IPAC2011 - List of Keywords (beam-losses)

Paper	Title	Other Keywords	Page
MOXBA01	J-PARC Beam Commissioning Progress	injection, linac, extraction, vacuum	6
	H. Hotchi JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	The J-PARC is a multi-purpose proton accelerator facility amiming at MW-class output beam power, consisting of a 400 MeV H⁻ linac, a 3-GeV RCS, a 50-GeV MR (Main Ring) and three experimental facilities, the MLF (materials and life science experimental facility), the HD (hadron experimental hall) and the NU (neutrino beam line). The J-PARC beam commissioning started in November 2006 from the linac to the downstream facilities. The current output beam power from the RCS to the MLF users is 210 kW, and the MR delivers 145 kW beam to the NU by fast extraction and a few kW beam to the HD by slow extraction. In this talk, we present a current status of the J-PARC beam commissioning, in which a recent progress in the course of the RCS beam power ramp-up scenario will be described in more detail. This talk will focus on the issues (including beam dynamics), challenges, solutions, and lessons learned during the commissioning and user operation of J-PARC and future plans.
	Slides MOXBA01 [2.615 MB]

MOODB02	RF Modeling Plans for the European Spallation Source	cavity, HOM, electron, linac	56
	S. Molloy, M. Lindroos, S. Peggs ESS, Lund, Sweden R. Ainsworth Royal Holloway, University of London, Surrey, United Kingdom R.J.M.Y. Ruber Uppsala University, Uppsala, Sweden
	The European Spallation Source (ESS) will be the world's most powerful next generation neutron source. The ESS linac is designed to accelerate highly charged bunches of protons to a final energy of 2.5 GeV, with a design beam power of 5 MW, for collision with a target used to produce the high neutron flux. In order to achieve this several stages of RF acceleration are required, each using a different technology. The high beam current and power require a high degree of control of the accelerating RF, and the specification that no more than 1 W/m of losses will be experienced means that the excitation and decay of the HOMs must be very well understood. Experience at other high power machines also implies that an understanding of the generation and subsequent trajectories of any field-emitted electrons should be understood. Thermal detuning of the HOM couplers due to multipacting is a serious concern here. This paper will outline the RF modeling plans - including the construction of mathematical models, simulations of HOMs, and multipacting - during the current Accelerator Design Update phase, and will discuss several of the more important issues for ESS.
	Slides MOODB02 [48.641 MB]

MOPC089	RF Simulations for the QWR Cavities of PIAVE-ALPI	cavity, simulation, ion, linac	283
	M. Comunian, F. Grespan, A. Palmieri INFN/LNL, Legnaro (PD), Italy
	The PIAVE-ALPI linac is composed of several families of QWR cavities. In order to have a thorough description of the accelerator in terms of beam dynamics, a detailed field mapping of the accelerating cavities is necessary, including non-linear behavior of the off-axis fields, as well as the steering and dispersion effects due to transverse components. For such a purpose, a set of RF simulation was accomplished, with the codes HFSS and COMSOL. The details about these simulations and the main outcomes and results will be described in this article.

MOPO011	The First 1 1/2 Years of TOTEM Roman Pot Operation at LHC	alignment, controls, HOM, scattering	502
	M. Deile, G.H. Antchev, R.W. Assmann, I. Atanassov, V. Avati, J. Baechler, R. Bruce, M. Dupont, K. Eggert, B. Farnham, J. Kaspar, F. Lucas Rodríguez, J. Morant, H. Niewiadomski, X. Pons, E. Radermacher, S. Ravat, F. Ravotti, S. Redaelli, G. Ruggiero, H. Sabba, M. Sapinski, W. Snoeys, G. Valentino, D. Wollmann CERN, Geneva, Switzerland R. Appleby UMAN, Manchester, United Kingdom
	Since the LHC running season 2010, the TOTEM Roman Pots (RPs) are fully operational and serve for collecting elastic and diffractive proton-proton scattering data. Like for other moveable devices approaching the high intensity LHC beams, a reliable and precise control of the RP position is critical to machine protection. After a review of the RP movement control and position interlock system, the crucial task of alignment will be discussed.

MOPS002	Mitigation of Space Charge and Nonlinear Resonance Induced Beam Loss in SIS100	resonance, space-charge, acceleration, simulation	589
	G. Franchetti GSI, Darmstadt, Germany
	The control of beam loss in SIS100 is essential for avoiding vacuum instability and guarantee the delivery of the foreseen beam intensity. On the other hand simulations show that the simultaneous presence of space charge and lattice resonances creates during 1 second cycle a progressive beam loss exceeding the limit of 5%. Until now the mechanism of periodic resonance crossing were suspected to be, in conjunction with pure dynamic aperture effects, at the base of the beam loss. In this proceeding we present the state of the art in the beam loss prediction and we prove that the periodic resonance crossing is the deteriorating mechanism, and show that the compensation of a relevant resonance intercepting the space charge tune spread sensibly mitigate the beam loss. A short discussion on beam loss during acceleration is addressed as well.

MOPS005	Beam Dynamics Simulations of J-PARC Main Ring for Upgrade Plan of Fast Extraction Operation	simulation, injection, proton, power-supply	598
	Y. Sato, K. Hara, S. Igarashi, T. Koseki, K. Ohmi, C. Ohmori, M. Tomizawa KEK, Ibaraki, Japan H. Hotchi JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	Beam loss simulations under space charge effects are necessary to seek higher intensity proton beams. This paper presents simulations for fast extraction operation of Japan Proton Accelerator Research Complex (J-PARC) Main Ring. For upgrade plan, increasing protons per bunch and making higher repetition pattern are considered. Their optimal balance is discussed to minimize beam losses for aimed beam power considering space charge effects. We found that to optimize RF voltage pattern is a strong key to reduce beam losses for higher repetition. As benchmark works, we compare our simulations with the measured beam loss in our past operation.

MOPS014	Tune and Space Charge Studies for High-brightness and High-intensity Beams at CERN PS	resonance, emittance, space-charge, injection	625
	S.S. Gilardoni, S. Aumon, J. Brenas, P. Freyermuth, A. Huschauer, R. Maillet, E. Matli, R.R. Steerenberg, B. Vandorpe CERN, Geneva, Switzerland E. Benedetto National Technical University of Athens, Zografou, Greece
	The current 1.4 GeV CERN PS injection energy limits the maximum intensity required by the future High-Luminosity LHC. The bare-machine large chromaticity combined with the non-linear space charge forces make high-brightness and high-intensity beams crossing betatron resonances along the injection flat bottom, inducing transverse emittance blow-up and beam losses. A scan of the working point plane {Qx,Qy} was done in order to identify beam destructive resonances, in the framework of a possible 2 GeV injection energy upgrade which would reduce the space charge effect on the tune. Experiments were carried out in order to review the maximum space charge tune shift for which no transverse emittance blow-up is observed. The results of measurements and simulations will be presented in this paper.

MOPS017	Simulation Studies of Macro-particles Falling into the LHC Proton Beam	proton, simulation, injection, vacuum	634
	F. Zimmermann, T. Baer, M. Giovannozzi, E.B. Holzer, E. Nebot Del Busto, A. Nordt, M. Sapinski CERN, Geneva, Switzerland N. Fuster Valencia University, Atomic Molecular and Nuclear Physics Department, Valencia, Spain Z. Yang EPFL, Lausanne, Switzerland
	We report updated simulations on the interaction of macro-particles falling from the top of the vacuum chamber into the circulating LHC proton beam. The path and charge state of micron size micro-particles are computed together with the resulting beam losses, which – if high enough - can lead to the local quench of SC magnets. The simulated time evolution of the beam loss is compared with observations in order to constrain some macro-particle parameters. We also discuss the possibility of a "multiple crossing" by the same macro-particle, the effect of a strong dipole field, and the dependence of peak loss rate and loss duration on beam current and on beam size.

MOPS071	Simulations of the Impedance of the New PS Wire Scanner Tank	simulation, impedance, extraction, vacuum	766
	B. Salvant EPFL, Lausanne, Switzerland W. Andreazza, F. Caspers, A. Grudiev, J.F. Herranz Alvarez, E. Métral, G. Rumolo CERN, Geneva, Switzerland
	The CERN PS is equipped with 4 wire scanners. It was identified that the small aperture of the current wire scanner tank causes beam losses and a new tank design was needed. The interaction of the PS bunches with the beam coupling impedance of this new tank may lead to beam degradation and wire damage. This contribution presents impedance studies of the current PS tank as well as the new design in order to assess the need to modify the design and/or install lossy materials plates dedicated to damp higher order cavity modes and reduce the total power deposited by the beam in the tank.

MOPS074	Stabilization of the LHC Single-bunch Transverse Instability at High-energy by Landau Octupoles	octupole, simulation, emittance, single-bunch	775
	E. Métral, B. Salvant CERN, Geneva, Switzerland N. Mounet EPFL, Lausanne, Switzerland
	When the first ramp was tried on Saturday 15/05/2010 with a single bunch of about nominal intensity (i.e. ~ 10¹1 p/b), the bunch became unstable in the horizontal plane at ~ 2 TeV. The three main observations were: (i) a “Christmas tree” in the transverse tune measurement application (with many synchrotron sidebands excited), (ii) beam losses (few tens of percents) in IR7, and (iii) an increase of the bunch length. This transverse coherent instability has been stabilized successfully with Landau octupoles. Comparing all the measurements performed during this first year of LHC commissioning with the theoretical and simulation predictions reveals a good agreement.

MOPZ002	MICE Beamline	dipole, emittance, solenoid, target	823
	Y. Karadzhov DPNC, Genève, Switzerland
	The muon ionization cooling experiment (MICE) is under development at the Rutherford Appleton Laboratory (UK). The goal of the experiment is to build a section of a muon cooling channel that can demonstrate the principle of Ionization cooling over a range of emittances and momenta. The MICE beam line must generate several matched muon beams with different momenta and optical parameters at the entrance of the cooling channel. This is done exploiting a titanium target dipping into the ISIS proton beam, a 5T superconducting pion decay solenoid, two dipole magnets and a mechanism for inflation of the initial emittance called diffuser. First measurements of muon rates and beam emittance performed using two TOF hodoscopes detectors will be presented.

MOPZ035	MICE Muon Beamline Particle Rate and Related Beam Loss in the ISIS Synchrotron	target, proton, synchrotron, solenoid	874
	A.J. Dobbs Imperial College of Science and Technology, Department of Physics, London, United Kingdom D. Adey University of Warwick, Coventry, United Kingdom L. Coney UCR, Riverside, California, USA
	The international Muon Ionization Cooling Experiment (MICE) will provide a proof of principle of ionization cooling, reduction of muon beam phase space, which will be needed at a future Neutrino Factory and Muon Collider. The MICE muon beam is generated by the decay of pions produced by dipping a cylindrical titanium target into the proton beam of the 800 MeV ISIS synchrotron at the Rutherford Appleton Laboratory, U.K. Studies of the particle rate in the MICE beamline and correlations with induced beam loss in ISIS are described, including the most recent data taken in the summer of 2010, representing some of the highest loss and rate conditions achieved to date. Ideally, a high rate of muons in the MICE beamline is desired, in order to facilitate the cooling measurement. However, impact on the host accelerator equipment must also be minimized. The implications of the observed beam loss and particle rate levels for MICE and ISIS are discussed.

TUOAA02	Status of UA9, the Crystal Collimation Experiment in the SPS	collimation, ion, proton, simulation	897
	W. Scandale LAL, Orsay, France
	Funding: CERN, IHEP-Protvino, Imperial-College, INFN, JINR-Dubna, LBNL, PNPI-Gartchina, SLAC UA9 was operated in the CERN-SPS for more than two years in view of investigating the feasibility of the halo collimation with bent crystals. Silicon crystals 2 mm long with bending angles of about 150 urad were used as primary collimators. The crystal collimation process was steadily achieved through channeling with high efficiency. The crystal orientation was easily set and optimized with the installed goniometer which has an angular reproducibility of about ± 10 μrad. In channeling orientation, the loss rate of the halo particles interacting with the crystal is reduced by a factor of ten, whilst the residual off-momentum halo escaping from the crystal-collimator area is reduced by a factor five. The crystal channeling efficiency of about 75 % is reasonably consistent with simulations and with single pass data collected in the North Area of the SPS. The accumulated observations, shown in this paper, support our expectation that the coherent deflection of the beam halo by a bent crystal should considerably help in enhancing the collimation efficiency in LHC.
	Slides TUOAA02 [4.297 MB]

TUPC039	Proposals for Electron Beam Transportation Channel to Provide Homogeneous Beam Density Distribution at a Target Surface	target, electron, neutron, quadrupole	1084
	A.Y. Zelinsky, I.M. Karnaukhov NSC/KIPT, Kharkov, Ukraine W.B. Liu IHEP Beijing, Beijing, People's Republic of China
	NSC KIPT neutron source will use 64x64 mm rectangular tungsten or uranium target. To generate maximum neutron flux, prevent overheating of the target and reduce thermal stress one should provide homogeneous electron beam distribution at the target surface. In the facility transportation channel three different possibilities of electron beam density redistribution along the target surface can be realized. It can be the fast beam scanning with two dimensional scanning magnets; the method of uniform beam distribution formation with linear focusing elements (dipole and quadrupole magnets) and nonlinear focusing elements (octupole magnets), when final required rectangular beam shape with homogeneous beam density is formed at target; and combined method, when one forms the small rectangular beam with homogeneous beam density distribution and scan it over the target surface with scanning magnets. In the report the all tree methods are considered and discussed considering the layout of the NSC KIPT transportation channel. Calculation results show that the proposed transportation channel lattice can provide uniform beam of rectangular shape with sizes 64x64 mm without target overheating.

TUPC070	SAFARI, an Optimized Beam Stop Device for High Intensity Beams at the SPIRAL2 Facility	linac, beam-transport, neutron, vacuum	1162
	E. Schibler IN2P3 IPNL, Villeurbanne, France L. Perrot IPN, Orsay, France
	The SPIRAL2 facility at GANIL-Caen is now in its construction phase, with a project group including the participation of many French laboratories (CNRS, CEA) and international partners. The facility will be able to produce various accelerated beams at high intensities: 40 MeV Deuterons, 33 MeV Protons with intensity until 5mA and heavy ions with A/Q=3 up to 14.5MeV/u until 1mA current. We will present the final status of the 200kW beam stop located in the high energy beam transport lines. From the beam characteristics (HEBT line up to beam stop) and activation constraints, we studied and developed a complete design of a new high efficiency Beam Stop that has been nicknamed SAFARI (Système Arrêt Faisceau Adapté Rayons Intenses - Optimized Beam Stop Device for High Intensity Beams). Special focus will be done on the adequacy between beam dynamic and thermo-mechanical behavior. The Beam Stop shape marries to the beam characteristics in order to smooth for the best power density and improve thermo-mechanical behavior under nominal and critical beams. Optimization by various fluids studies and calculations led us to a new high efficiency counter-current water cooling system.

TUPC083	Comparative Studies into 3D Beam Loss Simulations	simulation, photon, electron, positron	1198
	M. Panniello MPI-K, Heidelberg, Germany C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: Work supported by the Helmholtz Association and GSI under contract VH-NG-328. A detailed understanding and monitoring of potential beam loss mechanisms is crucial for every particle accelerator. The main motivation in low energy facilities, such as the Ultra-low energy Storage Ring (USR) at the future Facility of Low energy Antiproton and Ion Research (FLAIR), comes from the very low number of particles available which in such machine ought to be conserved. In High Energy accelerators it is the concern about activation or even physical damage of machine parts which has to be taken into serious account. The CLIC Test Facility (CTF3) at CERN provides an ideal testing ground for studies into novel BLM systems and is well suited for benchmarking the results from numerical simulations in experiments. This contribution summarizes the three-dimensional beam loss pattern as found with the commonly used codes FLUKA and Géant4. The results from these codes are compared and analyzed in detail and used for the identification of optimum beam loss monitor locations.

TUPC100	Longitudinal Beam Profile Measurement at J-PARC Separated Drift Tube Linac	cavity, linac, simulation, injection	1245
	T. Maruta KEK/JAEA, Ibaraki-Ken, Japan M. Ikegami KEK, Ibaraki, Japan A. Miura, G.H. Wei JAEA/J-PARC, Tokai-mura, Japan H. Sako JAEA, Ibaraki-ken, Japan
	We measured longitudinal beam profile at Separated Drift Tube Linac (SDTL) injection part by scanning beam transmission and beamloss at the downstream of SDTL section by changing SDTL injection phase. As the beam goes to acceptance edge, part of the beam which is out of acceptance isn't accelerate and finally it is lost by hitting to beam duct. Thus beam transmission shows sliced bunch shape by acceptance edge, it is possible to reconstruct the beam bunch shape. The result shows about 60% wider profile in both phi and E direction against to design.

TUPC102	Measurement of Beam Loss Tracks by Scintillating Fibers at J-PARC Linac	linac, background, simulation, gun	1251
	H. Sako, T. Maruta, A. Miura JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	Highest beam loss in the J-PARC linac has been observed that the ACS (Annular-Coupled Structure linac) section. Since the observed beam loss is proportional to the residual gas pressure, the source of the beam loss is considered as H0 produced in an interaction of H⁻ beams with remnant gas. If this assumption is valid, H0 hits the beam duct and changes into H⁺ and escapes from the beam duct. We constructed scintillation fiber hodoscopes to detect H⁺s and eventually identify the particle species as H⁺. The hodoscopes are made of 4 planes of hodoscopes which consists of 16 scintillation fibers of 64mm long and with 4mmx4mm cross section. We installed the hodoscopes at the upstream part of the ACS section and measured beam loss. The results are shown in this paper.

TUPC104	Beam Loss Detected by Scintillation Monitor	linac, cavity, simulation, hadron	1257
	A. Miura, K. Hasegawa, T. Maruta, N. Ouchi, H. Sako JAEA/J-PARC, Tokai-mura, Japan Z. Igarashi, M. Ikegami, T. Miyao KEK, Ibaraki, Japan
	Ar gas proportional BLMs have measured the beam loss through operations, but they are also sensitive to background noise of X-ray emitted from RF cavities. We have tried to measure the beam loss using scintillation monitors which would bring more accurate beam loss measurements with suppression of X-ray noise. We measured beam loss using scintillation beam loss monitors. Because this scintillation BLM is sensitive for low energy gamma-rays and fast neutrons, small signals from X-rays would be also detected. As the measurement results, a good signal to noise ratio is observed for the scintillation monitor with quite low sensitivity to the background X-ray. And many single events are observed in the intermediate pulse bunch with about 600 ns as pulse width. In addition, because we fabricated the filter and integrated circuit, total amount of X-ray noise can become smaller. We obtained the good performances of scintillation BLM with small effect of X-ray noise. This monitor can be used for beam loss measurement and a knob for tuning. Furthermore, because the detail structure can be detected, this monitor could be employed for another diagnostic device.

TUPC131	Overview of ESS Beam Loss Monitoring System	ion, proton, neutron, SRF	1329
	L. Tchelidze, A. Jansson ESS, Lund, Sweden
	European Spallation Source (ESS) is a multi-MW proton linear accelerator that will be built in Lund, Sweden. Due to the high power of the machine, losses need to be minimized to avoid damaging the accelerator components and quenching superconducting magnets. Loss monitors have to be positioned all across the accelerator, so that they form a reliable protection system. A careful analysis of the loss nature for ESS is in progress to determine the locations for the loss detectors. This paper presents preliminary results of the simulations for the detector response functions, which are calculated for several different energies and incident angles of protons, at certain parts of the accelerator. A simple, baseline geometry configuration is used in the calculations. This paper also gives an overview of the considered ESS beam loss monitoring system. It describes the types of the detectors which are planned to be used at ESS, and discusses the number of detectors needed along different parts of the machine. As planned, a primary tool for measuring losses at ESS will be ionization chambers, the conceptual design of which is given in this paper based on the response time considerations.

