. This stems from correlated azimuthal flow of the beam induced by the coupled focusing influencing how the thermal component of the flow should be measured. This is exacerbated when the beam has finite canonical angular momentum – as is the case for beams born in a magnetic field in ECR-type sources. In this study, simple measures of rms emittance for use in solenoid transport for beams with canonical angular momentum are motivated and overviewed. Emphasis is placed on simple to interpret emittance measures which reduce to familiar forms for decoupled plane motion. These emittances are applied in Warp PIC simulations of the near-source region of the FRIB linac front-end. In these simulations, a multi-species heavy-ion dc beam emerging from an ECR source are simulated primarily in transverse slice mode using a realistic lattice description. Emittance growth due to nonlinear applied fields, space-charge, and partial neutralization is analyzed including the influence of net canonical angular momentum.
MOPAB18	An ESS Linac Collimation Study	62
	R. Miyamoto, M. Eshraqi ESS, Lund, Sweden H.D. Thomsen ISA, Aarhus, Denmark
	The European Spallation Source (ESS) is planned in Lund, Sweden, and will be a neutron source based on a proton linac with an unprecedented 5 MW beam power. Mitigation of beam losses is the most crucial challenge in beam physics for such a high power proton linac and collimation systems are planned in sections of the medium and high energy beam transport (MEBT and HEBT). A preliminary study of the collimation systems was presented in the previous time of this workshop but the linac design went through a significant revision since then. The system to expand the beam for the neutron target, located in the HEBT, was changed from one based on nonlinear magnets to a raster system and this change particularly had a significant impact on the demand on the collimation systems. This paper presents an updated beam dynamics study of the collimation systems for the present layout of the ESS Linac.
MOPAB19	Space-Charge Compensation of Intense Ion Beams by Nonneutral Plasma Columns	67
	K. Schulte, M. Droba, O.K. Kester, S. Klaproth, O. Meusel, D. Noll, U. Ratzinger, K. Zerbe IAP, Frankfurt am Main, Germany O.K. Kester GSI, Darmstadt, Germany
	Gabor lenses were conceived to focus a passing ion beam using the electrical field of a confined nonneutral plasma column. Beside its application as focusing device, in Gabor lenses space-charge effects can be studied in detail. The influence of the electron distribution on emittance and space-charge dominated ion beams was investigated in beam transport experiments*. In this contribution we want to emphasize one result of these experiments. The measurements indicated a strong contribution of secondary electrons on beam dynamics. Secondary electrons are produced within the transport channel, particularly by interaction of the beam with the surface of the slit-grid emittance scanner. This might lead to an increase of the filling degree and to an improved focusing performance of the lens. Assuming that the loss and production rates within the lens volume and the transport channel determine the equilibrium state of the nonneutral plasma column, the electron cloud was characterized as a function of the external fields and the residual gas pressure in small-scale table top experiments. In this contribution experimental results will be presented in comparison with numerical simulations. * K. Schulte, “Studies on the focusing performance of a Gabor lens depending on nonneutral plasma properties”, PhD thesis, 2013.
MOPAB21	A Novel Code with High-order Adaptive Dynamics to Solve the N-body Problem	70
	S. Abeyratne, B. Erdelyi, H.D. Schaumburg Northern Illinois University, DeKalb, Illinois, USA B. Erdelyi ANL, Argonne, USA
	Although there are several publicly available algorithms to model the behavior of natural systems such as the N-body system, limited computing power hinders the attempt to simulate them efficiently. With the improvement of high performance computing, scientists will be able to run simulations at an unprecedented scale in the future. Therefore, it is necessary to develop new algorithms and data structures to harness the power of high performance computing. In this paper we show a newly developed code, particles’ high order adaptive dynamics (PHAD), to serve future computing demands. We use Fast Multipole Method (FMM) to calculate the interactions among charged particles. We use the Strang splitting technique to reduce the number of FMM calls and enhance the efficiency. Picard iterations-based novel integrators are employed to achieve very high accuracies. Electron cooling in the proposed Electron Ion Collider (EIC) has been identified as a potential testing environment for PHAD.
MOPAB23	Resonance Structures in the Impedance of a Ceramic Break and the Measured Results	74
	Y. Shobuda JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan Y.H. Chin, K. Takata KEK, Ibaraki, Japan T. Toyama J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	Recently, we have developed a new theory to evaluate longitudinal and transverse impedances of any size of ceramic break sandwiched between metal chambers. The theory successfully reproduces the resonance structures in the impedance due to trapped modes inside the ceramic break. The comparisons between the theoretical and the simulation results such as ABCI and CST Studio show excellent agreements, indicating that they can be used as a good benchmark test for accuracy of simulation codes. To demonstrate the existence of such resonances, the transverse impedance of the ceramic break is measured using the wire-method. The measurement results reproduce the simulations well. The theory is particularly useful for the evaluation of the impedance of the ceramic break with titanium nitride coating.