TUPC135	Beam Loss Monitors Comparison at the CERN Proton Synchrotron	injection, radiation, electron, proton	1341
	S.S. Gilardoni, S. Aumon, E. Effinger, J. Gil Flores CERN, Geneva, Switzerland U. Wienands SLAC, Menlo Park, California, USA
	CERN is planning the renovation and upgrade of the beam loss detection system for the Proton Synchrotron (PS). Improved performance in speed–to be able to monitor beam loss on a bunch-by-bunch basis–and in long-term stability–to reduce or avoid the need for periodic calibration–are aimed for. To select the most suitable technology, different detectors were benchmarked in the machine with respect to the same beam loss. The characteristics of the different detectors, the results of the measurement campaign and their suitability as future monitors for the PS are presented.

TUPC136	Analysis of Fast Losses in the LHC with the BLM System	injection, quadrupole, superconducting-magnet, proton	1344
	E. Nebot Del Busto, T. Baer, B. Dehning, E. Effinger, J. Emery, E.B. Holzer, A. Marsili, A. Nordt, M. Sapinski, R. Schmidt, B. Velghe, J. Wenninger, C. Zamantzas, F. Zimmermann CERN, Geneva, Switzerland N. Fuster Valencia University, Atomic Molecular and Nuclear Physics Department, Valencia, Spain Z. Yang EPFL, Lausanne, Switzerland
	About 3600 Ionization Chambers are located around the LHC ring to detect beam losses that could damage the equipment or quench superconducting magnets. The BLMs integrate the losses in 12 different time intervals (from 40 us to 83.8 s) allowing for different abort thresholds depending on the duration of the loss and the beam energy. The signals are also recorded in a database at 1 Hz for offline analysis. During the 2010 run, a limiting factor in the machine availability were sudden losses appearing around the ring on the ms time scale and detected exclusively by the BLM system. It is believed that such losses originate from dust particles falling into the beam, or being attracted by its strong electromagnetic field. This document describes some of the properties of these "Unidentified Falling Objects" (UFOs) putting special emphasis on their dependence on beam parameters (energy, intensity, etc). The subsequent modification of the BLM beam abort thresholds for the 2011 run that were made to avoid unnecessary beam dumps caused by these UFO losses are also discussed.

TUPC137	UFOs in the LHC	injection, kicker, simulation, acceleration	1347
	T. Baer, M.J. Barnes, B. Goddard, E.B. Holzer, J.M. Jimenez, A. Lechner, V. Mertens, E. Nebot Del Busto, A. Nordt, J.A. Uythoven, B. Velghe, J. Wenninger, F. Zimmermann CERN, Geneva, Switzerland
	One of the major known limitations for the performance of the Large Hadron Collider are so called UFOs (”Unidentified Falling Objects”). UFOs were first observed in July 2010 and have since caused numerous protection beam dumps. UFOs are thought to be micrometer sized dust particles which lead to fast beam losses with a duration of about 10 turns when they interact with the beam. In 2011, the diagnostics for such events was significantly improved which allows estimates of the properties, dynamics and production mechanisms of the dust particles. The state of knowledge and mitigation strategies are presented.

TUPC139	Overview of the CLIC Beam Instrumentation	linac, cavity, laser, instrumentation	1350
	T. Lefèvre CERN, Geneva, Switzerland
	Driven by beam dynamic considerations the Compact Linear Collider (CLIC) is expected to require extremely tight tolerances on most beam parameters. An important milestone was reached in 2011 with the completion of the CLIC conceptual design report. In this context the requirements for CLIC beam instrumentation has been reviewed and studied in detail for the whole accelerator complex with the aim of demonstrating feasibility. A preliminary choice has been made for every CLIC instrument, serving as a baseline scenario for the next phase of the project which will concentrate on the detailed design, engineering and test of CLIC devices. Whenever possible existing solutions have been studied, focusing on any improvements necessary to meet the CLIC performance criteria. When no such devices exists, or if cost considerations come into play, new technologies have been under study. Several prototypes are already well advanced and are currently under test. This paper presents an overview of CLIC beam instrumentation, the possible reach of their performance and an outlook on future developments.

TUPC141	LHC Beam Loss Pattern Recognition	monitoring, proton, resonance, collider	1353
	A. Marsili, E.B. Holzer, P.M. Puzo CERN, Geneva, Switzerland
	One of the systems protecting CERN's Large Hadron Collider (LHC) is the Beam Loss Monitoring system (BLM). More than 3600 monitors are installed around the ring. The beam losses are permanently integrated over 12 different time intervals (from 40 microseconds to 84 seconds). When any loss exceeds the thresholds defined for the integration window, the beam is removed from the machine. Understanding the origin of a beam loss is crucial for machine operation, as it can help to avoid a repeat of the same scenario. The signals read from given monitors can be considered as entries of a vector. This article presents how a loss map of unknown cause can be decomposed using vector based analysis derived from well-known loss scenarios. The algorithms achieving this decomposition are described, as well as the accuracy of the results.

TUPC142	The Particle Identification System for the MICE Beamline Characterization	emittance, electron, laser, solenoid	1356
	M. Bonesini INFN MIB, MILANO, Italy Y. Karadzhov DPNC, Genève, Switzerland
	The International Muon Ionization Cooling Experiment (MICE) will carry out a systematic investigation of a ionization cooling section of a muon beam, for the future Neutrino Factory and the future Muon Collider. As the emittance measurement will be done on a particle-by-particle basis, a sophisticated beam instrumentation is needed to measure both particle coordinates and timing vs RF in a harsh environment due to high particle rates, fringe magnetic fields and RF backgrounds. A PID system, based on three time-of-flight stations (with resolutions up to 50-60 ps), two Aerogel Cerenkov counters and a KLOE-like calorimeter (KL) has been constructed and has allowed the commissioning of the MICE muon beamline in 2010. It will be complemented in 2011 by an Electron Muon Ranger to determine the muon range at the downstream end of the cooling section. Detector performances, as obtained in the 2010 run, will be shown and the use of PD detectors for the beamline characterization, including a preliminary measure of emittance, fully illustrated.

TUPC147	A Micro-Channel Plate Based Gas Ionization Profile Monitor with Shaping Field Electrodes for the ISIS H⁻ Injector	ion, controls, vacuum, radiation	1371
	P.G. Barnes, G.M. Cross, B.S. Drumm, S.A. Fisher, S.J. Payne, A. Pertica, C.C. Wilcox STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	Beam profile measurements within the ISIS H⁻ injector line are achieved using destructive devices such as moving wire scanners. To avoid damage to the wires, measurements are made with the injector operating on reduced power. This paper reports the development of a Micro-Channel Plate based profile monitor which allows beam measurements to be made under normal operating conditions. The monitor produces profiles by measuring the +ion current resulting from the interaction of the H⁻ beam with the surrounding residual gas. The 32 channel Micro-Channel Plate is mounted on a rotating arm to enable it to be positioned parallel to the beam for calibration (all channels then measure the same +ion current) and perpendicular to the beam for profile measurements. A 15kV drift field is used together with field shaping electrodes to ensure a flat electric field gradient across the monitor, thereby minimising distortion of the profile due to the electric field. This paper details all aspects of the design and construction of this profile monitor. Beam profiles are compared to previous wire scanner results. Shaping field upgrades are discussed to improve the longitudinal field shape.

TUPC151	Cherenkov Fibre Optic Beam Loss Monitor at ALICE	photon, laser, electron, monitoring	1383
	A. Intermite The University of Liverpool, Liverpool, United Kingdom A. Intermite, M. Putignano, A. Wolski Cockcroft Institute, Warrington, Cheshire, United Kingdom
	The need for real-time monitoring of beam losses, including evaluation of their intensity and the localization of their exact position, together with the possibility to overcome the limitations due to the reduced space for the diagnostics, makes optical fibres (using the Cherenkov Effect) one of the most suitable and explored candidate for beam loss monitoring. In this contribution, we report on an optical fibre beam loss monitor based on large numerical aperture pure silicon fibres and silicon photomultipliers, tested at ALICE, Daresbury Laboratories, UK. The original design of the sensor has the advantage to combine the functions of a real time detector and a transmission line. It also allows reading the signals independently and determining the time and position of the losses without the use of an external trigger.

TUPC152	Comparative Study of Performance of Silicon Photomultipliers for Use in Cherenkov Fibre Optic Beam Loss Monitors	photon, electron, monitoring, lattice	1386
	A. Intermite The University of Liverpool, Liverpool, United Kingdom A. Intermite, M. Putignano, A. Wolski Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Silicon Photomultipliers (SiPMs) are semiconductor photo-sensitive devices built from a matrix of Single Photon Avalanche Diodes (SPADs) on a common silicon substrate, working in the limited Geiger mode and with a common readout. The fast counting ability, high timing resolution, immunity to magnetic field up to 15 T, low power consumption and relative small temperature dependence together with the small dimensions make SiPMs excellent candidates as commercially available solid state detectors, and a promising alternative to traditional photomultiplier tubes for single photon detection. Nevertheless, SiPMs do suffer from erroneous counting due to noise effects that can deteriorate their performances. These effects are, in general, heavily dependent on manufacturing quality. In this contribution, results are reported of the characterization of different models of SiPMs in terms of noise spectra and response to light, and a procedure for determining quality manufacturing parameters is described.

TUPC153	Study of the Response of Silicon Photomultipliers in Presence of Strong Cross-talk Noise	photon, radiation, positron, heavy-ion	1389
	M. Putignano, A. Intermite The University of Liverpool, Liverpool, United Kingdom M. Putignano, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: Work supported by STFC, the EU under GA-ITN-215080, the Helmholtz Association and GSI under VH-NG-328. Silicon Photomultipliers (SiPM) are interesting detectors for beam diagnostics applications where they could replace photomultiplier tubes as large dynamic range photon counting devices due to their reduced dimensions and costs, higher photon detection efficiency, immunity to magnetic fields and low operation voltage. Possible applications include longitudinal beam profile measurements by synchrotron light imaging, detection of optical transition radiation for energy spectrum measurements and medical imaging. However, quantitative measurement with SiPMs are jeopardized by the systematic reading error due to Optical Cross-talk (OC), i.e. optical coupling between neighboring diodes in the array. OC results in overestimation of the impinging light level, and reflects the probability of a triggered avalanche creating a photon of suitable energy and direction to fire a second avalanche in another diode. In this paper, we derive a generalized response distribution for SiPM in presence of cross-talk noise, which overcomes the limitations of assumptions currently made in literature and provides a correction of the SiPM response distribution valid for arbitrary large levels of cross-talk.

TUPS007	Construction and Test of a Cryocatcher Prototype for SIS100*	ion, vacuum, heavy-ion, controls	1527
	L.H.J. Bozyk, D.H.H. Hoffmann TU Darmstadt, Darmstadt, Germany H. Kollmus, P.J. Spiller, M. Wengenroth GSI, Darmstadt, Germany
	Funding: EU-FP-7 project COLMAT, FIAS The main accelerator, SIS100, of the FAIR-facility will provide heavy ion beams of highest intensities. Ionization beam loss is the most important loss mechanism at operation with high intensity, intermediate charge state heavy ions. A special synchrotron design has been developed for SIS100, aiming for hundred percent control of ionization beam loss by means of a dedicated cold ion catcher system. To suppress dynamic vacuum effects, the cryo catcher system shall also provide a significantly reduced effective desorption yield. The construction and tests of a prototype cryo ion catcher is a workpackage of the EU-FP-7 project COLMAT. A prototype test setup including cryostat has been constructed, manufactured and tested at GSI under realistic conditions with heavy ion beams of the of the heavy ion synchrotron SIS18. The design and results are presented.

TUPS013	Development of the H0 Dump Branch Duct for the Additional Collimation System in J-PARC RCS	septum, shielding, collimation, vacuum	1545
	M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	For the new collimation system in the J-PARC RCS, we have the H0 branch duct installed at the dump septum magnet remodeled. This new branch duct is made of the two kinds of the stainless steels as follows; austenitic stainless steel, SUS316L and ferritic stainless steel, SUS430. In order to research on the property of the SUS430, test ducts were made in various heat-treating condition. In this presentation, we report the design of the new H0 branch duct and the study results with the test ducts.

TUPS037	Preliminary Assessment of Beam Impact Consequences on LHC Collimators	simulation, proton, collimation, controls	1617
	M. Cauchi, R.W. Assmann, A. Bertarelli, R. Bruce, F. Carra, A. Dallocchio, D. Deboy, N. Mariani, A. Rossi, N.J. Sammut CERN, Geneva, Switzerland M. Cauchi, P. Mollicone UoM, Msida, Malta L. Lari IFIC, Valencia, Spain
	The correct functioning of the LHC collimation system is crucial to attain the desired LHC luminosity performance. However, the requirements to handle high intensity beams can be demanding. In this respect, the robustness of the collimators plays an important role. An accident which causes the proton beam to hit a collimator might result in severe beam-induced damage and, in some cases, replacement of the collimator, with consequent downtime for the machine. In this paper, several case studies representing different realistic beam impact scenarios are shown. A preliminary analysis of the thermal response of tertiary collimators to beam impact is presented, from which the most critical cases can be identified. Such work will also help to give an initial insight on the operational constraints of the LHC by taking into account all relevant collimator damage limits.

TUPS040	Driving the LHC Collimators' Stepping Motors over 1 km with High Accuracy avoiding EMI Effects	controls, feedback, impedance, radiation	1626
	A. Masi, G. Conte, R. Losito, M. Martino CERN, Geneva, Switzerland
	The LHC collimators are exposed to very high levels of radiation, which means that the power drivers must be installed far from the stepping motors that they drive. Due to the geometry of the underground installations, the distances can be up to 1 km. The long cables that connect the drivers to the motors behave as transmission lines modifying dramatically the impedance seen by the drivers and consequently jeopardizing the control performance of Pulse Width Modulation (PWM) drivers. In this paper we address this problem, provide an analytical model of the driver-cable-motor system and describe the analog solution we have developed to improve the performance of a typical off the shelf driver. Finally we characterize the improvement of the performances with measurements of positioning repeatability and show that electromagnetic emissions from the long cables are drastically reduced, making the use of stepping motors compatible with extremely sensitive instrumentation such as the LHC Beam Loss Monitors (BLM).

TUPS050	Target Optimisation Studies for MuSR Applications	target, proton, simulation, neutron	1641
	A. Bungau, C. Bungau, R. Cywinski University of Huddersfield, Huddersfield, United Kingdom P.J.C. King, J.S. Lord STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
	Considering the ISIS muon target as a reference, Geant4 simulations have been performed to optimise the target parameters with respect to muon and pion yield. Previous studies suggested that the muon production can be optimised by using a thin graphite slab target with an incident proton energy significantly lower than initially considered. The current paper discusses a possible target design fully optimised for MuSR studies.

TUPS084	Development Status of PPS, MPS and TS for IFMIF/EVEDA Prototype Accelerator	controls, radiation, status, monitoring	1734
	H. Takahashi, T. Kojima, T. Narita, K. Nishiyama, H. Sakaki, K. Tsutsumi JAEA, Aomori, Japan
	Control System for IFMIF/EVEDA* prototype accelerator consists of six subsystems; Central Control System (CCS), Local Area Network (LAN), Personnel Protection System (PPS), Machine Protection System (MPS), Timing System (TS) and Local Control System (LCS). The IFMIF/EVEDA prototype accelerator provides deuteron beam with the power more than 1 MW, which is as same as that in cases of J-PARC and SNS. Then, the PPS is required to protect technical and engineering staff against unnecessary exposure and the other danger phenomena. The MPS and the TS are strongly required a high performance and precision to avoid radio-activation of the accelerator components. To realize these requirements, the PPS designed that Programmable Logic Controllers (PLCs) are used mainly, and a sequence is programmed for entering and leaving of controlled area and etc. Hardware and logic sequences for the MPS are designed to realize the beam inhibition time within 30 micro-seconds. The TS prototype modules were designed and tested using 10 MHz master clock and 100 Hz reference trigger. This article presents the PPS, MPS and TS design in details. * International Fusion Material Irradiation Facility / Engineering Validation and Engineering Design Activity

TUPZ006	Aperture Determination in the LHC Based on an Emittance Blowup Technique with Collimator Position Scan	emittance, injection, optics, storage-ring	1810
	R.W. Assmann, R. Bruce, M. Giovannozzi, G.J. Müller, S. Redaelli, F. Schmidt, R. Tomás, J. Wenninger, D. Wollmann CERN, Geneva, Switzerland M. Alabau IFIC, Valencia, Spain
	A new method to determine the LHC aperture was proposed. The new component is a collimator scan technique that refers the globally measured aperture limit to the shadow of the primary collimator, expressed in σs of rms beam size. As a by-product the BLM response to beam loss is quantified. The method is described and LHC measurement results are presented.

TUPZ012	Machine-induced Showers entering the ATLAS and CMS Detectors in the LHC	simulation, proton, background, collimation	1825
	R. Bruce, R.W. Assmann, V. Boccone, H. Burkhardt, F. Cerutti, A. Ferrari, M. Huhtinen, W. Kozanecki, Y.I. Levinsen, A. Mereghetti, A. Rossi, Th. Weiler CERN, Geneva, Switzerland N.V. Mokhov Fermilab, Batavia, USA
	One source of experimental background in the LHC is showers induced by particles hitting the upstream collimators or particles that have been scattered on the residual gas. We estimate the flux and distribution of particles entering the ATLAS and CMS detectors through FLUKA simulations originating from tertiary collimator hits and inelastic beam-gas interactions. Comparisons to MARS results are also presented.

TUPZ015	Electron Cloud Parameterization Studies in the LHC	electron, vacuum, simulation, emittance	1834
	C.O. Domínguez, G. Arduini, V. Baglin, G. Bregliozzi, J.M. Jimenez, E. Métral, G. Rumolo, D. Schulte, F. Zimmermann CERN, Geneva, Switzerland
	During LHC beam commissioning with 150, 75 and 50-ns bunch spacing, important electron-cloud effects, like pressure rise, cryogenic heat load, beam instabilities or emittance growth, were observed. The main strategy to combat the LHC electron cloud relies on the surface conditioning arising from the chamber-surface bombardment with cloud electrons. In a standard model, the conditioning state of the beam-pipe surface is characterized by three parameters: 1. the secondary emission yield; 2. the incident electron energy at which the yield is maximum; and 3. the probability of elastic reflection of low-energy primary electrons hitting the chamber wall. Since at the LHC no in-situ secondary-yield measurements are available, we compare the relative local pressure-rise measurements taken for different beam configurations against simulations in which surface parameters are scanned. This benchmark of measurements and these simulations is used to infer the secondary-emission properties of the beam-pipe at different locations around the ring and at various stages of the surface conditioning. In this paper we present the methodology and first results from applying the technique to the LHC.

TUPZ025	Experience with Offset Collisions in the LHC	luminosity, target, emittance, controls	1858
	G. Papotti, R. Alemany-Fernandez, F. Follin, R. Giachino, W. Herr, T. Pieloni, M. Schaumann CERN, Geneva, Switzerland R. Calaga, R. Miyamoto BNL, Upton, Long Island, New York, USA
	To keep the luminosity under control, some experiments require the adjustment of the luminosity during a fill, so-called luminosity leveling. One option is the separate the beams transversely and adjust the separation to the desired collision rate. The results from controlled experiments are reported and interpreted. The feasibility of this method for ultimate luminosities is discussed.

TUPZ028	Beam Based Optimization of the Squeeze at the LHC	feedback, optics, simulation, controls	1867
	X. Buffat EPFL, Lausanne, Switzerland M. Lamont, S. Redaelli, J. Wenninger CERN, Geneva, Switzerland
	The betatron squeeze is a critical operational phase for the LHC because it is carried out at top energy, with the maximum stored energy and with reduced aperture margins in the superconducting triplets. A stable operation with minimum beam losses must be achieved in order to ensure a safe and efficient operation. The operational experience at the LHC showed that this is possible. The operation in 2010 is reviewed. In particular, orbit, tune and chromaticity measurements are investigated and correlated to beam losses. Different optimizations are then proposed towards a more efficient and robust operation. The improvements obtained for the operation in 2011 are presented.