MOPAB24	Identification of Intra-bunch Transverse Dynamics for Feedback Control Purposes at CERN Super Proton Synchrotron	79
	O. Turgut, J.D. Fox, C.H. Rivetta SLAC, Menlo Park, California, USA W. Höfle CERN, Geneva, Switzerland S.M. Rock Stanford University, Stanford, California, USA
	Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP). We present methods for parameter estimation of intra-bunch transverse beam dynamics. The dynamics is represented via reduced order linear models. These models are useful in beam monitoring and in the design of feedback controllers to stabilize intra-bunch transverse instabilities. The effort is motivated by the plans to increase currents in the Super Proton Synchrotron as part of the HL-LHC upgrade where feedback methods could control instabilities and allow greater freedom in machine lattice parameters. Identification algorithms use subspace methods to compute a discrete multi-input multi-output (MIMO) representation of the nonlinear dynamics. We use macro particle simulation data (CMAD and HEADTAIL) and SPS machine measurements as the source of dynamics information for the identification of beam dynamics. Reduced models capture the essential dynamics of the beam motion or instability at a particular operating point, and can then be used analytically to design optimal feedback controllers. The robustness of the model parameters against noise and external excitation signals is studied, as is the effect of the MIMO model order on the accuracy of the identification algorithms.
MOPAB26	Study of Beam Dynamics in Linear Paul Traps	84
	D.J. Kelliher, S. Machida, C.R. Prior, S.L. Sheehy STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
	The Hamiltonian governing the dynamics in a Linear Paul Trap (LPT) is identical in form to that of a beam in a focusing channel. This similarity, together with the LPT’s flexibility, compactness and low cost make it a useful tool for the study of a wide range of accelerator physics topics. Existing work has focused on high intensity collective effects as well as, more recently, the study of integer resonance crossing in the low intensity regime. A natural extension of this work is to investigate space charge effects of intense beams in more realistic lattices to directly inform accelerator design and development. For this purpose we propose to construct a modified Paul Trap specifically for these studies. Among other features, it is envisaged that this new LPT should be able to model non-linear elements and a wider range of lattice configurations. This work will be undertaken in collaboration with Hiroshimi University.
MOPAB27	Characterisation of the KURRI 150 MeV FFAG and Plans for High Intensity Experiments	89
	S.L. Sheehy, D.J. Kelliher, S. Machida, C.R. Prior, C.T. Rogers STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
	Fixed field alternating gradient (FFAG) accelerators hold a lot of promise for high power operation due to their high repetition rate and strong focusing optics. However, to date these machines have not been operated with high intensity beams. Since November 2013 an experimental collaboration has been underway to characterise the 150 MeV proton FFAG at KURRI, Japan. Here we report on the results of characterisation experiments and discuss plans for further experiments in the high intensity regime.
MOPAB29	Efficient 3D Poisson Solvers or Space-charge Simulation	94
	J. Qiang LBNL, Berkeley, California, USA
	Funding: This work was partially supported by the U. S. Department of Energy under contract No. DE-AC02- 05CH11231. Three-dimensional Poisson solver plays an important role in the self-consistent space-charge simulation. In this paper, we present several efficient 3D Poisson solvers inside an open rectangular conducting pipe for space-charge simulation. We describe numerical algorithm of each solver, show comparative results for these solvers and discuss the pros and cons associated with each solver.
MOPAB30	A Multi-particle Online Beam Dynamics Simulator for High Power Ion Linac Operations	99
	X. Pang, S.A. Baily, L. Rybarcyk LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by DOE under contract DE-AC52-06NA25396 During high-power ion-linac operations, the low-beam-loss operational settings are typically extrapolated from the low-power mode through highly subjective empirical adjustments. Existing simulation tools in accelerator control rooms are too simplified to handle the complex beam dynamics and the strong space charge effects, therefore providing no useful guidance for the high power beam tuning. We have been developing a GPU accelerated multi-particle beam dynamics simulator to try to bridge the gap. By combining the GPU technology and the multi-particle beam dynamics simulation algorithms, we have created a realistic beam simulator that is both accurate and fast enough to be useful in accelerator control rooms. Once connected to the EPICS control system, the simulator can rapidly respond to any control set point changes and predict beam properties along an ion linac in pseudo real time. Its applications include virtual diagnostics during operations, test-bed for new operation/control schemes, operation optimization and operator training.
MOPAB31	Space Charge Map Extraction and Analysis in a Differential Algebraic Framework	103
	A.J. Gee, B. Erdelyi Northern Illinois University, DeKalb, Illinois, USA B. Erdelyi ANL, Argonne, USA
	Funding: This work was supported in part by the U.S. Department of Energy, Office of High Energy Physics, under Contract Nos. DE-FG02-08ER41532 and DE-SC0011831, with Northern Illinois University. Space charge is a leading concern in high-intensity beams, causing effects such as emittance growth, beam halos, etc. As the need for high-intensity beams spreads, the demand for efficient space charge analysis grows. We developed a self consistent space charge simulation method for this purpose [*]. In order to facilitate space charge analysis, we implemented a method that allows space charge map extraction and analysis from any tracking method [*,**]. We demonstrate the method by calculating the transverse space charge. We compare the method of moments and the fast multipole method as the tracking methods employed in the transfer map extraction process. We show results from analysis of the raw map elements as well as quantities obtained from normal forms. [*] Erdelyi, Nissen, and Manikonda. A Differential Algebraic Method for the Solution of the Poisson Equation for Charged Particle Beams. [**] Berz. Modern Map Methods in Particle Beam Physics.
MOPAB35	Beam Dynamics Influence from Quadrupole Components in FRIB Quarter Wave Resonators	108
	Z.Q. He, Z. Liu, J. Wei, Y. Zhang, Z. Zheng FRIB, East Lansing, Michigan, USA
	Funding: The work is supported by the U.S. National Science Foundation under Grant No. PHY-11-02511, and the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661. Non-axisymmetric RF cavities, such as quarter-wave resonators (QWRs), can produce axially asymmetric multipole field components that can influence beam dynamics. For example, dipole components can cause beam steering, an effect that has been well known to the community since 2001. However, higher order multipole field components, such as quadrupole components, which have potential influence on beam dynamics, have never received enough attention yet. In this paper, we choose FRIB QWRs as an example and quadrupole components are extracted by multipole expansion. Then, influence of quadrupole components on a single cavity is studied using thin lens model. After that, the influence of quadrupole components on a whole FRIB linac segment one is studied, and effects such as transverse profile ovalization and blow up of beam size are witnessed. Lastly, a possible way of quadrupole components compensation for FRIB driving linac is discussed.
MOPAB38	Simulations of the Head-tail Instability on the ISIS Synchrotron	113
	R.E. Williamson, D.J. Adams, B. Jones, C.M. Warsop STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom V. Kornilov GSI, Darmstadt, Germany
	ISIS is the pulsed spallation neutron and muon source at the Rutherford Appleton Laboratory in the UK. Operation is centred on a loss limited 50 Hz proton synchrotron which accelerates 3·1013 protons per pulse (ppp) from 70 MeV to 800 MeV, delivering a mean beam power of 0.2 MW. Present studies are focussed on key aspects of high intensity beam dynamics with a view to increasing operational intensity, understanding loss mechanisms and identifying possible upgrade routes. Of particular interest is the head-tail instability observed on ISIS, which is currently the main limitation on beam intensity. This paper presents initial simulations using HEADTAIL to compare with experimental data taken on the ISIS synchrotron. The details and assumptions of the impedance model and simulations are discussed. Plans for future head-tail measurements, simulations and analysis are outlined.
MOPAB39	Image Fields in the Rectangular Vacuum Vessels of the ISIS Synchrotron	118
	B.G. Pine, C.M. Warsop STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	ISIS is the pulsed spallation neutron source based at Rutherford Appleton Laboratory in the UK. Operation is based on a 50 Hz, 800 MeV proton synchrotron, accelerating up to 3·1013 protons per pulse, which provides beam to two target stations. Space charge effects contribute significantly to beam loss. Fields from the intense beam interact strongly with their environment. At ISIS the vacuum vessel is rectangular and profiled to follow the shape of the design beam envelope. Past studies have suggested that closed orbit induced image fields may contribute to beam loss under certain conditions. Image fields for parallel plate and rectangular geometries are reviewed, in particular their expansion as power series is determined. A simulation tool has been developed for particle tracking. The code contains both FFT and FEA field solvers, which have been used here to test the power series expansions for centred and off-centred beams. These expansions are then used to determine driving terms for the transverse beam motion. Of particular interest for ISIS is the resonant behaviour of beams with a harmonic closed orbit, which can be compared with the output of beam tracking simulations.