TUPZ037	Momentum Aperture for the Low Beta* Lattices in RHIC Au-Au Runs	lattice, dynamic-aperture, heavy-ion, ion	1891
	Y. Luo, K.A. Brown, W. Fischer, X. Gu, G. Robert-Demolaize, T. Roser, V. Schoefer, S. Tepikian, D. Trbojevic BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In this article we calculate the momentum apertures with the low beta* lattices of 100 GeV RHIC Au-Au run. With RF re-bucketing, the maximum off-momentum spread reaches 1.7 ·10^-03 at store. To improve the momentum aperture, we need to reduce the nonlinear chromaticities. The methods to correct second order chromaticities in RHIC rings are presented. We also scan beta* at IP6 and IP8 and working point. The challenges to further reduce beta* in the RHIC Au-Au operation are discussed.

WEPC015	Tuning Methods for HIMAC Multiple-energy Operation	betatron, acceleration, resonance, synchrotron	2037
	K. Katagiri, T. Furukawa, Y. Iwata, K. Noda, S. Sato, T. Shirai NIRS, Chiba-shi, Japan K. Mizushima Chiba University, Graduate School of Science and Technology, Chiba, Japan E. Takeshita Gunma University, Heavy-Ion Medical Research Center, Maebashi-Gunma, Japan
	Beam stability of multiple-energy operation at HIMAC synchrotron was improved for the fast raster-scanning irradiation. In order to improve the transverse stability, the working point of the betatron tune was investigated during one operation cycle. The signals were collected from the beam position monitor using a fast data-acquisition unit. The temporal evolution of the horizontal and vertical betatron tune was evaluated by using the short time Fourier transform. Analyzed results showed that variation of the betatron tune in the acceleration interval passed through the 3rd-order coupling resonance line, and it caused undesirable emittance growth. In order to keep the working point within the desirable operating region, the current pattern of the power supplies for the quadrupole magnets was corrected by using the variation of the betatron tune. The experimental results showed that the working point could be successfully stabilized, and the undesirable beam losses could be reduced during the acceleration interval.

WEPC021	Optical Design of the Proton Beam Lines for the Neutron Research Complex INR RAS and Medical Application	proton, neutron, target, linac	2049
	M.I. Grachev, E.V. Ponomareva RAS/INR, Moscow, Russia
	The optical design for the layout of the beam lines for the neutron research complex INR RAS and medical application on the basis of the Linear accelerator are presented here. The proposed schemes have been realized at the INR RAS. The necessary size and shape of the proton beam at the location of the neutron target are obtained. Methods and results for the tuning of the high current beams are presented in this paper.

WEPC054	Amplitude Dependent Tune Spread in the CR Operated as an Antiproton Collector	sextupole, quadrupole, antiproton, simulation	2136
	A. Dolinskii, C. Dimopoulou, O.E. Gorda, S.A. Litvinov, F. Nolden, M. Steck GSI, Darmstadt, Germany
	The Collector Ring is planned to be built for efficient cooling of antiprotons and rare isotopes beams. In order to accept hot antiproton beams coming from a separator large aperture magnets are required. This paper examines the effects which, may influence on the beam dynamic because of both large both betatron amplitude oscillations (240 mm mrad) and momentum spread (6%). Using analytic expressions the amplitude-dependent tune shifts driven by sextupole magnets, fringe field of quadrupole magnets and kinematics effects have been calculated. The results are compared with numerical simulations. Tracking studies for the CR operated as an antiproton collector have been performed considering the real shape of the magnetic field of the wide aperture quadrupole. We report on quantitative studies of the effects on the tune spread and its influence on the beam losses.

WEPC057	Estimation of the Dynamic Aperture by Transverse Beam Excitation with Noise Close to a Resonance	dynamic-aperture, lattice, resonance, sextupole	2145
	S. Sorge, G. Franchetti GSI, Darmstadt, Germany
	The present heavy ion synchrotron SIS-18 will be upgraded to be used as a booster for further synchrotrons being part of the FAIR project underway at GSI. Recently, a method was developed to measure the physical aperture of SIS-18 using transverse RF noise. This method is based on the transverse expansion of the beam with noise beyond the limiting aperture generating beam loss. The aperture was determined from the comparison of the resulting time evolution of the beam current in the machine with that obtained from a numerical simulation. In this study we attempt to apply this method to determine the dynamic aperture of SIS-18.

WEPC164	First Operation of a Fiber Beam Loss Monitor at the SACLA FEL	undulator, vacuum, electron, radiation	2367
	X.-M. Maréchal, T. Itoga JASRI/SPring-8, Sayo-gun, Japan Y. Asano RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	A fiber-based Cerenkov beam loss monitor (CBLM) has been developed as a quick and long-range detection tool for radiation safety at the X-ray FEL SACLA (SPring-8 angstrom compact free electron laser) to minimize electron beam losses. Based on tests carried out at the 250 MeV SPring-8 Compact SASE Source facility, large core (400 μm), long (>120 m) multimode fibers were selected and installed in the undulator section of SACLA. We report on the first few months of operation of the CBLM. During the commissioning of the X-FEL, the CBLM has performed effectively, with a detection limit below 10 pC per pulse across the 110 meters of the in-vacuum undulators, and with a position accuracy of less than 2 m. Experimental results are presented along with detailed numerical studies including the geometry of in-vacuum insertion devices, and discussed.

WEPC165	Monte Carlo Simulation of the Total Dose Distribution around the 12 MeV UPC Race-track Microtron and Radiation Shielding Calculations	shielding, radiation, simulation, target	2370
	C. de la Fuente, M.A. Duch, Yu.A. Kubyshin UPC, Barcelona, Spain V.I. Shvedunov MSU, Moscow, Russia
	The Technical University of Catalonia is building a miniature 12 MeV electron race-track microtron for medical applications. In the paper we study the leakage radiation caused by beam losses inside the accelerator head, as well as the bremstrahlung radiation produced by the primary beam in the commissioning setting. Results of Monte Carlo simulations using the PENELOPE code are presented and two shielding schemes, global and local, are studied. The obtained shielding parameters are compared with estimates based on international recommendations of the radiation safety standards.

WEPC166	Licensing and Safety Issues of the ESS Accelerator	shielding, radiation, target, neutron	2373
	P.E.T. Jacobsson, M. Brandin, D. Ene, T. Hansson ESS, Lund, Sweden
	The licensing process for the European Spallation Source (ESS) has started up. The process includes both an application to the Environmental Court in Sweden as well as the application towards the Swedish Radiation Protection Authority (SSM). The applications will be based on an Environmental Impact Assessment EIA) and a Safety Analysis Report (SAR). One important step has been to define which regulations that apply for ESS. ESS has also set up General Safety Objectives (GSO). Based on the GSO and the legal requirements, the process design of the whole ESS facility is ongoing. This paper will focus upon the radiation safety issues related to the accelerator. This includes items as radiation shielding, personal protection system and operation emissions. Analyses and calculations, based on a preliminary design and layout of the ESS accelerator, will be presented. Discussion is made on issues like shielding material, shielding design and analysis models.

WEPC170	Handling of BLM Abort Thresholds in the LHC	monitoring, injection, quadrupole, proton	2382
	E. Nebot Del Busto, B. Dehning, E.B. Holzer, S. Jackson, G. Kruk, M. Nemcic, A. Nordt, A. Orecka, C. Roderick, M. Sapinski, A. Skaugen, C. Zamantzas CERN, Geneva, Switzerland
	The Beam Loss Monitoring system (BLM) for the LHC consists of about 3600 Ionization Chambers located around the ring. Its main purpose is to request a beam abort when the measured losses exceed a certain threshold. The BLM detectors integrate the measured signals in 12 different time intervals (running from 40 us to 83.8 s) enabling for a different set of abort thresholds depending on the duration of the beam loss. Furthermore, 32 energy levels running from 0 to 7 TeV account for the fact that the energy density of a particle shower increases with the energy of the primary particle, i.e. the beam energy. Thus, about 1.3·10⁶ thresholds must be handled and send to the appropriate processing modules for the system to function. These thresholds are highly critical for the safety of the machine and depend to a large part on human judgment, which cannot be replaced by automatic test procedures. The BLM team has defined well established procedures to compute, set and check new BLM thresholds, in order to avoid and/or find non-conformities due to manipulation. These procedures, as well as the tools developed to automate this process are described in detail in this document.

WEPC171	Requirements of a Beam Loss Monitoring System for the CLIC Two Beam Modules	photon, linac, simulation, monitoring	2385
	S. Mallows The University of Liverpool, Liverpool, United Kingdom E.B. Holzer, A.P. Mechev, J.W. van Hoorne CERN, Geneva, Switzerland C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	he Compact Linear Collider (CLIC) study investigates the feasibility of a high-energy electron-positron linear collider optimized for a centre of mass energy of 3 TeV. To achieve the high accelerating gradients, the RF power is produced by a novel two-beam acceleration method in which a decelerating drive beam supplies energy to the main accelerating beam. The linacs are arranged in modular structures referred to as the two beam modules which cover 42 km of beamline. Beam losses from either beam can have severe consequences due to the high intensity drive beam and the high energy, small emittance main beam. This paper presents recent developments towards the design of a Cherenkov fiber BLM system and discusses its ability to distinguish losses originating from either beam.

WEPC172	Beam-induced Quench Test of a LHC Main Quadrupole	simulation, proton, quadrupole, monitoring	2388
	A. Priebe, K. Dahlerup-Petersen, B. Dehning, E. Effinger, J. Emery, E.B. Holzer, C. Kurfuerst, E. Nebot Del Busto, A. Nordt, M. Sapinski, J. Steckert, A.P. Verweij, C. Zamantzas CERN, Geneva, Switzerland A. Priebe EPFL, Lausanne, Switzerland
	Unexpected beam loss might lead to transition of a superconducting accelerator magnet to a normal conducting state. The LHC beam loss monitoring (BLM) system is designed to abort the beam before the energy deposited in the magnet coils reaches a quench-provoking level. In order to verify the threshold settings generated by simulation, a series of beam-induced quench tests at various beam energies have been performed. The beam losses are generated by means of an orbit bump peaked in one of the main quadrupole magnets. The analysis not only includes BLM data but also data from the electrical quench protection and cryogenic systems. The measurements are compared to Geant4 simulations of energy deposition inside the coils and corresponding BLM signal outside the cryostat. The results are also extrapolated to higher beam energies.

WEPC173	LHC Magnet Quench Test with Beam Loss Generated by Wire Scan	proton, simulation, electron, quadrupole	2391
	M. Sapinski, F. Cerutti, K. Dahlerup-Petersen, B. Dehning, J. Emery, A. Ferrari, A. Guerrero, E.B. Holzer, M. Koujili, A. Lechner, E. Nebot Del Busto, M. Scheubel, J. Steckert, A.P. Verweij, J. Wenninger CERN, Geneva, Switzerland
	Beam losses with millisecond duration have been observed in the LHC in 2010 and 2011. They are expected to be provoked by dust particles falling into the beam. These losses could compromise the LHC availability if they provoke quenches of superconducting magnets. In order to investigate the quench limits for this loss mechanism, a quench test using the wire scanner has been performed, with the wire movement through the beam mimicking a loss with similar spatial and temporal distribution as in the case of dust particles. This paper will show the conclusions reached for millisecond-duration dust-provoked quench limits. It will include details on the maximum energy deposited in the coil as estimated using FLUKA code, showing good agreement with quench limit estimated from the heat transfer code QP3. In addition, information on the damage limit for carbon wires in proton beams will be presented, following electron microscope analysis which revealed strong wire sublimation.

WEPC174	A Failure Catalogue for the LHC	monitoring, extraction, vacuum, injection	2394
	S. Wagner, R. Schmidt, B. Todd, J.A. Uythoven, M. Zerlauth CERN, Geneva, Switzerland
	The LHC, with a stored energy of more than 360 MJ per beam, requires a complex machine protection system to prevent equipment damage. The system was designed based on a large number of possible failures in the subsystems and operational phases of the LHC. This led to a mixed system with active and passive protection. The active part monitors many thousand parameters (such as beam losses, temperatures in superconducting magnets, power converter currents, etc.) and triggers a beam dump in case a failure is detected. The passive part includes protection elements like collimators and beam absorbers to ensure the prevention of damage in case of single turn beam losses (e.g. during beam transfer and injection). So far, the knowledge of the possible failures is distributed over the different teams involved in the design, construction and operation of the LHC. A newly started project aims at bringing together this knowledge in a common failure catalogue. The chosen approach in addition is expected to allow for the identification of failures that might not have been considered yet or that require further measures. This paper introduces the approach and presents the first experience.

WEPC176	Beam Loss Monitoring and Machine Protection System Design and Application for the ALICE Test Accelerator at Daresbury Laboratory	monitoring, radiation, dipole, simulation	2400
	S.R. Buckley, J.-L. Fernández-Hernando STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	ALICE is a demonstrator accelerator system which has been designed and built at Daresbury Laboratory. The heart of this facility is an ERL accelerator and a powerful multi-terrawatt laser. It serves as an advanced test facility for novel accelerator and photon science applications. Beam loss monitoring and machine protection systems are vital areas for the successful operation of ALICE. These systems are required, both for efficient machine set up and for hardware protection during operation. This paper gives an overview of the system design, commissioning details and a summary of the systems’ effectiveness as a diagnostic tool.

WEPO006	Suppression of Leakage Fields from DC Magnets in J-PARC 3 GeV RCS	shielding, extraction, septum, vacuum	2412
	M. Yoshimoto, H. Harada, N. Hayashi, H. Hotchi, M. Kinsho, P.K. Saha, K. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	In the J-PARC 3 GeV RCS, we found that DC leakage fields from the extraction beam line significantly affected the beam. For this issue, we installed additional shields and got the 40% reduction of the DC leakage field. Thus the circulating beam loss was successfully reduced. In this presentation, we report the detail of the shield structure and the results of the beam studies.

WEPS003	SIS18 – Intensity Record with Intermediate Charge State Heavy Ions	ion, heavy-ion, injection, acceleration	2484
	P.J. Spiller GSI, Darmstadt, Germany L.H.J. Bozyk FIAS, Frankfurt am Main, Germany P. Puppel HIC for FAIR, Frankfurt am Main, Germany
	Funding: Project partly funded by the European Community DIRAC-PHASE-1 / Contract number: 515876 In order to reach the desired intensities of heavy ion beams for the experiments at FAIR, SIS18 and SIS100 have to be operated with intermediate charge states. Operation with intermediate charge state heavy ions at the intensity level of about 10¹¹ ions per cycle has never been demonstrated elsewhere and requires a dedicated upgrade program for SIS18 and a dedicated machine design for SIS100. The specific problems coming along with the intermediate charge state operation in terms of charge exchange processes at collisions with residual gas atoms, pressure bumps by ion induced desorption and corresponding beam loss appears far below the typical space charge limits. Thus, new design concepts and new technical equipment addressing these issues are developed and realized with highest priority. The upgrade program of SIS18 addressing the goal of minimum ionization beam loss and stable residual gas pressure conditions has been defined in 2005. A major part of this upgrade program has been successfully realized, with the result of a world record in accelerated number of intermediate charge state heavy ions.

WEPS008	Operation Status and Future Plan of J-PARC Main Ring	extraction, kicker, linac, betatron	2499
	T. Koseki KEK, Ibaraki, Japan
	The J-PARC Main Ring (MR) has started users operation since 2009. The MR has two beam extraction systems. One is a fast extraction (FX) system for beam delivery to the neutrino beam line of the Tokai-to-Kamioka (T2K) experiment, and the other is a slow extraction (SX) system for beam delivery to the hadron experimental hall. For the T2K experiment, the maximum beam power of 145 kW is delivered continuously. For users of the hadron experimental hall, the beam power of 3 kW is delivered with extraction efficiency of 99.5%. In this paper, status of the high power beam operation of the MR is presented. Future prospect for increasing beam intensity is also discussed.

WEPS046	Longitudinal Beam Acceptance of J-PARC Drift Tube Linac	DTL, linac, simulation, cavity	2592
	T. Maruta KEK/JAEA, Ibaraki-Ken, Japan M. Ikegami KEK, Ibaraki, Japan A. Miura, G.H. Wei JAEA/J-PARC, Tokai-mura, Japan H. Sako JAEA, Ibaraki-ken, Japan
	The longitudinal acceptance of the J-PARC Drift Tube Linac (DTL) was measured by synchronous phase scan method. The IMPACT simulation indicated DTL longitudinal acceptance is shrinked if the DTL tank level reduced, but beam energy finally acheved at the Linac is almost same as the case of nominal tank level. We measured the acceptance and confirmed the simulation is correct.

WEPS047	Beamloss Study at J-PARC Linac by using Geant4 Simulation	simulation, scattering, linac, radiation	2595
	T. Maruta JAEA/J-PARC, Tokai-mura, Japan
	Beamloss is one of the key issue for intense hadron beam accelerators. Most of case, origin of beamloss is scattering process between beam particle and residual gas inside vacuum duct. In the case of J-PARC Linac, H⁻ ions emitted from an Ion source are accelerated up to 181 MeV, then the beam is transported to RCS. The H⁻ ion is the system comprised from a proton and two electrons. If the H⁻ ion is scattered with residual gas, these one or two electrons are escaped, then H⁻ becomes H0 or H⁺(proton). H0 or H⁺ is uncontrollable and finally it goes to beam duct. This process is based on physics process, and Geant4 is matched to this kind of simulation study. I programmed SDTL (50 MeV) to L3BT (181 MeV) section at J-PARC Linac by using Geant4 code. I also wrote H⁻ and H0 library which makes it possible for Geant4 to simulate them. I will show the simulation results.

WEPS048	Dependence of Beam Loss on Vacuum Pressure Level in J-PARC Linac	vacuum, linac, ion, collimation	2598
	G.H. Wei KEK/JAEA, Ibaraki-Ken, Japan K. Hirano, T. Maruta, A. Miura JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan K. Ikegami J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	In J-PARC linac, a 181-MeV negative hydrogen beam is supported to a succeeding 3-GeV synchrotron with normal operation power at 100-300 kW. During operation, a beam loss in the straight section of the beam transport line immediately after the linac exit is found. The residual radiation level reaches 0.3 mSv/h on the surface of the vacuum chamber several hours after the beam shutdown with the linac beam power of 12 kW. We suppose that the residual gas scattering of negative hydrogen ions generates neutral hydrogen atoms and they give rise to the beam loss by hitting the vacuum chamber wall. To confirm this speculation, the vacuum pressure level in the linac had been changed in order to find the dependence of the beam loss on it. After data analysis, we found the relationship between beam loss amplitude, which was attained from beam loss signal, and vacuum pressure was linear. Corresponding deduction and simulation has been down according to the residual gas components in linac chamber. In this paper, we present the experimental result and some simulations in this study.

WEPS071	High Power, High Energy Cyclotrons for Muon Antineutrino Production: the DAEdALUS Project	proton, cyclotron, target, extraction	2667
	J.R. Alonso, T. Smidt MIT, Cambridge, Massachusetts, USA
	Neutrino physics is very much at the forefront of today's research. Large detectors installed in deep underground locations study neutrino masses, CP violation, and oscillations using neutrino-sources including long- and short-baseline beams of neutrinos from muons decaying in flight. DAEdALUS* looks at neutrinos from stopped muons, “Decay At Rest (DAR)” neutrinos. The DAR neutrino spectrum has no electron antineutrinos (nu-e-bar) (pi-minus are absorbed), so a detector with much hydrogen (water-Cherenkov or liquid scintillator) is sensitive to appearance of nu-e-bar’s oscillating from nu-mu-bar via inverse-beta-decay. Oscillations are studied using shorter baselines, less than 20 km reaching the same range as the current and planned high-energy neutrino lines at Fermilab. As the neutrino flux is not variable, nor is the energy, the baseline is varied, plans call for 3 accelerator-based neutrino sources at 1.5, 8 and 20 km with staggered beam-on cycles. Key is cost-effectively generating megawatt beams of 800 MeV protons. A superconducting ring cyclotron is being designed by L. Calabretta and his group*. This revolutionary design could find application in many ADS-related fields. DAEdALUS Expression of Interest, arXiv:10⁰⁶.0260 ** Calabretta et al., "A Superconducting Ring Cyclotron to Search for CP Violation in the Neutrino Sector", this conference

WEPS094	Dynamic Vacuum Stability in SIS100	ion, vacuum, extraction, cryogenics	2724
	P. Puppel, U. Ratzinger IAP, Frankfurt am Main, Germany P.J. Spiller GSI, Darmstadt, Germany
	SIS100 is the main synchrotron of the FAIR project. It is designed to accelerate high intensity intermediate charge state uranium beams from 200 MeV/u up to 2.7 GeV/u. Intermediate charge state heavy ions are exposed to a high probability of charge exchange due to collisions with residual gas molecules. Since the charge exchange process changes the magnetic rigidity, the involved ions are lost behind dispersive elements, and an energy-dependent gas desorption takes place. The StrahlSim code has been used to predict the stability of the residual gas pressure in SIS100 under beam loss driven dynamic conditions. The results show, that a stable operation at highest U²⁸⁺ intensities is possible, under the constraint that the vacuum chambers of the ion catcher system are cold enough to pump hydrogen. Furthermore, in order to determine the load to the cryogenic system, the average beam energy deposition onto the ion catcher system has been calculated.

WEPS096	Injection Energy Recovery of J-PARC RCS	power-supply, injection, impedance, septum	2730
	N. Hayashi, H. Hotchi, J. Kamiya, P.K. Saha, T. Takayanagi, K. Yamamoto, M. Yamamoto, Y. Yamazaki JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	The J-PARC RCS is a high beam power Rapid-Cycling Synchrotron (RCS). The original designed injection energy is 400MeV, although presently it is 181MeV, and its beam power is limited to 0.6MW. Works to recover the Linac energy are ongoing and injection magnets power supplies upgrade are required in the RCS. In order to achieve 1MW designed beam power, new instrumentation is also planned simultaneously. Activities related injection energy recovery in the J-PARC RCS is presented.

WEPS097	Performance of Multi-harmonic RF Feedforward System for Beam Loading Compensation in the J-PARC RCS	cavity, impedance, beam-loading, acceleration	2733
	F. Tamura, M. Nomura, A. Schnase, T. Shimada, M. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan K. Hara, C. Ohmori, M. Toda, M. Yoshii KEK/JAEA, Ibaraki-Ken, Japan K. Hasegawa KEK, Tokai, Ibaraki, Japan
	The beam loading compensation is a key part for acceleration of high intensity proton beams in the J-PARC RCS. In the wide-band MA-loaded RF cavity, the wake voltage consists of not only the accelerating harmonic component but also the higher harmonics. The higher harmonic components cause the RF bucket distortion. We employ the RF feedforward method to compensate the multi-harmonic beam loading. The full-digital feedforward system is developed, which compensates the first three harmonic components of the beam loading. We present the results of the beam test with a high intensity proton beam (2.5·10¹³ ppp). The impedance seen by the beam is greatly reduced, the impedance of the fundamental accelerating harmonic is reduced to less than 25 ohms in a full accelerating cycle, while the shunt resistance of the cavity is in the order of 800 ohms. The performance of the feedforward system is promising for achievement of the design beam power, 1 MW, in the future.

THOAA03	Overview of LHC Beam Loss Measurements	luminosity, quadrupole, proton, collimation	2854
	B. Dehning, A.E. Dabrowski, M. Dabrowski, E. Effinger, J. Emery, E. Fadakis, V. Grishin, E.B. Holzer, S. Jackson, G. Kruk, C. Kurfuerst, A. Marsili, M. Misiowiec, E. Nebot Del Busto, A. Nordt, A. Priebe, C. Roderick, M. Sapinski, C. Zamantzas CERN, Geneva, Switzerland E. Griesmayer CIVIDEC Instrumentation, Wien, Austria
	The LHC beam loss monitoring system based on ionization chambers is used for machine protection, quench prevention and accelerator optimization. After one full year of operation it can be stated that its main functionality, that of the protection of equipment, has proven to be very robust with no issues observed for hundreds of critical beam loss events and the number of false beam aborts well below expectation. In addition the injection, dump and collimation system make regular use of the published loss measurements for system analysis and optimisation, such as the determination of collimation efficiency in order to identify possible intensity limitations as early as possible. Intentional magnet quenches have been performed to verify both the calibration accuracy of the system and the accuracy of the loss pattern predictions from simulations. Tests have also been performed with fast loss detectors based on single- and polycrystalline CVD diamond, which are capable of providing nanosecond resolution time loss structure. This presentation will cover all of these aspects and give an outlook on future performance.
	Slides THOAA03 [1.972 MB]

THOBB03	Research and Development of Novel Advanced Materials for Next-generation Collimators	impedance, radiation, target, collimation	2888
	A. Bertarelli, G. Arnau-Izquierdo, F. Carra, A. Dallocchio, M. Gil Costa, N. Mariani CERN, Geneva, Switzerland
	Funding: This work has partly been carried out through the European Coordination for Accelerator Research and Development (EuCARD), co-sponsored by EU 7th Framework Program. The study of innovative collimators is essential to handle the high energy particle beams required to explore unknown territory in basic research. This calls for the development of novel advanced materials, as no existing metal-based or carbon-based material possesses the combination of physical, thermal, electrical and mechanical properties, imposed by collimator extreme working conditions. A new family of materials, with promising features, has been identified: metal-diamond composites. These materials are to combine the outstanding thermal and physical properties of diamond with the electrical and mechanical properties of metals. The best candidates are Copper-Diamond (Cu-CD) and Molybdenum-Diamond (Mo-CD). In particular, Mo-CD may provide interesting properties as to mechanical strength, melting temperature, thermal shock resistance and, thanks to its balanced material density, energy absorption. The research program carried out on these materials at CERN and collaborating partners is presented, mainly focusing on the theoretical investigation, material characterization, and manufacturing processes.
	Slides THOBB03 [3.948 MB]

THPC006	Experiments to Measure Electron Beam Energy using Spin Depolarization Method on SOLEIL Storage Ring	polarization, storage-ring, electron, synchrotron	2915
	J.F. Zhang, L. Cassinari, M. Labat, A. Nadji, L.S. Nadolski, D. Pédeau SOLEIL, Gif-sur-Yvette, France
	The electron beam energy on SOLEIL storage ring was successfully measured using spin depolarization method after several attempts over the past few years. The experimental results demonstrate that the effective polarization was 91.3%±3% and polarization time was 17±2.3 minutes as expected from the simulation using SLIM code. The beam was depolarized using an AC shaker and the depolarization was monitored using DCCT and beam loss monitors. The beam energy was measured with accuracy up to a few 10^-5.

THPC070	An Automated Statistical Analysis Package for the Study of Synchrotron Light Source Operation	cavity, storage-ring, monitoring, synchrotron	3056
	C. Christou, C.P. Bailey, V.C. Kempson, V.J. Winter Diamond, Oxfordshire, United Kingdom
	Machine faults and interruptions to user beam at Diamond Light Source are recorded in a Fault Log Database (FLDB) running under Microsoft Access. The scope of numerical analysis in Access is limited, and so an advanced data analysis package has been written in Matlab to exploit the powerful numeric functions available in this environment to automatically analyze machine faults and summarize data for reliability reports. Figures of merit such as mean time between failure (MTBF), mean time to repair (MTTR), total up time and total number of faults over the machine as a whole and by technical group can be calculated, and more advanced Pareto and Weibull analyses can be instantly generated. Data is presented for Diamond Light Source both for the latest year of operation and since user beam began in 2007, and the impact of different technical groups, in particular the storage ring RF, is considered. Failure distributions and the underlying hazard functions are produced and compared with statistical models to highlight deviations from randomly occurring events and to quantify changes in failure probability with time.

THPS035	Collimator Upgrade Plan of the J-PARC Main Ring	radiation, injection, collimation, septum	3496
	M.J. Shirakata, K. Ishii, C. Kubota, T. Oogoe, J. Takano KEK, Ibaraki, Japan Y. Kuniyasu MELCO SC, Tsukuba, Japan Y. Takiyama JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	A halo collimation system is prepared in the middle of injection-straight section in order to localize the beam loss occurred in main ring. It consists of three collimator units. The first unit scatters halo components, and the other two units work as halo catchers. The permitted amount of beam losses in the collimator section is designed to be 450 W at the present. The upgrade plan of halo collimation system is running in order to achieve about ten times larger beam loss capability for high-power beam operation. The collimator upgrade is planned by installing a new collimator set and radiation shields which cover the collimator section. New collimator units are designed to be able to line-out the jaw with a part of radiation shield including the mechanical devices. The design work of collimator units and radiation shields is presented in this report.

THPS040	Measurement of the Stripping Efficiency for HBC Stripper Foil in the 3-GeV RCS of J-PARC	injection, extraction, proton, scattering	3511
	P.K. Saha, H. Harada, S. Hatakeyama, H. Hotchi, M. Kinsho, Y. Yamazaki, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan Y. Irie, I. Sugai KEK, Ibaraki, Japan
	We have carried out experimental measurement of the stripping efficiency for the newly developed HBC (Hybrid type Boron doped Carbon) stripper foils. The HBC foil is used for charge-exchange injection in the RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex) and plays an important role for the RCS operation. We have developed a rather simple but very precise method using which stripping efficiencies for several HBC foils were determined accurately. Importance of knowing an accurate stripping efficiency so as to determine a realistic stripper foil for the RCS operation will be discussed.

THPS042	Feasibility Studies of the Foil Scattering Extraction in CSNS/RCS	extraction, scattering, simulation, proton	3517
	N. Wang, M.Y. Huang, N. Huang, S. Wang IHEP Beijing, Beijing, People's Republic of China
	A slow extraction based on foil scattering was suggested in the rapid cycling synchrotron of China Spallation Neutron Source for particle calibration. Protons with large scattering angle will be extracted during 2 ms at the end of each beam cycle, via a carbon foil. The feasibility of the extraction scheme is investigated. The extraction efficiency is studied by both single turn and multi-turn simulations with FLUKA and ORBIT, respectively. Beam losses due to multiple scattering to the downstream components are predicted.

THPS053	Results from the HiRadMat Primary Beam Line Commissioning	optics, proton, controls, instrumentation	3547
	C. Heßler, M. Arruat, J. Bauche, K. Bestmann, J. Blanco, N. Conan, K. Cornelis, I. Efthymiopoulos, H. Gaillard, B. Goddard, D. Grenier, G.G. Gros, A. Habert, L.K. Jensen, V. Kain, G. Le Godec, M. Meddahi, S. Pelletier, P. Pepinster, B. Puccio, C. Theis, P. Trilhe, G. Vandoni, J. Wenninger CERN, Geneva, Switzerland
	The High Radiation to Materials facility (HiRadMat) is a new experimental area at CERN, for studies of the impact of high-intensity pulsed beams on accelerator components and materials. The beam is delivered from the SPS by a new primary beam line, which has been constructed during the 2010/11 winter technical stop. The paper summarizes the construction phase and describes the results from the beam line commissioning in spring 2011. Beam parameter and aperture measurements are presented, as well as steering tests. A special emphasis has been put on the handling of the exceptionally flexible beam line optics in the control system.

THPS055	Controlling Beamloss at Injection into the LHC	injection, emittance, kicker, shielding	3553
	B. Goddard, F. Alessio, W. Bartmann, P. Baudrenghien, V. Boccone, C. Bracco, M. Brugger, K. Cornelis, B. Dehning, A. Di Mauro, L.N. Drosdal, E.B. Holzer, W. Höfle, R. Jacobsson, V. Kain, M. Meddahi, V. Mertens, A. Nordt, J.A. Uythoven, D. Valuch, S. Weisz, E.N. del Busto CERN, Geneva, Switzerland R. Appleby UMAN, Manchester, United Kingdom
	Losses at injection into the superconducting LHC can adversely affect the machine performance in several important ways. The high injected beam intensity and energy mean that precautions must be taken against damage and quenches, including collimators placed close to the beam in the injection regions. Clean injection is essential, to avoid spurious signals on the sensitive beam loss monitoring system which will trigger beam dumps. In addition, the use of the two injection insertions to house downstream high energy physics experiments brings constraints on permitted beam loss levels. In this paper the sources of injection beam loss are discussed together with the contributing factors and various issues experienced in the first full year of LHC operation. Simulations are compared with measurement, and the implemented and planned mitigation measures and diagnostic improvements are described. An outlook for future LHC operation is given.

THPZ026	Collimation Dependent Beam Lifetime and Loss Rates in the LHC	collimation, luminosity, insertion, betatron	3744
	D. Wollmann, R.W. Assmann, R. Bruce, F. Burkart, M. Cauchi, D. Deboy, S. Redaelli, A. Rossi, G. Valentino CERN, Geneva, Switzerland
	The four primary collimators in each LHC beam define the smallest aperture. Particles with high betatron amplitudes or momentum offset will therefore hit first a primary collimator. The instantaneous particle loss rate at primary collimators is an important measure for the global lifetime of the beams and a major ingredient to identify collimation induced performance limitations in the LHC. These loss rates have been measured during a number of LHC fills, featuring both "good" fills with high luminosity and "bad" fills with beam instabilities. The beam lifetime at the collimators was then calculated from this data for different cases. The results are presented and interpreted within this paper.

THPZ027	First Beam Results for a Collimator with In-jaw Beam Position Monitors	collimation, alignment, proton, closed-orbit	3747
	D. Wollmann, O. Aberle, R.W. Assmann, A. Bertarelli, C.B. Boccard, R. Bruce, F. Burkart, M. Cauchi, A. Dallocchio, D. Deboy, M. Gasior, O.R. Jones, S. Redaelli, A. Rossi, G. Valentino CERN, Geneva, Switzerland
	With more than 100 collimators the LHC has the most complex collimation system ever installed in an accelerator. The beam-based setup time of the system was a non-negligible factor during the commissioning of the LHC. In addition if the particle orbit at a collimator goes out of tolerance, this collimator needs to be setup again. To reduce the required setup time for the collimation system and to obtain the tight tolerances required for the LHC operation with small beta* and high beam energy, a new collimator design is being developed that integrates a beam position monitor (BPM) into the jaws of the collimator. A prototype of such a phase-II LHC collimator was installed in the SPS at CERN for the 2010 run. In this paper we present the first experimental results from the beam tests performed.

THPZ029	Principles for Generation of Time-dependent Collimator Settings during the LHC Cycle	injection, optics, collimation, controls	3753
	R. Bruce, R.W. Assmann, S. Redaelli CERN, Geneva, Switzerland
	The settings of the LHC collimators have to be changed during the cycle of injection, ramp and squeeze to account for variations in the orbit, beam size and normalized distance to the beam center. We discuss the principles for how the settings are calculated and show a software tool that computes them as time-dependent functions from beam-based data and theoretical optics models.

THPZ030	Halo Scrapings with Collimators in the LHC	collimation, luminosity, superconducting-magnet, proton	3756
	F. Burkart, R.W. Assmann, R. Bruce, M. Cauchi, D. Deboy, S. Redaelli, A. Rossi, G. Valentino, D. Wollmann CERN, Geneva, Switzerland L. Lari IFIC, Valencia, Spain
	The population of the beam halo has been measured in the LHC with beam scraping experiments. Primary collimators of the LHC collimation system were used to scrape the beam halo at different statuses of the machine (injection, top energy, separated and colliding beams). In addition these measurements were used to calibrate the beam loss monitor signals to loss rates at the primary collimators. Within this paper the halo scraping method, the measured halo distribution and the calibration factors are presented and compared to theoretical predictions.

THPZ031	Acoustic Measurements in the Collimation Region of the LHC	background, radiation, collimation, proton	3759
	D. Deboy, R.W. Assmann, C. Baccigalupi, F. Burkart, M. Cauchi, C.S. Derrez, J. Lendaro, A. Masi, S. Redaelli, G. Spiezia, D. Wollmann CERN, Geneva, Switzerland
	The LHC accelerator at CERN has the most advanced collimation system ever being installed. The collimators intercept unavoidable particle losses and therefore are essential to avoid beam induced quenches of the superconducting magnets. In addition, they provide passive machine protection against mis-kicked beams. During material robustness tests on a LHC collimator prototype in 2004 and 2006, vibration and acoustic measurements have shown that a beam impact detection system should be feasible using accelerometers and microphones as sensors in the LHC. Recently, such sensors have been installed close to the primary collimators in the LHC tunnel. First analyses of raw data show that the system is sensitive enough to detect beam scraping on collimators. Therefore, the implementation of a sophisticated acoustic monitoring system is under investigation. It may be useful not only to detect beam impacts on primary collimators in case of failure, but also to derive further information on beam losses that occur during regular operation. This paper gives an overview on the recent installation, results of the acoustic measurements made at the LHC, and future plans.

THPZ032	Evaluation of the Combined Betatron and Momentum Cleaning in Point 3 in Terms of Cleaning Efficiency and Energy Deposition for the LHC Collimation Upgrade	betatron, collimation, quadrupole, proton	3762
	L. Lari, R.W. Assmann, V. Boccone, M. Brugger, F. Cerutti, A. Ferrari, A. Rossi, R. Versaci, V. Vlachoudis, D. Wollmann CERN, Geneva, Switzerland A. Faus-Golfe, L. Lari IFIC, Valencia, Spain A. Mereghetti UMAN, Manchester, United Kingdom
	Funding: This work has been carried out through of the European Coordination for Accelerator Research and Development (EuCARD), co-sponsored by EU 7th Framework Program. The Phase I LHC Collimation System Upgrade could include moving part of the Betatron Cleaning from LHC Point 7 to Point 3 to improve both operation flexibility and intensity reach. In addition, the partial relocation of beam losses from the current Betatron cleaning region at Point 7 will mitigate the risks of Single Event Upsets to equipment installed in adjacent and partly not adequate shielded areas. A combined Betatron and Momentum Cleaning scenario at Point 3 implies the installation of new collimators and a new collimator aperture layout. This paper shows the whole LHC Collimator Efficiency variation with the new layout proposed at different beam energies. As part of the evaluation, energy deposition distribution in the IR3 region gives indications about the effect of this new implementation not only on the collimators themselves but also on the other beam line elements.

THPZ034	Semi-automatic Beam-based Alignment Algorithm for the LHC Collimation System	alignment, controls, collimation, feedback	3768
	G. Valentino, R.W. Assmann, S. Redaelli, N.J. Sammut, D. Wollmann CERN, Geneva, Switzerland G. Valentino University of Malta, Information and Communication Technology, Msida, Malta
	Full beam-based alignment of the LHC collimation system was a lengthy procedure as the collimators were set up manually. A yearly alignment campaign has been sufficient for now, although in future this may lead to a decrease in the cleaning efficiency if machine parameters such as the beam orbit drift over time. Automating the collimator setup procedure can allow for more frequent alignments, therefore reducing this risk. This paper describes the design and testing of a semi-automatic algorithm as a first step towards a fully automatic setup. Its implementation in the collimator control software and future plans are described.

THPZ035	Comparison of LHC Collimation Setups with Manual and Semi-automatic Collimator Alignment	alignment, collimation, injection, insertion	3771
	G. Valentino, R.W. Assmann, R. Bruce, F. Burkart, M. Cauchi, D. Deboy, S. Redaelli, A. Rossi, N.J. Sammut, D. Wollmann CERN, Geneva, Switzerland G. Valentino University of Malta, Information and Communication Technology, Msida, Malta
	The LHC collimation system beam-based alignment procedure has recently been upgraded to a semi-automatic process in order to increase its efficiency. In this paper, we describe the parameters used to measure the accuracy, stability and performance of the beam-based alignment of the LHC collimation system. This is followed by a comparison of the results at 450 GeV and 3.5 TeV with (1) a manual alignment and (2) with the results for semi-automatic alignment.