MOPAB40	Studies of Loss Mechanisms Associated with the Half Integer Limit on the ISIS Ring	123
	C.M. Warsop, D.J. Adams, B. Jones, B.G. Pine, H. V. Smith, C.C. Wilcox, R.E. Williamson STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK. The facility centres on an 800 MeV rapid cycling proton synchrotron, which provides 0.2 MW of beam power operating at high levels of transverse space charge (peak incoherent tune shift ~ 0.5), but with low loss. Half integer resonance is considered to be a main driver for loss that limits the intensity in high power, medium energy proton rings like ISIS. However, the detailed mechanisms causing loss as the half integer limit is approached are not well understood, particularly in the context of a real machine. In this paper we report progress on experiments on the ISIS synchrotron inducing half integer loss, comparing with detailed simulations and attempts to relate these to simplified theoretical and simulation models. Effects of longitudinal motion on growth mechanisms, e.g. in coasting, “frozen” bunched and rapid cycling bunched beams are discussed, as is how these losses might be minimised and thus the real space charge limit effectively increased.
MOPAB41	Feasibility Study of a Novel, Fast Read-out System for an Ionization Profile Monitor Based on a Hybrid Pixel Detector	128
	O. Keller, B. Dehning, M. Sapinski, L.S. Swann CERN, Geneva, Switzerland
	The ability to continuously monitor the transverse beam size is one of the priorities for the upgrade and consolidation of the CERN Proton Synchrotron for the High Luminosity LHC era. As well as providing an average beam size measurement throughout the acceleration cycle, the requirements also cover bunch-by-bunch measurements of up to 72 bunches with a bunch spacing of 25 ns within 1 ms. An ionization profile monitor with a hybrid pixel detector read-out is therefore being investigated as a possible candidate to provide such measurements. In this contribution the concept, based on a Timepix chip, is presented along with first laboratory measurements showing the imaging of low-energy electrons in a vacuum.
MOPAB42	Investigation of the Effect of Beam Space-charge on Electron Trajectories in Ionization Profile Monitors	133
	D.M. Vilsmeier, B. Dehning, M. Sapinski CERN, Geneva, Switzerland
	The correct measurement of beam size using an ionization profile monitor relies on the confinement of electron trajectories from their source to the electron-sensitive detector. This confinement is provided by a magnetic field aligned with electric extraction field. As the initial electron velocities are boosted by the presence of a high-charge density beam, the value of the magnetic field depends on both the beam size and on the charge density. If the magnetic field is not strong enough a deformation of the observed beam profile occurs. In this paper the results of a study of electron trajectories in the presence of high charge density beams is presented along with an estimation of the required magnetic field for various scenarios. A correction procedure for compensating any residual distortions in the measured profile is also discussed.
MOPAB43	Studies on Heavy Ion Losses from Collimation Cleaning at the LHC	138
	P.D. Hermes, R. Bruce, J.M. Jowett, S. Redaelli, B. Salvachua, G. Valentino, D. Wollmann CERN, Geneva, Switzerland
	The LHC collimation system protects superconducting magnets from beam losses. By design, it was optimized for the high-intensity proton challenges but so far provided adequate protection also during the LHC heavy-ion runs with 208 Pb 82+ ions up to a beam energy of 4 Z TeV. Ion beam cleaning brings specific challenges due to different physical interactions with the collimator materials and might require further improvements for operation at 7 Z TeV. In this article, we study heavy-ion beam losses leaking out of the LHC collimation system, both in measurement and simulations. The simulations are carried out using both ICOSIM, with a simplified ion physics model implemented, and SixTrack, including more detailed starting conditions from FLUKA but without including online scattering in subsequent collimator hits. The results agree well with measurements overall, although some discrepancies are present. The reasons for the discrepancies are investigated and, on this basis, the requirements for an improved simulation tool are outlined.
MOPAB44	Beam Halo Measurement Using a Combination of a Wire Scanner Type Beam Scraper and Some Beam Loss Monitors in J-PARC 3-GeV RCS	143
	M. Yoshimoto, H. Harada, M. Kinsho, K. Okabe JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	Transverse beam halo is one of the most important beam parameters due to limit the performance of the high intensity beam accelerator. Therefore, the transverse beam halo measurement is required to increase the beam power of the J-PARC 3-GeV RCS. New beam halo monitor, which is combined a wire type beam scraper and some beam loss monitors, are installed in the extraction beam transport line. In order to use some beam loss monitors with a plurality of different sensitivities, it's ultra wide dynamic range can be achieved and beam profile including both of the beam core and halo can be obtained.