FRXCA01	First Years Experience of LHC Beam Instrumentation	feedback, emittance, instrumentation, luminosity	3779
	O.R. Jones CERN, Geneva, Switzerland
	The LHC is equipped with a full suite of sophisticated beam instrumentation which has been essential for rapid commissioning, the safe increase in total stored beam power and the understanding of machine optics and accelerator physics phenomena. This talk will comment on all of these systems and on their contributions to the various stages of beam commissioning. It will include details on: the beam position system and its use for real-time global orbit feedback; the beam loss system and its role in machine protection; total and bunch by bunch intensity measurements; tune measurement and feedback; synchrotron light diagnostics for transverse beam size measurements, abort gap monitoring and longitudinal density measurements. Issues and problems encountered along the way will also be discussed together with the prospect for future upgrades.
	Slides FRXCA01 [7.322 MB]

Paper

Title

Other Keywords

Page

MOXBA01

J-PARC Beam Commissioning Progress

injection, linac, extraction, vacuum

6

H. Hotchi
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

The J-PARC is a multi-purpose proton accelerator facility amiming at MW-class output beam power, consisting of a 400 MeV H⁻ linac, a 3-GeV RCS, a 50-GeV MR (Main Ring) and three experimental facilities, the MLF (materials and life science experimental facility), the HD (hadron experimental hall) and the NU (neutrino beam line). The J-PARC beam commissioning started in November 2006 from the linac to the downstream facilities. The current output beam power from the RCS to the MLF users is 210 kW, and the MR delivers 145 kW beam to the NU by fast extraction and a few kW beam to the HD by slow extraction. In this talk, we present a current status of the J-PARC beam commissioning, in which a recent progress in the course of the RCS beam power ramp-up scenario will be described in more detail. This talk will focus on the issues (including beam dynamics), challenges, solutions, and lessons learned during the commissioning and user operation of J-PARC and future plans.

Slides MOXBA01 [2.615 MB]

MOODB02

RF Modeling Plans for the European Spallation Source

cavity, HOM, electron, linac

56

S. Molloy, M. Lindroos, S. Peggs
ESS, Lund, Sweden
R. Ainsworth
Royal Holloway, University of London, Surrey, United Kingdom
R.J.M.Y. Ruber
Uppsala University, Uppsala, Sweden

The European Spallation Source (ESS) will be the world's most powerful next generation neutron source. The ESS linac is designed to accelerate highly charged bunches of protons to a final energy of 2.5 GeV, with a design beam power of 5 MW, for collision with a target used to produce the high neutron flux. In order to achieve this several stages of RF acceleration are required, each using a different technology. The high beam current and power require a high degree of control of the accelerating RF, and the specification that no more than 1 W/m of losses will be experienced means that the excitation and decay of the HOMs must be very well understood. Experience at other high power machines also implies that an understanding of the generation and subsequent trajectories of any field-emitted electrons should be understood. Thermal detuning of the HOM couplers due to multipacting is a serious concern here. This paper will outline the RF modeling plans - including the construction of mathematical models, simulations of HOMs, and multipacting - during the current Accelerator Design Update phase, and will discuss several of the more important issues for ESS.

Slides MOODB02 [48.641 MB]

MOPC089

RF Simulations for the QWR Cavities of PIAVE-ALPI

cavity, simulation, ion, linac

283

M. Comunian, F. Grespan, A. Palmieri
INFN/LNL, Legnaro (PD), Italy

The PIAVE-ALPI linac is composed of several families of QWR cavities. In order to have a thorough description of the accelerator in terms of beam dynamics, a detailed field mapping of the accelerating cavities is necessary, including non-linear behavior of the off-axis fields, as well as the steering and dispersion effects due to transverse components. For such a purpose, a set of RF simulation was accomplished, with the codes HFSS and COMSOL. The details about these simulations and the main outcomes and results will be described in this article.

MOPO011

The First 1 1/2 Years of TOTEM Roman Pot Operation at LHC

alignment, controls, HOM, scattering

502

M. Deile, G.H. Antchev, R.W. Assmann, I. Atanassov, V. Avati, J. Baechler, R. Bruce, M. Dupont, K. Eggert, B. Farnham, J. Kaspar, F. Lucas Rodríguez, J. Morant, H. Niewiadomski, X. Pons, E. Radermacher, S. Ravat, F. Ravotti, S. Redaelli, G. Ruggiero, H. Sabba, M. Sapinski, W. Snoeys, G. Valentino, D. Wollmann
CERN, Geneva, Switzerland
R. Appleby
UMAN, Manchester, United Kingdom

Since the LHC running season 2010, the TOTEM Roman Pots (RPs) are fully operational and serve for collecting elastic and diffractive proton-proton scattering data. Like for other moveable devices approaching the high intensity LHC beams, a reliable and precise control of the RP position is critical to machine protection. After a review of the RP movement control and position interlock system, the crucial task of alignment will be discussed.

MOPS002

Mitigation of Space Charge and Nonlinear Resonance Induced Beam Loss in SIS100

resonance, space-charge, acceleration, simulation

589

G. Franchetti
GSI, Darmstadt, Germany

The control of beam loss in SIS100 is essential for avoiding vacuum instability and guarantee the delivery of the foreseen beam intensity. On the other hand simulations show that the simultaneous presence of space charge and lattice resonances creates during 1 second cycle a progressive beam loss exceeding the limit of 5%. Until now the mechanism of periodic resonance crossing were suspected to be, in conjunction with pure dynamic aperture effects, at the base of the beam loss. In this proceeding we present the state of the art in the beam loss prediction and we prove that the periodic resonance crossing is the deteriorating mechanism, and show that the compensation of a relevant resonance intercepting the space charge tune spread sensibly mitigate the beam loss. A short discussion on beam loss during acceleration is addressed as well.

MOPS005

Beam Dynamics Simulations of J-PARC Main Ring for Upgrade Plan of Fast Extraction Operation

simulation, injection, proton, power-supply

598

Y. Sato, K. Hara, S. Igarashi, T. Koseki, K. Ohmi, C. Ohmori, M. Tomizawa
KEK, Ibaraki, Japan
H. Hotchi
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

Beam loss simulations under space charge effects are necessary to seek higher intensity proton beams. This paper presents simulations for fast extraction operation of Japan Proton Accelerator Research Complex (J-PARC) Main Ring. For upgrade plan, increasing protons per bunch and making higher repetition pattern are considered. Their optimal balance is discussed to minimize beam losses for aimed beam power considering space charge effects. We found that to optimize RF voltage pattern is a strong key to reduce beam losses for higher repetition. As benchmark works, we compare our simulations with the measured beam loss in our past operation.

MOPS014

Tune and Space Charge Studies for High-brightness and High-intensity Beams at CERN PS

resonance, emittance, space-charge, injection

625

S.S. Gilardoni, S. Aumon, J. Brenas, P. Freyermuth, A. Huschauer, R. Maillet, E. Matli, R.R. Steerenberg, B. Vandorpe
CERN, Geneva, Switzerland
E. Benedetto
National Technical University of Athens, Zografou, Greece

The current 1.4 GeV CERN PS injection energy limits the maximum intensity required by the future High-Luminosity LHC. The bare-machine large chromaticity combined with the non-linear space charge forces make high-brightness and high-intensity beams crossing betatron resonances along the injection flat bottom, inducing transverse emittance blow-up and beam losses. A scan of the working point plane {Qx,Qy} was done in order to identify beam destructive resonances, in the framework of a possible 2 GeV injection energy upgrade which would reduce the space charge effect on the tune. Experiments were carried out in order to review the maximum space charge tune shift for which no transverse emittance blow-up is observed. The results of measurements and simulations will be presented in this paper.

MOPS017

Simulation Studies of Macro-particles Falling into the LHC Proton Beam

proton, simulation, injection, vacuum

634

F. Zimmermann, T. Baer, M. Giovannozzi, E.B. Holzer, E. Nebot Del Busto, A. Nordt, M. Sapinski
CERN, Geneva, Switzerland
N. Fuster
Valencia University, Atomic Molecular and Nuclear Physics Department, Valencia, Spain
Z. Yang
EPFL, Lausanne, Switzerland

We report updated simulations on the interaction of macro-particles falling from the top of the vacuum chamber into the circulating LHC proton beam. The path and charge state of micron size micro-particles are computed together with the resulting beam losses, which – if high enough - can lead to the local quench of SC magnets. The simulated time evolution of the beam loss is compared with observations in order to constrain some macro-particle parameters. We also discuss the possibility of a "multiple crossing" by the same macro-particle, the effect of a strong dipole field, and the dependence of peak loss rate and loss duration on beam current and on beam size.

MOPS071

Simulations of the Impedance of the New PS Wire Scanner Tank

simulation, impedance, extraction, vacuum

766

B. Salvant
EPFL, Lausanne, Switzerland
W. Andreazza, F. Caspers, A. Grudiev, J.F. Herranz Alvarez, E. Métral, G. Rumolo
CERN, Geneva, Switzerland

The CERN PS is equipped with 4 wire scanners. It was identified that the small aperture of the current wire scanner tank causes beam losses and a new tank design was needed. The interaction of the PS bunches with the beam coupling impedance of this new tank may lead to beam degradation and wire damage. This contribution presents impedance studies of the current PS tank as well as the new design in order to assess the need to modify the design and/or install lossy materials plates dedicated to damp higher order cavity modes and reduce the total power deposited by the beam in the tank.

MOPS074

Stabilization of the LHC Single-bunch Transverse Instability at High-energy by Landau Octupoles

octupole, simulation, emittance, single-bunch

775

E. Métral, B. Salvant
CERN, Geneva, Switzerland
N. Mounet
EPFL, Lausanne, Switzerland

When the first ramp was tried on Saturday 15/05/2010 with a single bunch of about nominal intensity (i.e. ~ 10¹1 p/b), the bunch became unstable in the horizontal plane at ~ 2 TeV. The three main observations were: (i) a “Christmas tree” in the transverse tune measurement application (with many synchrotron sidebands excited), (ii) beam losses (few tens of percents) in IR7, and (iii) an increase of the bunch length. This transverse coherent instability has been stabilized successfully with Landau octupoles. Comparing all the measurements performed during this first year of LHC commissioning with the theoretical and simulation predictions reveals a good agreement.

MOPZ002

MICE Beamline

dipole, emittance, solenoid, target

823

Y. Karadzhov
DPNC, Genève, Switzerland

The muon ionization cooling experiment (MICE) is under development at the Rutherford Appleton Laboratory (UK). The goal of the experiment is to build a section of a muon cooling channel that can demonstrate the principle of Ionization cooling over a range of emittances and momenta. The MICE beam line must generate several matched muon beams with different momenta and optical parameters at the entrance of the cooling channel. This is done exploiting a titanium target dipping into the ISIS proton beam, a 5T superconducting pion decay solenoid, two dipole magnets and a mechanism for inflation of the initial emittance called diffuser. First measurements of muon rates and beam emittance performed using two TOF hodoscopes detectors will be presented.

MOPZ035

MICE Muon Beamline Particle Rate and Related Beam Loss in the ISIS Synchrotron

target, proton, synchrotron, solenoid

874

A.J. Dobbs
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
D. Adey
University of Warwick, Coventry, United Kingdom
L. Coney
UCR, Riverside, California, USA

The international Muon Ionization Cooling Experiment (MICE) will provide a proof of principle of ionization cooling, reduction of muon beam phase space, which will be needed at a future Neutrino Factory and Muon Collider. The MICE muon beam is generated by the decay of pions produced by dipping a cylindrical titanium target into the proton beam of the 800 MeV ISIS synchrotron at the Rutherford Appleton Laboratory, U.K. Studies of the particle rate in the MICE beamline and correlations with induced beam loss in ISIS are described, including the most recent data taken in the summer of 2010, representing some of the highest loss and rate conditions achieved to date. Ideally, a high rate of muons in the MICE beamline is desired, in order to facilitate the cooling measurement. However, impact on the host accelerator equipment must also be minimized. The implications of the observed beam loss and particle rate levels for MICE and ISIS are discussed.

TUOAA02

Status of UA9, the Crystal Collimation Experiment in the SPS

collimation, ion, proton, simulation

897

W. Scandale
LAL, Orsay, France

Funding: CERN, IHEP-Protvino, Imperial-College, INFN, JINR-Dubna, LBNL, PNPI-Gartchina, SLAC
UA9 was operated in the CERN-SPS for more than two years in view of investigating the feasibility of the halo collimation with bent crystals. Silicon crystals 2 mm long with bending angles of about 150 urad were used as primary collimators. The crystal collimation process was steadily achieved through channeling with high efficiency. The crystal orientation was easily set and optimized with the installed goniometer which has an angular reproducibility of about ± 10 μrad. In channeling orientation, the loss rate of the halo particles interacting with the crystal is reduced by a factor of ten, whilst the residual off-momentum halo escaping from the crystal-collimator area is reduced by a factor five. The crystal channeling efficiency of about 75 % is reasonably consistent with simulations and with single pass data collected in the North Area of the SPS. The accumulated observations, shown in this paper, support our expectation that the coherent deflection of the beam halo by a bent crystal should considerably help in enhancing the collimation efficiency in LHC.

Slides TUOAA02 [4.297 MB]

TUPC039

Proposals for Electron Beam Transportation Channel to Provide Homogeneous Beam Density Distribution at a Target Surface

target, electron, neutron, quadrupole

1084

A.Y. Zelinsky, I.M. Karnaukhov
NSC/KIPT, Kharkov, Ukraine
W.B. Liu
IHEP Beijing, Beijing, People's Republic of China

NSC KIPT neutron source will use 64x64 mm rectangular tungsten or uranium target. To generate maximum neutron flux, prevent overheating of the target and reduce thermal stress one should provide homogeneous electron beam distribution at the target surface. In the facility transportation channel three different possibilities of electron beam density redistribution along the target surface can be realized. It can be the fast beam scanning with two dimensional scanning magnets; the method of uniform beam distribution formation with linear focusing elements (dipole and quadrupole magnets) and nonlinear focusing elements (octupole magnets), when final required rectangular beam shape with homogeneous beam density is formed at target; and combined method, when one forms the small rectangular beam with homogeneous beam density distribution and scan it over the target surface with scanning magnets. In the report the all tree methods are considered and discussed considering the layout of the NSC KIPT transportation channel. Calculation results show that the proposed transportation channel lattice can provide uniform beam of rectangular shape with sizes 64x64 mm without target overheating.

TUPC070

SAFARI, an Optimized Beam Stop Device for High Intensity Beams at the SPIRAL2 Facility

linac, beam-transport, neutron, vacuum

1162

E. Schibler
IN2P3 IPNL, Villeurbanne, France
L. Perrot
IPN, Orsay, France

The SPIRAL2 facility at GANIL-Caen is now in its construction phase, with a project group including the participation of many French laboratories (CNRS, CEA) and international partners. The facility will be able to produce various accelerated beams at high intensities: 40 MeV Deuterons, 33 MeV Protons with intensity until 5mA and heavy ions with A/Q=3 up to 14.5MeV/u until 1mA current. We will present the final status of the 200kW beam stop located in the high energy beam transport lines. From the beam characteristics (HEBT line up to beam stop) and activation constraints, we studied and developed a complete design of a new high efficiency Beam Stop that has been nicknamed SAFARI (Système Arrêt Faisceau Adapté Rayons Intenses - Optimized Beam Stop Device for High Intensity Beams). Special focus will be done on the adequacy between beam dynamic and thermo-mechanical behavior. The Beam Stop shape marries to the beam characteristics in order to smooth for the best power density and improve thermo-mechanical behavior under nominal and critical beams. Optimization by various fluids studies and calculations led us to a new high efficiency counter-current water cooling system.

TUPC083

Comparative Studies into 3D Beam Loss Simulations

simulation, photon, electron, positron

1198

M. Panniello
MPI-K, Heidelberg, Germany
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: Work supported by the Helmholtz Association and GSI under contract VH-NG-328.
A detailed understanding and monitoring of potential beam loss mechanisms is crucial for every particle accelerator. The main motivation in low energy facilities, such as the Ultra-low energy Storage Ring (USR) at the future Facility of Low energy Antiproton and Ion Research (FLAIR), comes from the very low number of particles available which in such machine ought to be conserved. In High Energy accelerators it is the concern about activation or even physical damage of machine parts which has to be taken into serious account. The CLIC Test Facility (CTF3) at CERN provides an ideal testing ground for studies into novel BLM systems and is well suited for benchmarking the results from numerical simulations in experiments. This contribution summarizes the three-dimensional beam loss pattern as found with the commonly used codes FLUKA and Géant4. The results from these codes are compared and analyzed in detail and used for the identification of optimum beam loss monitor locations.

TUPC100

Longitudinal Beam Profile Measurement at J-PARC Separated Drift Tube Linac

cavity, linac, simulation, injection

1245

T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan
M. Ikegami
KEK, Ibaraki, Japan
A. Miura, G.H. Wei
JAEA/J-PARC, Tokai-mura, Japan
H. Sako
JAEA, Ibaraki-ken, Japan

We measured longitudinal beam profile at Separated Drift Tube Linac (SDTL) injection part by scanning beam transmission and beamloss at the downstream of SDTL section by changing SDTL injection phase. As the beam goes to acceptance edge, part of the beam which is out of acceptance isn't accelerate and finally it is lost by hitting to beam duct. Thus beam transmission shows sliced bunch shape by acceptance edge, it is possible to reconstruct the beam bunch shape. The result shows about 60% wider profile in both phi and E direction against to design.

TUPC102

Measurement of Beam Loss Tracks by Scintillating Fibers at J-PARC Linac

linac, background, simulation, gun

1251

H. Sako, T. Maruta, A. Miura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

Highest beam loss in the J-PARC linac has been observed that the ACS (Annular-Coupled Structure linac) section. Since the observed beam loss is proportional to the residual gas pressure, the source of the beam loss is considered as H0 produced in an interaction of H⁻ beams with remnant gas. If this assumption is valid, H0 hits the beam duct and changes into H⁺ and escapes from the beam duct. We constructed scintillation fiber hodoscopes to detect H⁺s and eventually identify the particle species as H⁺. The hodoscopes are made of 4 planes of hodoscopes which consists of 16 scintillation fibers of 64mm long and with 4mmx4mm cross section. We installed the hodoscopes at the upstream part of the ACS section and measured beam loss. The results are shown in this paper.

TUPC104

Beam Loss Detected by Scintillation Monitor

linac, cavity, simulation, hadron

1257

A. Miura, K. Hasegawa, T. Maruta, N. Ouchi, H. Sako
JAEA/J-PARC, Tokai-mura, Japan
Z. Igarashi, M. Ikegami, T. Miyao
KEK, Ibaraki, Japan

Ar gas proportional BLMs have measured the beam loss through operations, but they are also sensitive to background noise of X-ray emitted from RF cavities. We have tried to measure the beam loss using scintillation monitors which would bring more accurate beam loss measurements with suppression of X-ray noise. We measured beam loss using scintillation beam loss monitors. Because this scintillation BLM is sensitive for low energy gamma-rays and fast neutrons, small signals from X-rays would be also detected. As the measurement results, a good signal to noise ratio is observed for the scintillation monitor with quite low sensitivity to the background X-ray. And many single events are observed in the intermediate pulse bunch with about 600 ns as pulse width. In addition, because we fabricated the filter and integrated circuit, total amount of X-ray noise can become smaller. We obtained the good performances of scintillation BLM with small effect of X-ray noise. This monitor can be used for beam loss measurement and a knob for tuning. Furthermore, because the detail structure can be detected, this monitor could be employed for another diagnostic device.

TUPC131

Overview of ESS Beam Loss Monitoring System

ion, proton, neutron, SRF

1329

L. Tchelidze, A. Jansson
ESS, Lund, Sweden

European Spallation Source (ESS) is a multi-MW proton linear accelerator that will be built in Lund, Sweden. Due to the high power of the machine, losses need to be minimized to avoid damaging the accelerator components and quenching superconducting magnets. Loss monitors have to be positioned all across the accelerator, so that they form a reliable protection system. A careful analysis of the loss nature for ESS is in progress to determine the locations for the loss detectors. This paper presents preliminary results of the simulations for the detector response functions, which are calculated for several different energies and incident angles of protons, at certain parts of the accelerator. A simple, baseline geometry configuration is used in the calculations. This paper also gives an overview of the considered ESS beam loss monitoring system. It describes the types of the detectors which are planned to be used at ESS, and discusses the number of detectors needed along different parts of the machine. As planned, a primary tool for measuring losses at ESS will be ionization chambers, the conceptual design of which is given in this paper based on the response time considerations.

TUPC135

Beam Loss Monitors Comparison at the CERN Proton Synchrotron

injection, radiation, electron, proton

1341

S.S. Gilardoni, S. Aumon, E. Effinger, J. Gil Flores
CERN, Geneva, Switzerland
U. Wienands
SLAC, Menlo Park, California, USA

CERN is planning the renovation and upgrade of the beam loss detection system for the Proton Synchrotron (PS). Improved performance in speed–to be able to monitor beam loss on a bunch-by-bunch basis–and in long-term stability–to reduce or avoid the need for periodic calibration–are aimed for. To select the most suitable technology, different detectors were benchmarked in the machine with respect to the same beam loss. The characteristics of the different detectors, the results of the measurement campaign and their suitability as future monitors for the PS are presented.

TUPC136

Analysis of Fast Losses in the LHC with the BLM System

injection, quadrupole, superconducting-magnet, proton

1344

E. Nebot Del Busto, T. Baer, B. Dehning, E. Effinger, J. Emery, E.B. Holzer, A. Marsili, A. Nordt, M. Sapinski, R. Schmidt, B. Velghe, J. Wenninger, C. Zamantzas, F. Zimmermann
CERN, Geneva, Switzerland
N. Fuster
Valencia University, Atomic Molecular and Nuclear Physics Department, Valencia, Spain
Z. Yang
EPFL, Lausanne, Switzerland

About 3600 Ionization Chambers are located around the LHC ring to detect beam losses that could damage the equipment or quench superconducting magnets. The BLMs integrate the losses in 12 different time intervals (from 40 us to 83.8 s) allowing for different abort thresholds depending on the duration of the loss and the beam energy. The signals are also recorded in a database at 1 Hz for offline analysis. During the 2010 run, a limiting factor in the machine availability were sudden losses appearing around the ring on the ms time scale and detected exclusively by the BLM system. It is believed that such losses originate from dust particles falling into the beam, or being attracted by its strong electromagnetic field. This document describes some of the properties of these "Unidentified Falling Objects" (UFOs) putting special emphasis on their dependence on beam parameters (energy, intensity, etc). The subsequent modification of the BLM beam abort thresholds for the 2011 run that were made to avoid unnecessary beam dumps caused by these UFO losses are also discussed.

TUPC137

UFOs in the LHC

injection, kicker, simulation, acceleration

1347

T. Baer, M.J. Barnes, B. Goddard, E.B. Holzer, J.M. Jimenez, A. Lechner, V. Mertens, E. Nebot Del Busto, A. Nordt, J.A. Uythoven, B. Velghe, J. Wenninger, F. Zimmermann
CERN, Geneva, Switzerland

One of the major known limitations for the performance of the Large Hadron Collider are so called UFOs (”Unidentified Falling Objects”). UFOs were first observed in July 2010 and have since caused numerous protection beam dumps. UFOs are thought to be micrometer sized dust particles which lead to fast beam losses with a duration of about 10 turns when they interact with the beam. In 2011, the diagnostics for such events was significantly improved which allows estimates of the properties, dynamics and production mechanisms of the dust particles. The state of knowledge and mitigation strategies are presented.

TUPC139

Overview of the CLIC Beam Instrumentation

linac, cavity, laser, instrumentation

1350

T. Lefèvre
CERN, Geneva, Switzerland

Driven by beam dynamic considerations the Compact Linear Collider (CLIC) is expected to require extremely tight tolerances on most beam parameters. An important milestone was reached in 2011 with the completion of the CLIC conceptual design report. In this context the requirements for CLIC beam instrumentation has been reviewed and studied in detail for the whole accelerator complex with the aim of demonstrating feasibility. A preliminary choice has been made for every CLIC instrument, serving as a baseline scenario for the next phase of the project which will concentrate on the detailed design, engineering and test of CLIC devices. Whenever possible existing solutions have been studied, focusing on any improvements necessary to meet the CLIC performance criteria. When no such devices exists, or if cost considerations come into play, new technologies have been under study. Several prototypes are already well advanced and are currently under test. This paper presents an overview of CLIC beam instrumentation, the possible reach of their performance and an outlook on future developments.

TUPC141

LHC Beam Loss Pattern Recognition

monitoring, proton, resonance, collider

1353

A. Marsili, E.B. Holzer, P.M. Puzo
CERN, Geneva, Switzerland

One of the systems protecting CERN's Large Hadron Collider (LHC) is the Beam Loss Monitoring system (BLM). More than 3600 monitors are installed around the ring. The beam losses are permanently integrated over 12 different time intervals (from 40 microseconds to 84 seconds). When any loss exceeds the thresholds defined for the integration window, the beam is removed from the machine. Understanding the origin of a beam loss is crucial for machine operation, as it can help to avoid a repeat of the same scenario. The signals read from given monitors can be considered as entries of a vector. This article presents how a loss map of unknown cause can be decomposed using vector based analysis derived from well-known loss scenarios. The algorithms achieving this decomposition are described, as well as the accuracy of the results.

TUPC142

The Particle Identification System for the MICE Beamline Characterization

emittance, electron, laser, solenoid

1356

M. Bonesini
INFN MIB, MILANO, Italy
Y. Karadzhov
DPNC, Genève, Switzerland

The International Muon Ionization Cooling Experiment (MICE) will carry out a systematic investigation of a ionization cooling section of a muon beam, for the future Neutrino Factory and the future Muon Collider. As the emittance measurement will be done on a particle-by-particle basis, a sophisticated beam instrumentation is needed to measure both particle coordinates and timing vs RF in a harsh environment due to high particle rates, fringe magnetic fields and RF backgrounds. A PID system, based on three time-of-flight stations (with resolutions up to 50-60 ps), two Aerogel Cerenkov counters and a KLOE-like calorimeter (KL) has been constructed and has allowed the commissioning of the MICE muon beamline in 2010. It will be complemented in 2011 by an Electron Muon Ranger to determine the muon range at the downstream end of the cooling section. Detector performances, as obtained in the 2010 run, will be shown and the use of PD detectors for the beamline characterization, including a preliminary measure of emittance, fully illustrated.

TUPC147

A Micro-Channel Plate Based Gas Ionization Profile Monitor with Shaping Field Electrodes for the ISIS H⁻ Injector

ion, controls, vacuum, radiation

1371

P.G. Barnes, G.M. Cross, B.S. Drumm, S.A. Fisher, S.J. Payne, A. Pertica, C.C. Wilcox
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

Beam profile measurements within the ISIS H⁻ injector line are achieved using destructive devices such as moving wire scanners. To avoid damage to the wires, measurements are made with the injector operating on reduced power. This paper reports the development of a Micro-Channel Plate based profile monitor which allows beam measurements to be made under normal operating conditions. The monitor produces profiles by measuring the +ion current resulting from the interaction of the H⁻ beam with the surrounding residual gas. The 32 channel Micro-Channel Plate is mounted on a rotating arm to enable it to be positioned parallel to the beam for calibration (all channels then measure the same +ion current) and perpendicular to the beam for profile measurements. A 15kV drift field is used together with field shaping electrodes to ensure a flat electric field gradient across the monitor, thereby minimising distortion of the profile due to the electric field. This paper details all aspects of the design and construction of this profile monitor. Beam profiles are compared to previous wire scanner results. Shaping field upgrades are discussed to improve the longitudinal field shape.

TUPC151

Cherenkov Fibre Optic Beam Loss Monitor at ALICE

photon, laser, electron, monitoring

1383

A. Intermite
The University of Liverpool, Liverpool, United Kingdom
A. Intermite, M. Putignano, A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom

The need for real-time monitoring of beam losses, including evaluation of their intensity and the localization of their exact position, together with the possibility to overcome the limitations due to the reduced space for the diagnostics, makes optical fibres (using the Cherenkov Effect) one of the most suitable and explored candidate for beam loss monitoring. In this contribution, we report on an optical fibre beam loss monitor based on large numerical aperture pure silicon fibres and silicon photomultipliers, tested at ALICE, Daresbury Laboratories, UK. The original design of the sensor has the advantage to combine the functions of a real time detector and a transmission line. It also allows reading the signals independently and determining the time and position of the losses without the use of an external trigger.

TUPC152

Comparative Study of Performance of Silicon Photomultipliers for Use in Cherenkov Fibre Optic Beam Loss Monitors

photon, electron, monitoring, lattice

1386

A. Intermite
The University of Liverpool, Liverpool, United Kingdom
A. Intermite, M. Putignano, A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Silicon Photomultipliers (SiPMs) are semiconductor photo-sensitive devices built from a matrix of Single Photon Avalanche Diodes (SPADs) on a common silicon substrate, working in the limited Geiger mode and with a common readout. The fast counting ability, high timing resolution, immunity to magnetic field up to 15 T, low power consumption and relative small temperature dependence together with the small dimensions make SiPMs excellent candidates as commercially available solid state detectors, and a promising alternative to traditional photomultiplier tubes for single photon detection. Nevertheless, SiPMs do suffer from erroneous counting due to noise effects that can deteriorate their performances. These effects are, in general, heavily dependent on manufacturing quality. In this contribution, results are reported of the characterization of different models of SiPMs in terms of noise spectra and response to light, and a procedure for determining quality manufacturing parameters is described.

TUPC153

Study of the Response of Silicon Photomultipliers in Presence of Strong Cross-talk Noise

photon, radiation, positron, heavy-ion

1389

M. Putignano, A. Intermite
The University of Liverpool, Liverpool, United Kingdom
M. Putignano, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: Work supported by STFC, the EU under GA-ITN-215080, the Helmholtz Association and GSI under VH-NG-328.
Silicon Photomultipliers (SiPM) are interesting detectors for beam diagnostics applications where they could replace photomultiplier tubes as large dynamic range photon counting devices due to their reduced dimensions and costs, higher photon detection efficiency, immunity to magnetic fields and low operation voltage. Possible applications include longitudinal beam profile measurements by synchrotron light imaging, detection of optical transition radiation for energy spectrum measurements and medical imaging. However, quantitative measurement with SiPMs are jeopardized by the systematic reading error due to Optical Cross-talk (OC), i.e. optical coupling between neighboring diodes in the array. OC results in overestimation of the impinging light level, and reflects the probability of a triggered avalanche creating a photon of suitable energy and direction to fire a second avalanche in another diode. In this paper, we derive a generalized response distribution for SiPM in presence of cross-talk noise, which overcomes the limitations of assumptions currently made in literature and provides a correction of the SiPM response distribution valid for arbitrary large levels of cross-talk.

TUPS007

Construction and Test of a Cryocatcher Prototype for SIS100*

ion, vacuum, heavy-ion, controls

1527

L.H.J. Bozyk, D.H.H. Hoffmann
TU Darmstadt, Darmstadt, Germany
H. Kollmus, P.J. Spiller, M. Wengenroth
GSI, Darmstadt, Germany

Funding: EU-FP-7 project COLMAT, FIAS
The main accelerator, SIS100, of the FAIR-facility will provide heavy ion beams of highest intensities. Ionization beam loss is the most important loss mechanism at operation with high intensity, intermediate charge state heavy ions. A special synchrotron design has been developed for SIS100, aiming for hundred percent control of ionization beam loss by means of a dedicated cold ion catcher system. To suppress dynamic vacuum effects, the cryo catcher system shall also provide a significantly reduced effective desorption yield. The construction and tests of a prototype cryo ion catcher is a workpackage of the EU-FP-7 project COLMAT. A prototype test setup including cryostat has been constructed, manufactured and tested at GSI under realistic conditions with heavy ion beams of the of the heavy ion synchrotron SIS18. The design and results are presented.

TUPS013

Development of the H0 Dump Branch Duct for the Additional Collimation System in J-PARC RCS

septum, shielding, collimation, vacuum

1545

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

For the new collimation system in the J-PARC RCS, we have the H0 branch duct installed at the dump septum magnet remodeled. This new branch duct is made of the two kinds of the stainless steels as follows; austenitic stainless steel, SUS316L and ferritic stainless steel, SUS430. In order to research on the property of the SUS430, test ducts were made in various heat-treating condition. In this presentation, we report the design of the new H0 branch duct and the study results with the test ducts.

TUPS037

Preliminary Assessment of Beam Impact Consequences on LHC Collimators

simulation, proton, collimation, controls

1617

M. Cauchi, R.W. Assmann, A. Bertarelli, R. Bruce, F. Carra, A. Dallocchio, D. Deboy, N. Mariani, A. Rossi, N.J. Sammut
CERN, Geneva, Switzerland
M. Cauchi, P. Mollicone
UoM, Msida, Malta
L. Lari
IFIC, Valencia, Spain

The correct functioning of the LHC collimation system is crucial to attain the desired LHC luminosity performance. However, the requirements to handle high intensity beams can be demanding. In this respect, the robustness of the collimators plays an important role. An accident which causes the proton beam to hit a collimator might result in severe beam-induced damage and, in some cases, replacement of the collimator, with consequent downtime for the machine. In this paper, several case studies representing different realistic beam impact scenarios are shown. A preliminary analysis of the thermal response of tertiary collimators to beam impact is presented, from which the most critical cases can be identified. Such work will also help to give an initial insight on the operational constraints of the LHC by taking into account all relevant collimator damage limits.

TUPS040

Driving the LHC Collimators' Stepping Motors over 1 km with High Accuracy avoiding EMI Effects

controls, feedback, impedance, radiation

1626

A. Masi, G. Conte, R. Losito, M. Martino
CERN, Geneva, Switzerland

The LHC collimators are exposed to very high levels of radiation, which means that the power drivers must be installed far from the stepping motors that they drive. Due to the geometry of the underground installations, the distances can be up to 1 km. The long cables that connect the drivers to the motors behave as transmission lines modifying dramatically the impedance seen by the drivers and consequently jeopardizing the control performance of Pulse Width Modulation (PWM) drivers. In this paper we address this problem, provide an analytical model of the driver-cable-motor system and describe the analog solution we have developed to improve the performance of a typical off the shelf driver. Finally we characterize the improvement of the performances with measurements of positioning repeatability and show that electromagnetic emissions from the long cables are drastically reduced, making the use of stepping motors compatible with extremely sensitive instrumentation such as the LHC Beam Loss Monitors (BLM).

TUPS050

Target Optimisation Studies for MuSR Applications

target, proton, simulation, neutron

1641

A. Bungau, C. Bungau, R. Cywinski
University of Huddersfield, Huddersfield, United Kingdom
P.J.C. King, J.S. Lord
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom

Considering the ISIS muon target as a reference, Geant4 simulations have been performed to optimise the target parameters with respect to muon and pion yield. Previous studies suggested that the muon production can be optimised by using a thin graphite slab target with an incident proton energy significantly lower than initially considered. The current paper discusses a possible target design fully optimised for MuSR studies.

TUPS084

Development Status of PPS, MPS and TS for IFMIF/EVEDA Prototype Accelerator

controls, radiation, status, monitoring

1734

H. Takahashi, T. Kojima, T. Narita, K. Nishiyama, H. Sakaki, K. Tsutsumi
JAEA, Aomori, Japan

Control System for IFMIF/EVEDA* prototype accelerator consists of six subsystems; Central Control System (CCS), Local Area Network (LAN), Personnel Protection System (PPS), Machine Protection System (MPS), Timing System (TS) and Local Control System (LCS). The IFMIF/EVEDA prototype accelerator provides deuteron beam with the power more than 1 MW, which is as same as that in cases of J-PARC and SNS. Then, the PPS is required to protect technical and engineering staff against unnecessary exposure and the other danger phenomena. The MPS and the TS are strongly required a high performance and precision to avoid radio-activation of the accelerator components. To realize these requirements, the PPS designed that Programmable Logic Controllers (PLCs) are used mainly, and a sequence is programmed for entering and leaving of controlled area and etc. Hardware and logic sequences for the MPS are designed to realize the beam inhibition time within 30 micro-seconds. The TS prototype modules were designed and tested using 10 MHz master clock and 100 Hz reference trigger. This article presents the PPS, MPS and TS design in details.
* International Fusion Material Irradiation Facility / Engineering Validation and Engineering Design Activity

TUPZ006

Aperture Determination in the LHC Based on an Emittance Blowup Technique with Collimator Position Scan

emittance, injection, optics, storage-ring

1810

R.W. Assmann, R. Bruce, M. Giovannozzi, G.J. Müller, S. Redaelli, F. Schmidt, R. Tomás, J. Wenninger, D. Wollmann
CERN, Geneva, Switzerland
M. Alabau
IFIC, Valencia, Spain

A new method to determine the LHC aperture was proposed. The new component is a collimator scan technique that refers the globally measured aperture limit to the shadow of the primary collimator, expressed in σs of rms beam size. As a by-product the BLM response to beam loss is quantified. The method is described and LHC measurement results are presented.

TUPZ012

Machine-induced Showers entering the ATLAS and CMS Detectors in the LHC

simulation, proton, background, collimation

1825

R. Bruce, R.W. Assmann, V. Boccone, H. Burkhardt, F. Cerutti, A. Ferrari, M. Huhtinen, W. Kozanecki, Y.I. Levinsen, A. Mereghetti, A. Rossi, Th. Weiler
CERN, Geneva, Switzerland
N.V. Mokhov
Fermilab, Batavia, USA

One source of experimental background in the LHC is showers induced by particles hitting the upstream collimators or particles that have been scattered on the residual gas. We estimate the flux and distribution of particles entering the ATLAS and CMS detectors through FLUKA simulations originating from tertiary collimator hits and inelastic beam-gas interactions. Comparisons to MARS results are also presented.

TUPZ015

Electron Cloud Parameterization Studies in the LHC

electron, vacuum, simulation, emittance

1834

C.O. Domínguez, G. Arduini, V. Baglin, G. Bregliozzi, J.M. Jimenez, E. Métral, G. Rumolo, D. Schulte, F. Zimmermann
CERN, Geneva, Switzerland

During LHC beam commissioning with 150, 75 and 50-ns bunch spacing, important electron-cloud effects, like pressure rise, cryogenic heat load, beam instabilities or emittance growth, were observed. The main strategy to combat the LHC electron cloud relies on the surface conditioning arising from the chamber-surface bombardment with cloud electrons. In a standard model, the conditioning state of the beam-pipe surface is characterized by three parameters: 1. the secondary emission yield; 2. the incident electron energy at which the yield is maximum; and 3. the probability of elastic reflection of low-energy primary electrons hitting the chamber wall. Since at the LHC no in-situ secondary-yield measurements are available, we compare the relative local pressure-rise measurements taken for different beam configurations against simulations in which surface parameters are scanned. This benchmark of measurements and these simulations is used to infer the secondary-emission properties of the beam-pipe at different locations around the ring and at various stages of the surface conditioning. In this paper we present the methodology and first results from applying the technique to the LHC.

TUPZ025

Experience with Offset Collisions in the LHC

luminosity, target, emittance, controls

1858

G. Papotti, R. Alemany-Fernandez, F. Follin, R. Giachino, W. Herr, T. Pieloni, M. Schaumann
CERN, Geneva, Switzerland
R. Calaga, R. Miyamoto
BNL, Upton, Long Island, New York, USA

To keep the luminosity under control, some experiments require the adjustment of the luminosity during a fill, so-called luminosity leveling. One option is the separate the beams transversely and adjust the separation to the desired collision rate. The results from controlled experiments are reported and interpreted. The feasibility of this method for ultimate luminosities is discussed.

TUPZ028

Beam Based Optimization of the Squeeze at the LHC

feedback, optics, simulation, controls

1867

X. Buffat
EPFL, Lausanne, Switzerland
M. Lamont, S. Redaelli, J. Wenninger
CERN, Geneva, Switzerland

The betatron squeeze is a critical operational phase for the LHC because it is carried out at top energy, with the maximum stored energy and with reduced aperture margins in the superconducting triplets. A stable operation with minimum beam losses must be achieved in order to ensure a safe and efficient operation. The operational experience at the LHC showed that this is possible. The operation in 2010 is reviewed. In particular, orbit, tune and chromaticity measurements are investigated and correlated to beam losses. Different optimizations are then proposed towards a more efficient and robust operation. The improvements obtained for the operation in 2011 are presented.