MOPAB46	Proposed Varying Amplitude Raster Pattern to Uniformly Cover Target for the Isotope Production Facility (IPF) at LANSCE	148
	J.S. Kolski LANL, Los Alamos, New Mexico, USA
	The Isotope Production Facility (IPF) at LANSCE produces medical isotopes strontium-82 and germanium-68 by bombarding rubidium chloride and gallium metal targets respectively with a 100 MeV proton beam, 230 uA average current. Rastering the proton beam is necessary to distribute heat load on the target and target window, allowing higher average beam current for isotope production. Currently, we use a simple circular raster pattern with constant amplitude and frequency. The constant amplitude raster pattern does not expose the target center to beam and few isotopes are produced there. We propose a raster pattern with varying amplitude to increase isotope production at the target center, achieve uniform beam flux over the target, and expose more of the target surface to beam heating. Using multiparticle simulations, we discuss the uniformity of target coverage using the proposed varying amplitude raster pattern, compare with the constant amplitude raster pattern currently used, and consider dependencies on transverse beam size, beam centroid offset, and macropulse length and repetition rate.
	Poster MOPAB46 [7.847 MB]
MOPAB47	Simulation of a New Beam Current Monitor Under Heavy Heat Load	151
	J.L. Sun, P.-A. Duperrex PSI, Villigen PSI, Switzerland
	Funding: "The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement n.°290605 (PSIFELLOW/ COFUND)" At the Paul Scherrer Institute (PSI), the High Intensity Proton Accelerator (HIPA) feeds a spallation source target with protons. A beam current monitor installed 8 meters downstream from the target is heated by the scattered particles from the target. This thermal load on the monitor causes the resonance frequency to drift much more than expected. A novel new beam current monitor using graphite has been developed. In order to have a good understanding of its performance, the simulation software ANSYS has been used to carry out thermal and high frequency simulations. With this software, it was possible to perform a detailed design of the thermal self-compensation scheme and to check the structural stability of the whole system. In this paper, simulation results are presented to show that frequency and sensitivity drifts can be reduced to 8 kHz from previous 730 kHz when realistic operating conditions are assumed.
MOPAB48	Design of a New Beam Current Monitor Under Heavy Heat Load	154
	J.L. Sun, P.-A. Duperrex, G. Kotrle PSI, Villigen PSI, Switzerland
	Funding: The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement n.°290605 (PSI-FELLOW/COFUND) At the Paul Scherrer Institute (PSI), a 590 MeV 50 MHz High Intensity Proton Accelerator (HIPA) has been operated for many years at 2.2 mA / 1.3 MW and it will be soon upgraded to 3 mA / 1.8 MW. A spallation source target is driven from the HIPA. Downstream from this target is a beam current monitor, called MHC5. The thermal load in MHC5 induced by the scattered particles from the target causes the resonance frequency of the current monitor to drift. Even with an active cooling system, the drift remains a problem. A new beam current monitor has been designed to overcome this shortcoming. The mechanical design of the new monitor has been completed and manufacturing will start soon. A novel feature is the use of graphite for the resonator cavity to give thermal self-compensation, structural stability and improved thermal load distribution. The design and the preliminary lab test results are presented in this paper.
MOPAB51	Beam Dynamics Study for J-PARC Main Ring by Using the 'Pencil' and Space-charge Dominated Beam: Measurements and Simulations	157
	A.Y. Molodozhentsev, S. Igarashi, Y. Sato, J. Takano KEK, Ibaraki, Japan
	J-PARC Main Ring (MR) study has been performed during 2013-2014 to optimize the machine performance. As the result of this activity the ‘200 kW’ proton beam has been successfully extracted from MR into the ‘Neutrino’ beamline. Total particle losses, localized at the MR collimation section, have been estimated as 150 W. The 'low-losses' MR operation has been achieved after optimization the injection process, setting the MR RF system, dynamic control of the chromaticity and compensation the linear coupling resonance. In frame of this report we will discuss the obtained experimental results and compare it with simulations, performed extensively for different machine operation scenario, including the 'pencil' low intensity beam and the space-charge dominated beam. The obtained results demonstrate agreement between simulations and measurements for emittance evolution and losses for different cases. The developed MR computational model will be used to optimize the machine performance for the ‘MegaWatt’ MR operation scenario with limited losses. The modeling of the beam dynamics for these cases has been performed by using the ‘PTC-ORBIT’ combined code, installed on the KEK supercomputer.