TUPZ037

Momentum Aperture for the Low Beta* Lattices in RHIC Au-Au Runs

lattice, dynamic-aperture, heavy-ion, ion

1891

Y. Luo, K.A. Brown, W. Fischer, X. Gu, G. Robert-Demolaize, T. Roser, V. Schoefer, S. Tepikian, D. Trbojevic
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In this article we calculate the momentum apertures with the low beta* lattices of 100 GeV RHIC Au-Au run. With RF re-bucketing, the maximum off-momentum spread reaches 1.7 ·10^-03 at store. To improve the momentum aperture, we need to reduce the nonlinear chromaticities. The methods to correct second order chromaticities in RHIC rings are presented. We also scan beta* at IP6 and IP8 and working point. The challenges to further reduce beta* in the RHIC Au-Au operation are discussed.

WEPC015

Tuning Methods for HIMAC Multiple-energy Operation

betatron, acceleration, resonance, synchrotron

2037

K. Katagiri, T. Furukawa, Y. Iwata, K. Noda, S. Sato, T. Shirai
NIRS, Chiba-shi, Japan
K. Mizushima
Chiba University, Graduate School of Science and Technology, Chiba, Japan
E. Takeshita
Gunma University, Heavy-Ion Medical Research Center, Maebashi-Gunma, Japan

Beam stability of multiple-energy operation at HIMAC synchrotron was improved for the fast raster-scanning irradiation. In order to improve the transverse stability, the working point of the betatron tune was investigated during one operation cycle. The signals were collected from the beam position monitor using a fast data-acquisition unit. The temporal evolution of the horizontal and vertical betatron tune was evaluated by using the short time Fourier transform. Analyzed results showed that variation of the betatron tune in the acceleration interval passed through the 3rd-order coupling resonance line, and it caused undesirable emittance growth. In order to keep the working point within the desirable operating region, the current pattern of the power supplies for the quadrupole magnets was corrected by using the variation of the betatron tune. The experimental results showed that the working point could be successfully stabilized, and the undesirable beam losses could be reduced during the acceleration interval.

WEPC021

Optical Design of the Proton Beam Lines for the Neutron Research Complex INR RAS and Medical Application

proton, neutron, target, linac

2049

M.I. Grachev, E.V. Ponomareva
RAS/INR, Moscow, Russia

The optical design for the layout of the beam lines for the neutron research complex INR RAS and medical application on the basis of the Linear accelerator are presented here. The proposed schemes have been realized at the INR RAS. The necessary size and shape of the proton beam at the location of the neutron target are obtained. Methods and results for the tuning of the high current beams are presented in this paper.

WEPC054

Amplitude Dependent Tune Spread in the CR Operated as an Antiproton Collector

sextupole, quadrupole, antiproton, simulation

2136

A. Dolinskii, C. Dimopoulou, O.E. Gorda, S.A. Litvinov, F. Nolden, M. Steck
GSI, Darmstadt, Germany

The Collector Ring is planned to be built for efficient cooling of antiprotons and rare isotopes beams. In order to accept hot antiproton beams coming from a separator large aperture magnets are required. This paper examines the effects which, may influence on the beam dynamic because of both large both betatron amplitude oscillations (240 mm mrad) and momentum spread (6%). Using analytic expressions the amplitude-dependent tune shifts driven by sextupole magnets, fringe field of quadrupole magnets and kinematics effects have been calculated. The results are compared with numerical simulations. Tracking studies for the CR operated as an antiproton collector have been performed considering the real shape of the magnetic field of the wide aperture quadrupole. We report on quantitative studies of the effects on the tune spread and its influence on the beam losses.

WEPC057

Estimation of the Dynamic Aperture by Transverse Beam Excitation with Noise Close to a Resonance

dynamic-aperture, lattice, resonance, sextupole

2145

S. Sorge, G. Franchetti
GSI, Darmstadt, Germany

The present heavy ion synchrotron SIS-18 will be upgraded to be used as a booster for further synchrotrons being part of the FAIR project underway at GSI. Recently, a method was developed to measure the physical aperture of SIS-18 using transverse RF noise. This method is based on the transverse expansion of the beam with noise beyond the limiting aperture generating beam loss. The aperture was determined from the comparison of the resulting time evolution of the beam current in the machine with that obtained from a numerical simulation. In this study we attempt to apply this method to determine the dynamic aperture of SIS-18.

WEPC164

First Operation of a Fiber Beam Loss Monitor at the SACLA FEL

undulator, vacuum, electron, radiation

2367

X.-M. Maréchal, T. Itoga
JASRI/SPring-8, Sayo-gun, Japan
Y. Asano
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

A fiber-based Cerenkov beam loss monitor (CBLM) has been developed as a quick and long-range detection tool for radiation safety at the X-ray FEL SACLA (SPring-8 angstrom compact free electron laser) to minimize electron beam losses. Based on tests carried out at the 250 MeV SPring-8 Compact SASE Source facility, large core (400 μm), long (>120 m) multimode fibers were selected and installed in the undulator section of SACLA. We report on the first few months of operation of the CBLM. During the commissioning of the X-FEL, the CBLM has performed effectively, with a detection limit below 10 pC per pulse across the 110 meters of the in-vacuum undulators, and with a position accuracy of less than 2 m. Experimental results are presented along with detailed numerical studies including the geometry of in-vacuum insertion devices, and discussed.

WEPC165

Monte Carlo Simulation of the Total Dose Distribution around the 12 MeV UPC Race-track Microtron and Radiation Shielding Calculations

shielding, radiation, simulation, target

2370

C. de la Fuente, M.A. Duch, Yu.A. Kubyshin
UPC, Barcelona, Spain
V.I. Shvedunov
MSU, Moscow, Russia

The Technical University of Catalonia is building a miniature 12 MeV electron race-track microtron for medical applications. In the paper we study the leakage radiation caused by beam losses inside the accelerator head, as well as the bremstrahlung radiation produced by the primary beam in the commissioning setting. Results of Monte Carlo simulations using the PENELOPE code are presented and two shielding schemes, global and local, are studied. The obtained shielding parameters are compared with estimates based on international recommendations of the radiation safety standards.

WEPC166

Licensing and Safety Issues of the ESS Accelerator

shielding, radiation, target, neutron

2373

P.E.T. Jacobsson, M. Brandin, D. Ene, T. Hansson
ESS, Lund, Sweden

The licensing process for the European Spallation Source (ESS) has started up. The process includes both an application to the Environmental Court in Sweden as well as the application towards the Swedish Radiation Protection Authority (SSM). The applications will be based on an Environmental Impact Assessment EIA) and a Safety Analysis Report (SAR). One important step has been to define which regulations that apply for ESS. ESS has also set up General Safety Objectives (GSO). Based on the GSO and the legal requirements, the process design of the whole ESS facility is ongoing. This paper will focus upon the radiation safety issues related to the accelerator. This includes items as radiation shielding, personal protection system and operation emissions. Analyses and calculations, based on a preliminary design and layout of the ESS accelerator, will be presented. Discussion is made on issues like shielding material, shielding design and analysis models.

WEPC170

Handling of BLM Abort Thresholds in the LHC

monitoring, injection, quadrupole, proton

2382

E. Nebot Del Busto, B. Dehning, E.B. Holzer, S. Jackson, G. Kruk, M. Nemcic, A. Nordt, A. Orecka, C. Roderick, M. Sapinski, A. Skaugen, C. Zamantzas
CERN, Geneva, Switzerland

The Beam Loss Monitoring system (BLM) for the LHC consists of about 3600 Ionization Chambers located around the ring. Its main purpose is to request a beam abort when the measured losses exceed a certain threshold. The BLM detectors integrate the measured signals in 12 different time intervals (running from 40 us to 83.8 s) enabling for a different set of abort thresholds depending on the duration of the beam loss. Furthermore, 32 energy levels running from 0 to 7 TeV account for the fact that the energy density of a particle shower increases with the energy of the primary particle, i.e. the beam energy. Thus, about 1.3·10⁶ thresholds must be handled and send to the appropriate processing modules for the system to function. These thresholds are highly critical for the safety of the machine and depend to a large part on human judgment, which cannot be replaced by automatic test procedures. The BLM team has defined well established procedures to compute, set and check new BLM thresholds, in order to avoid and/or find non-conformities due to manipulation. These procedures, as well as the tools developed to automate this process are described in detail in this document.

WEPC171

Requirements of a Beam Loss Monitoring System for the CLIC Two Beam Modules

photon, linac, simulation, monitoring

2385

S. Mallows
The University of Liverpool, Liverpool, United Kingdom
E.B. Holzer, A.P. Mechev, J.W. van Hoorne
CERN, Geneva, Switzerland
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

he Compact Linear Collider (CLIC) study investigates the feasibility of a high-energy electron-positron linear collider optimized for a centre of mass energy of 3 TeV. To achieve the high accelerating gradients, the RF power is produced by a novel two-beam acceleration method in which a decelerating drive beam supplies energy to the main accelerating beam. The linacs are arranged in modular structures referred to as the two beam modules which cover 42 km of beamline. Beam losses from either beam can have severe consequences due to the high intensity drive beam and the high energy, small emittance main beam. This paper presents recent developments towards the design of a Cherenkov fiber BLM system and discusses its ability to distinguish losses originating from either beam.

WEPC172

Beam-induced Quench Test of a LHC Main Quadrupole

simulation, proton, quadrupole, monitoring

2388

A. Priebe, K. Dahlerup-Petersen, B. Dehning, E. Effinger, J. Emery, E.B. Holzer, C. Kurfuerst, E. Nebot Del Busto, A. Nordt, M. Sapinski, J. Steckert, A.P. Verweij, C. Zamantzas
CERN, Geneva, Switzerland
A. Priebe
EPFL, Lausanne, Switzerland

Unexpected beam loss might lead to transition of a superconducting accelerator magnet to a normal conducting state. The LHC beam loss monitoring (BLM) system is designed to abort the beam before the energy deposited in the magnet coils reaches a quench-provoking level. In order to verify the threshold settings generated by simulation, a series of beam-induced quench tests at various beam energies have been performed. The beam losses are generated by means of an orbit bump peaked in one of the main quadrupole magnets. The analysis not only includes BLM data but also data from the electrical quench protection and cryogenic systems. The measurements are compared to Geant4 simulations of energy deposition inside the coils and corresponding BLM signal outside the cryostat. The results are also extrapolated to higher beam energies.

WEPC173

LHC Magnet Quench Test with Beam Loss Generated by Wire Scan

proton, simulation, electron, quadrupole

2391

M. Sapinski, F. Cerutti, K. Dahlerup-Petersen, B. Dehning, J. Emery, A. Ferrari, A. Guerrero, E.B. Holzer, M. Koujili, A. Lechner, E. Nebot Del Busto, M. Scheubel, J. Steckert, A.P. Verweij, J. Wenninger
CERN, Geneva, Switzerland

Beam losses with millisecond duration have been observed in the LHC in 2010 and 2011. They are expected to be provoked by dust particles falling into the beam. These losses could compromise the LHC availability if they provoke quenches of superconducting magnets. In order to investigate the quench limits for this loss mechanism, a quench test using the wire scanner has been performed, with the wire movement through the beam mimicking a loss with similar spatial and temporal distribution as in the case of dust particles. This paper will show the conclusions reached for millisecond-duration dust-provoked quench limits. It will include details on the maximum energy deposited in the coil as estimated using FLUKA code, showing good agreement with quench limit estimated from the heat transfer code QP3. In addition, information on the damage limit for carbon wires in proton beams will be presented, following electron microscope analysis which revealed strong wire sublimation.

WEPC174

A Failure Catalogue for the LHC

monitoring, extraction, vacuum, injection

2394

S. Wagner, R. Schmidt, B. Todd, J.A. Uythoven, M. Zerlauth
CERN, Geneva, Switzerland

The LHC, with a stored energy of more than 360 MJ per beam, requires a complex machine protection system to prevent equipment damage. The system was designed based on a large number of possible failures in the subsystems and operational phases of the LHC. This led to a mixed system with active and passive protection. The active part monitors many thousand parameters (such as beam losses, temperatures in superconducting magnets, power converter currents, etc.) and triggers a beam dump in case a failure is detected. The passive part includes protection elements like collimators and beam absorbers to ensure the prevention of damage in case of single turn beam losses (e.g. during beam transfer and injection). So far, the knowledge of the possible failures is distributed over the different teams involved in the design, construction and operation of the LHC. A newly started project aims at bringing together this knowledge in a common failure catalogue. The chosen approach in addition is expected to allow for the identification of failures that might not have been considered yet or that require further measures. This paper introduces the approach and presents the first experience.

WEPC176

Beam Loss Monitoring and Machine Protection System Design and Application for the ALICE Test Accelerator at Daresbury Laboratory

monitoring, radiation, dipole, simulation

2400

S.R. Buckley, J.-L. Fernández-Hernando
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

ALICE is a demonstrator accelerator system which has been designed and built at Daresbury Laboratory. The heart of this facility is an ERL accelerator and a powerful multi-terrawatt laser. It serves as an advanced test facility for novel accelerator and photon science applications. Beam loss monitoring and machine protection systems are vital areas for the successful operation of ALICE. These systems are required, both for efficient machine set up and for hardware protection during operation. This paper gives an overview of the system design, commissioning details and a summary of the systems’ effectiveness as a diagnostic tool.

WEPO006

Suppression of Leakage Fields from DC Magnets in J-PARC 3 GeV RCS

shielding, extraction, septum, vacuum

2412

M. Yoshimoto, H. Harada, N. Hayashi, H. Hotchi, M. Kinsho, P.K. Saha, K. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

In the J-PARC 3 GeV RCS, we found that DC leakage fields from the extraction beam line significantly affected the beam. For this issue, we installed additional shields and got the 40% reduction of the DC leakage field. Thus the circulating beam loss was successfully reduced. In this presentation, we report the detail of the shield structure and the results of the beam studies.

WEPS003

SIS18 – Intensity Record with Intermediate Charge State Heavy Ions

ion, heavy-ion, injection, acceleration

2484

P.J. Spiller
GSI, Darmstadt, Germany
L.H.J. Bozyk
FIAS, Frankfurt am Main, Germany
P. Puppel
HIC for FAIR, Frankfurt am Main, Germany

Funding: Project partly funded by the European Community DIRAC-PHASE-1 / Contract number: 515876
In order to reach the desired intensities of heavy ion beams for the experiments at FAIR, SIS18 and SIS100 have to be operated with intermediate charge states. Operation with intermediate charge state heavy ions at the intensity level of about 10¹¹ ions per cycle has never been demonstrated elsewhere and requires a dedicated upgrade program for SIS18 and a dedicated machine design for SIS100. The specific problems coming along with the intermediate charge state operation in terms of charge exchange processes at collisions with residual gas atoms, pressure bumps by ion induced desorption and corresponding beam loss appears far below the typical space charge limits. Thus, new design concepts and new technical equipment addressing these issues are developed and realized with highest priority. The upgrade program of SIS18 addressing the goal of minimum ionization beam loss and stable residual gas pressure conditions has been defined in 2005. A major part of this upgrade program has been successfully realized, with the result of a world record in accelerated number of intermediate charge state heavy ions.

WEPS008

Operation Status and Future Plan of J-PARC Main Ring

extraction, kicker, linac, betatron

2499

T. Koseki
KEK, Ibaraki, Japan

The J-PARC Main Ring (MR) has started users operation since 2009. The MR has two beam extraction systems. One is a fast extraction (FX) system for beam delivery to the neutrino beam line of the Tokai-to-Kamioka (T2K) experiment, and the other is a slow extraction (SX) system for beam delivery to the hadron experimental hall. For the T2K experiment, the maximum beam power of 145 kW is delivered continuously. For users of the hadron experimental hall, the beam power of 3 kW is delivered with extraction efficiency of 99.5%. In this paper, status of the high power beam operation of the MR is presented. Future prospect for increasing beam intensity is also discussed.

WEPS046

Longitudinal Beam Acceptance of J-PARC Drift Tube Linac

DTL, linac, simulation, cavity

2592

T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan
M. Ikegami
KEK, Ibaraki, Japan
A. Miura, G.H. Wei
JAEA/J-PARC, Tokai-mura, Japan
H. Sako
JAEA, Ibaraki-ken, Japan

The longitudinal acceptance of the J-PARC Drift Tube Linac (DTL) was measured by synchronous phase scan method. The IMPACT simulation indicated DTL longitudinal acceptance is shrinked if the DTL tank level reduced, but beam energy finally acheved at the Linac is almost same as the case of nominal tank level. We measured the acceptance and confirmed the simulation is correct.

WEPS047

Beamloss Study at J-PARC Linac by using Geant4 Simulation

simulation, scattering, linac, radiation

2595

T. Maruta
JAEA/J-PARC, Tokai-mura, Japan

Beamloss is one of the key issue for intense hadron beam accelerators. Most of case, origin of beamloss is scattering process between beam particle and residual gas inside vacuum duct. In the case of J-PARC Linac, H⁻ ions emitted from an Ion source are accelerated up to 181 MeV, then the beam is transported to RCS. The H⁻ ion is the system comprised from a proton and two electrons. If the H⁻ ion is scattered with residual gas, these one or two electrons are escaped, then H⁻ becomes H0 or H⁺(proton). H0 or H⁺ is uncontrollable and finally it goes to beam duct. This process is based on physics process, and Geant4 is matched to this kind of simulation study. I programmed SDTL (50 MeV) to L3BT (181 MeV) section at J-PARC Linac by using Geant4 code. I also wrote H⁻ and H0 library which makes it possible for Geant4 to simulate them. I will show the simulation results.

WEPS048

Dependence of Beam Loss on Vacuum Pressure Level in J-PARC Linac

vacuum, linac, ion, collimation

2598

G.H. Wei
KEK/JAEA, Ibaraki-Ken, Japan
K. Hirano, T. Maruta, A. Miura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
K. Ikegami
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

In J-PARC linac, a 181-MeV negative hydrogen beam is supported to a succeeding 3-GeV synchrotron with normal operation power at 100-300 kW. During operation, a beam loss in the straight section of the beam transport line immediately after the linac exit is found. The residual radiation level reaches 0.3 mSv/h on the surface of the vacuum chamber several hours after the beam shutdown with the linac beam power of 12 kW. We suppose that the residual gas scattering of negative hydrogen ions generates neutral hydrogen atoms and they give rise to the beam loss by hitting the vacuum chamber wall. To confirm this speculation, the vacuum pressure level in the linac had been changed in order to find the dependence of the beam loss on it. After data analysis, we found the relationship between beam loss amplitude, which was attained from beam loss signal, and vacuum pressure was linear. Corresponding deduction and simulation has been down according to the residual gas components in linac chamber. In this paper, we present the experimental result and some simulations in this study.

WEPS071

High Power, High Energy Cyclotrons for Muon Antineutrino Production: the DAEdALUS Project

proton, cyclotron, target, extraction

2667

J.R. Alonso, T. Smidt
MIT, Cambridge, Massachusetts, USA

Neutrino physics is very much at the forefront of today's research. Large detectors installed in deep underground locations study neutrino masses, CP violation, and oscillations using neutrino-sources including long- and short-baseline beams of neutrinos from muons decaying in flight. DAEdALUS* looks at neutrinos from stopped muons, “Decay At Rest (DAR)” neutrinos. The DAR neutrino spectrum has no electron antineutrinos (nu-e-bar) (pi-minus are absorbed), so a detector with much hydrogen (water-Cherenkov or liquid scintillator) is sensitive to appearance of nu-e-bar’s oscillating from nu-mu-bar via inverse-beta-decay. Oscillations are studied using shorter baselines, less than 20 km reaching the same range as the current and planned high-energy neutrino lines at Fermilab. As the neutrino flux is not variable, nor is the energy, the baseline is varied, plans call for 3 accelerator-based neutrino sources at 1.5, 8 and 20 km with staggered beam-on cycles. Key is cost-effectively generating megawatt beams of 800 MeV protons. A superconducting ring cyclotron is being designed by L. Calabretta and his group**. This revolutionary design could find application in many ADS-related fields.
* DAEdALUS Expression of Interest, arXiv:10⁰⁶.0260
** Calabretta et al., "A Superconducting Ring Cyclotron to Search for CP Violation in the Neutrino Sector", this conference

WEPS094

Dynamic Vacuum Stability in SIS100

ion, vacuum, extraction, cryogenics

2724

P. Puppel, U. Ratzinger
IAP, Frankfurt am Main, Germany
P.J. Spiller
GSI, Darmstadt, Germany

SIS100 is the main synchrotron of the FAIR project. It is designed to accelerate high intensity intermediate charge state uranium beams from 200 MeV/u up to 2.7 GeV/u. Intermediate charge state heavy ions are exposed to a high probability of charge exchange due to collisions with residual gas molecules. Since the charge exchange process changes the magnetic rigidity, the involved ions are lost behind dispersive elements, and an energy-dependent gas desorption takes place. The StrahlSim code has been used to predict the stability of the residual gas pressure in SIS100 under beam loss driven dynamic conditions. The results show, that a stable operation at highest U²⁸⁺ intensities is possible, under the constraint that the vacuum chambers of the ion catcher system are cold enough to pump hydrogen. Furthermore, in order to determine the load to the cryogenic system, the average beam energy deposition onto the ion catcher system has been calculated.

WEPS096

Injection Energy Recovery of J-PARC RCS

power-supply, injection, impedance, septum

2730

N. Hayashi, H. Hotchi, J. Kamiya, P.K. Saha, T. Takayanagi, K. Yamamoto, M. Yamamoto, Y. Yamazaki
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

The J-PARC RCS is a high beam power Rapid-Cycling Synchrotron (RCS). The original designed injection energy is 400MeV, although presently it is 181MeV, and its beam power is limited to 0.6MW. Works to recover the Linac energy are ongoing and injection magnets power supplies upgrade are required in the RCS. In order to achieve 1MW designed beam power, new instrumentation is also planned simultaneously. Activities related injection energy recovery in the J-PARC RCS is presented.

WEPS097

Performance of Multi-harmonic RF Feedforward System for Beam Loading Compensation in the J-PARC RCS

cavity, impedance, beam-loading, acceleration

2733

F. Tamura, M. Nomura, A. Schnase, T. Shimada, M. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
K. Hara, C. Ohmori, M. Toda, M. Yoshii
KEK/JAEA, Ibaraki-Ken, Japan
K. Hasegawa
KEK, Tokai, Ibaraki, Japan

The beam loading compensation is a key part for acceleration of high intensity proton beams in the J-PARC RCS. In the wide-band MA-loaded RF cavity, the wake voltage consists of not only the accelerating harmonic component but also the higher harmonics. The higher harmonic components cause the RF bucket distortion. We employ the RF feedforward method to compensate the multi-harmonic beam loading. The full-digital feedforward system is developed, which compensates the first three harmonic components of the beam loading. We present the results of the beam test with a high intensity proton beam (2.5·10¹³ ppp). The impedance seen by the beam is greatly reduced, the impedance of the fundamental accelerating harmonic is reduced to less than 25 ohms in a full accelerating cycle, while the shunt resistance of the cavity is in the order of 800 ohms. The performance of the feedforward system is promising for achievement of the design beam power, 1 MW, in the future.

THOAA03

Overview of LHC Beam Loss Measurements

luminosity, quadrupole, proton, collimation

2854

B. Dehning, A.E. Dabrowski, M. Dabrowski, E. Effinger, J. Emery, E. Fadakis, V. Grishin, E.B. Holzer, S. Jackson, G. Kruk, C. Kurfuerst, A. Marsili, M. Misiowiec, E. Nebot Del Busto, A. Nordt, A. Priebe, C. Roderick, M. Sapinski, C. Zamantzas
CERN, Geneva, Switzerland
E. Griesmayer
CIVIDEC Instrumentation, Wien, Austria

The LHC beam loss monitoring system based on ionization chambers is used for machine protection, quench prevention and accelerator optimization. After one full year of operation it can be stated that its main functionality, that of the protection of equipment, has proven to be very robust with no issues observed for hundreds of critical beam loss events and the number of false beam aborts well below expectation. In addition the injection, dump and collimation system make regular use of the published loss measurements for system analysis and optimisation, such as the determination of collimation efficiency in order to identify possible intensity limitations as early as possible. Intentional magnet quenches have been performed to verify both the calibration accuracy of the system and the accuracy of the loss pattern predictions from simulations. Tests have also been performed with fast loss detectors based on single- and polycrystalline CVD diamond, which are capable of providing nanosecond resolution time loss structure. This presentation will cover all of these aspects and give an outlook on future performance.

Slides THOAA03 [1.972 MB]

THOBB03

Research and Development of Novel Advanced Materials for Next-generation Collimators

impedance, radiation, target, collimation

2888

A. Bertarelli, G. Arnau-Izquierdo, F. Carra, A. Dallocchio, M. Gil Costa, N. Mariani
CERN, Geneva, Switzerland

Funding: This work has partly been carried out through the European Coordination for Accelerator Research and Development (EuCARD), co-sponsored by EU 7th Framework Program.
The study of innovative collimators is essential to handle the high energy particle beams required to explore unknown territory in basic research. This calls for the development of novel advanced materials, as no existing metal-based or carbon-based material possesses the combination of physical, thermal, electrical and mechanical properties, imposed by collimator extreme working conditions. A new family of materials, with promising features, has been identified: metal-diamond composites. These materials are to combine the outstanding thermal and physical properties of diamond with the electrical and mechanical properties of metals. The best candidates are Copper-Diamond (Cu-CD) and Molybdenum-Diamond (Mo-CD). In particular, Mo-CD may provide interesting properties as to mechanical strength, melting temperature, thermal shock resistance and, thanks to its balanced material density, energy absorption. The research program carried out on these materials at CERN and collaborating partners is presented, mainly focusing on the theoretical investigation, material characterization, and manufacturing processes.

Slides THOBB03 [3.948 MB]

THPC006

Experiments to Measure Electron Beam Energy using Spin Depolarization Method on SOLEIL Storage Ring

polarization, storage-ring, electron, synchrotron

2915

J.F. Zhang, L. Cassinari, M. Labat, A. Nadji, L.S. Nadolski, D. Pédeau
SOLEIL, Gif-sur-Yvette, France

The electron beam energy on SOLEIL storage ring was successfully measured using spin depolarization method after several attempts over the past few years. The experimental results demonstrate that the effective polarization was 91.3%±3% and polarization time was 17±2.3 minutes as expected from the simulation using SLIM code. The beam was depolarized using an AC shaker and the depolarization was monitored using DCCT and beam loss monitors. The beam energy was measured with accuracy up to a few 10^-5.

THPC070

An Automated Statistical Analysis Package for the Study of Synchrotron Light Source Operation

cavity, storage-ring, monitoring, synchrotron

3056

C. Christou, C.P. Bailey, V.C. Kempson, V.J. Winter
Diamond, Oxfordshire, United Kingdom

Machine faults and interruptions to user beam at Diamond Light Source are recorded in a Fault Log Database (FLDB) running under Microsoft Access. The scope of numerical analysis in Access is limited, and so an advanced data analysis package has been written in Matlab to exploit the powerful numeric functions available in this environment to automatically analyze machine faults and summarize data for reliability reports. Figures of merit such as mean time between failure (MTBF), mean time to repair (MTTR), total up time and total number of faults over the machine as a whole and by technical group can be calculated, and more advanced Pareto and Weibull analyses can be instantly generated. Data is presented for Diamond Light Source both for the latest year of operation and since user beam began in 2007, and the impact of different technical groups, in particular the storage ring RF, is considered. Failure distributions and the underlying hazard functions are produced and compared with statistical models to highlight deviations from randomly occurring events and to quantify changes in failure probability with time.

THPS035

Collimator Upgrade Plan of the J-PARC Main Ring

radiation, injection, collimation, septum

3496

M.J. Shirakata, K. Ishii, C. Kubota, T. Oogoe, J. Takano
KEK, Ibaraki, Japan
Y. Kuniyasu
MELCO SC, Tsukuba, Japan
Y. Takiyama
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

A halo collimation system is prepared in the middle of injection-straight section in order to localize the beam loss occurred in main ring. It consists of three collimator units. The first unit scatters halo components, and the other two units work as halo catchers. The permitted amount of beam losses in the collimator section is designed to be 450 W at the present. The upgrade plan of halo collimation system is running in order to achieve about ten times larger beam loss capability for high-power beam operation. The collimator upgrade is planned by installing a new collimator set and radiation shields which cover the collimator section. New collimator units are designed to be able to line-out the jaw with a part of radiation shield including the mechanical devices. The design work of collimator units and radiation shields is presented in this report.

THPS040

Measurement of the Stripping Efficiency for HBC Stripper Foil in the 3-GeV RCS of J-PARC

injection, extraction, proton, scattering

3511

P.K. Saha, H. Harada, S. Hatakeyama, H. Hotchi, M. Kinsho, Y. Yamazaki, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Y. Irie, I. Sugai
KEK, Ibaraki, Japan

We have carried out experimental measurement of the stripping efficiency for the newly developed HBC (Hybrid type Boron doped Carbon) stripper foils. The HBC foil is used for charge-exchange injection in the RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex) and plays an important role for the RCS operation. We have developed a rather simple but very precise method using which stripping efficiencies for several HBC foils were determined accurately. Importance of knowing an accurate stripping efficiency so as to determine a realistic stripper foil for the RCS operation will be discussed.

THPS042

Feasibility Studies of the Foil Scattering Extraction in CSNS/RCS

extraction, scattering, simulation, proton

3517

N. Wang, M.Y. Huang, N. Huang, S. Wang
IHEP Beijing, Beijing, People's Republic of China

A slow extraction based on foil scattering was suggested in the rapid cycling synchrotron of China Spallation Neutron Source for particle calibration. Protons with large scattering angle will be extracted during 2 ms at the end of each beam cycle, via a carbon foil. The feasibility of the extraction scheme is investigated. The extraction efficiency is studied by both single turn and multi-turn simulations with FLUKA and ORBIT, respectively. Beam losses due to multiple scattering to the downstream components are predicted.

THPS053

Results from the HiRadMat Primary Beam Line Commissioning

optics, proton, controls, instrumentation

3547

C. Heßler, M. Arruat, J. Bauche, K. Bestmann, J. Blanco, N. Conan, K. Cornelis, I. Efthymiopoulos, H. Gaillard, B. Goddard, D. Grenier, G.G. Gros, A. Habert, L.K. Jensen, V. Kain, G. Le Godec, M. Meddahi, S. Pelletier, P. Pepinster, B. Puccio, C. Theis, P. Trilhe, G. Vandoni, J. Wenninger
CERN, Geneva, Switzerland

The High Radiation to Materials facility (HiRadMat) is a new experimental area at CERN, for studies of the impact of high-intensity pulsed beams on accelerator components and materials. The beam is delivered from the SPS by a new primary beam line, which has been constructed during the 2010/11 winter technical stop. The paper summarizes the construction phase and describes the results from the beam line commissioning in spring 2011. Beam parameter and aperture measurements are presented, as well as steering tests. A special emphasis has been put on the handling of the exceptionally flexible beam line optics in the control system.

THPS055

Controlling Beamloss at Injection into the LHC

injection, emittance, kicker, shielding

3553

B. Goddard, F. Alessio, W. Bartmann, P. Baudrenghien, V. Boccone, C. Bracco, M. Brugger, K. Cornelis, B. Dehning, A. Di Mauro, L.N. Drosdal, E.B. Holzer, W. Höfle, R. Jacobsson, V. Kain, M. Meddahi, V. Mertens, A. Nordt, J.A. Uythoven, D. Valuch, S. Weisz, E.N. del Busto
CERN, Geneva, Switzerland
R. Appleby
UMAN, Manchester, United Kingdom

Losses at injection into the superconducting LHC can adversely affect the machine performance in several important ways. The high injected beam intensity and energy mean that precautions must be taken against damage and quenches, including collimators placed close to the beam in the injection regions. Clean injection is essential, to avoid spurious signals on the sensitive beam loss monitoring system which will trigger beam dumps. In addition, the use of the two injection insertions to house downstream high energy physics experiments brings constraints on permitted beam loss levels. In this paper the sources of injection beam loss are discussed together with the contributing factors and various issues experienced in the first full year of LHC operation. Simulations are compared with measurement, and the implemented and planned mitigation measures and diagnostic improvements are described. An outlook for future LHC operation is given.

THPZ026

Collimation Dependent Beam Lifetime and Loss Rates in the LHC

collimation, luminosity, insertion, betatron

3744

D. Wollmann, R.W. Assmann, R. Bruce, F. Burkart, M. Cauchi, D. Deboy, S. Redaelli, A. Rossi, G. Valentino
CERN, Geneva, Switzerland

The four primary collimators in each LHC beam define the smallest aperture. Particles with high betatron amplitudes or momentum offset will therefore hit first a primary collimator. The instantaneous particle loss rate at primary collimators is an important measure for the global lifetime of the beams and a major ingredient to identify collimation induced performance limitations in the LHC. These loss rates have been measured during a number of LHC fills, featuring both "good" fills with high luminosity and "bad" fills with beam instabilities. The beam lifetime at the collimators was then calculated from this data for different cases. The results are presented and interpreted within this paper.

THPZ027

First Beam Results for a Collimator with In-jaw Beam Position Monitors

collimation, alignment, proton, closed-orbit

3747

D. Wollmann, O. Aberle, R.W. Assmann, A. Bertarelli, C.B. Boccard, R. Bruce, F. Burkart, M. Cauchi, A. Dallocchio, D. Deboy, M. Gasior, O.R. Jones, S. Redaelli, A. Rossi, G. Valentino
CERN, Geneva, Switzerland

With more than 100 collimators the LHC has the most complex collimation system ever installed in an accelerator. The beam-based setup time of the system was a non-negligible factor during the commissioning of the LHC. In addition if the particle orbit at a collimator goes out of tolerance, this collimator needs to be setup again. To reduce the required setup time for the collimation system and to obtain the tight tolerances required for the LHC operation with small beta* and high beam energy, a new collimator design is being developed that integrates a beam position monitor (BPM) into the jaws of the collimator. A prototype of such a phase-II LHC collimator was installed in the SPS at CERN for the 2010 run. In this paper we present the first experimental results from the beam tests performed.

THPZ029

Principles for Generation of Time-dependent Collimator Settings during the LHC Cycle

injection, optics, collimation, controls

3753

R. Bruce, R.W. Assmann, S. Redaelli
CERN, Geneva, Switzerland

The settings of the LHC collimators have to be changed during the cycle of injection, ramp and squeeze to account for variations in the orbit, beam size and normalized distance to the beam center. We discuss the principles for how the settings are calculated and show a software tool that computes them as time-dependent functions from beam-based data and theoretical optics models.

THPZ030

Halo Scrapings with Collimators in the LHC

collimation, luminosity, superconducting-magnet, proton

3756

F. Burkart, R.W. Assmann, R. Bruce, M. Cauchi, D. Deboy, S. Redaelli, A. Rossi, G. Valentino, D. Wollmann
CERN, Geneva, Switzerland
L. Lari
IFIC, Valencia, Spain

The population of the beam halo has been measured in the LHC with beam scraping experiments. Primary collimators of the LHC collimation system were used to scrape the beam halo at different statuses of the machine (injection, top energy, separated and colliding beams). In addition these measurements were used to calibrate the beam loss monitor signals to loss rates at the primary collimators. Within this paper the halo scraping method, the measured halo distribution and the calibration factors are presented and compared to theoretical predictions.

THPZ031

Acoustic Measurements in the Collimation Region of the LHC

background, radiation, collimation, proton

3759

D. Deboy, R.W. Assmann, C. Baccigalupi, F. Burkart, M. Cauchi, C.S. Derrez, J. Lendaro, A. Masi, S. Redaelli, G. Spiezia, D. Wollmann
CERN, Geneva, Switzerland

The LHC accelerator at CERN has the most advanced collimation system ever being installed. The collimators intercept unavoidable particle losses and therefore are essential to avoid beam induced quenches of the superconducting magnets. In addition, they provide passive machine protection against mis-kicked beams. During material robustness tests on a LHC collimator prototype in 2004 and 2006, vibration and acoustic measurements have shown that a beam impact detection system should be feasible using accelerometers and microphones as sensors in the LHC. Recently, such sensors have been installed close to the primary collimators in the LHC tunnel. First analyses of raw data show that the system is sensitive enough to detect beam scraping on collimators. Therefore, the implementation of a sophisticated acoustic monitoring system is under investigation. It may be useful not only to detect beam impacts on primary collimators in case of failure, but also to derive further information on beam losses that occur during regular operation. This paper gives an overview on the recent installation, results of the acoustic measurements made at the LHC, and future plans.

THPZ032

Evaluation of the Combined Betatron and Momentum Cleaning in Point 3 in Terms of Cleaning Efficiency and Energy Deposition for the LHC Collimation Upgrade

betatron, collimation, quadrupole, proton

3762

L. Lari, R.W. Assmann, V. Boccone, M. Brugger, F. Cerutti, A. Ferrari, A. Rossi, R. Versaci, V. Vlachoudis, D. Wollmann
CERN, Geneva, Switzerland
A. Faus-Golfe, L. Lari
IFIC, Valencia, Spain
A. Mereghetti
UMAN, Manchester, United Kingdom

Funding: This work has been carried out through of the European Coordination for Accelerator Research and Development (EuCARD), co-sponsored by EU 7th Framework Program.
The Phase I LHC Collimation System Upgrade could include moving part of the Betatron Cleaning from LHC Point 7 to Point 3 to improve both operation flexibility and intensity reach. In addition, the partial relocation of beam losses from the current Betatron cleaning region at Point 7 will mitigate the risks of Single Event Upsets to equipment installed in adjacent and partly not adequate shielded areas. A combined Betatron and Momentum Cleaning scenario at Point 3 implies the installation of new collimators and a new collimator aperture layout. This paper shows the whole LHC Collimator Efficiency variation with the new layout proposed at different beam energies. As part of the evaluation, energy deposition distribution in the IR3 region gives indications about the effect of this new implementation not only on the collimators themselves but also on the other beam line elements.

THPZ034

Semi-automatic Beam-based Alignment Algorithm for the LHC Collimation System

alignment, controls, collimation, feedback

3768

G. Valentino, R.W. Assmann, S. Redaelli, N.J. Sammut, D. Wollmann
CERN, Geneva, Switzerland
G. Valentino
University of Malta, Information and Communication Technology, Msida, Malta

Full beam-based alignment of the LHC collimation system was a lengthy procedure as the collimators were set up manually. A yearly alignment campaign has been sufficient for now, although in future this may lead to a decrease in the cleaning efficiency if machine parameters such as the beam orbit drift over time. Automating the collimator setup procedure can allow for more frequent alignments, therefore reducing this risk. This paper describes the design and testing of a semi-automatic algorithm as a first step towards a fully automatic setup. Its implementation in the collimator control software and future plans are described.

THPZ035

Comparison of LHC Collimation Setups with Manual and Semi-automatic Collimator Alignment

alignment, collimation, injection, insertion

3771

G. Valentino, R.W. Assmann, R. Bruce, F. Burkart, M. Cauchi, D. Deboy, S. Redaelli, A. Rossi, N.J. Sammut, D. Wollmann
CERN, Geneva, Switzerland
G. Valentino
University of Malta, Information and Communication Technology, Msida, Malta

The LHC collimation system beam-based alignment procedure has recently been upgraded to a semi-automatic process in order to increase its efficiency. In this paper, we describe the parameters used to measure the accuracy, stability and performance of the beam-based alignment of the LHC collimation system. This is followed by a comparison of the results at 450 GeV and 3.5 TeV with (1) a manual alignment and (2) with the results for semi-automatic alignment.

FRXCA01

First Years Experience of LHC Beam Instrumentation

feedback, emittance, instrumentation, luminosity

3779

O.R. Jones
CERN, Geneva, Switzerland

The LHC is equipped with a full suite of sophisticated beam instrumentation which has been essential for rapid commissioning, the safe increase in total stored beam power and the understanding of machine optics and accelerator physics phenomena. This talk will comment on all of these systems and on their contributions to the various stages of beam commissioning. It will include details on: the beam position system and its use for real-time global orbit feedback; the beam loss system and its role in machine protection; total and bunch by bunch intensity measurements; tune measurement and feedback; synchrotron light diagnostics for transverse beam size measurements, abort gap monitoring and longitudinal density measurements. Issues and problems encountered along the way will also be discussed together with the prospect for future upgrades.

Slides FRXCA01 [7.322 MB]