IPAC2012 - List of Keywords (collimation)

Paper	Title	Other Keywords	Page
MOEPPB008	Simulation of Hollow Electron Beam Collimation in the Fermilab Tevatron Collider	electron, simulation, quadrupole, collider	94
	G. Stancari, I.A. Morozov, A. Valishev Fermilab, Batavia, USA D.N. Shatilov BINP SB RAS, Novosibirsk, Russia
	Funding: Fermi Research Alliance, LLC operates Fermilab under Contract DE-AC02-07CH11359 with the US Department of Energy. This work was partially supported by the US LHC Accelerator Research Program (LARP). The concept of augmenting the conventional collimation system of high-energy storage rings with a hollow electron beam was successfully demonstrated in experiments at the Tevatron. A reliable numerical model is required for understanding particle dynamics in the presence of a hollow beam collimator. Several models were developed to describe imperfections of the electron beam profile and alignment. The features of the imperfections are estimated from electron beam profile measurements. Numerical simulations of halo removal rates are compared with experimental data taken at the Tevatron.

MOPPD072	A High Energy Collimation System for the European Spallation Source	target, beam-losses, optics, linac	529
	H.D. Thomsen, A.I.S. Holm, S.P. Møller ISA, Aarhus, Denmark
	At the European Spallation Source (ESS), a ~160 m high energy beam transport (HEBT) system is to guide the high-power (5 MW) proton beam from a superconducting 2.5 GeV linac to a spallation target station. The HEBT could include a single-pass collimation system to protect all downstream accelerator components, including the vital target. The system would be built to withstand both continuous low-power losses (i.e. introduce halo reduction) and infrequent short-term, high-power beam exposure, essentially a fault scenario. Although a collimation system could reduce the uncontrolled beam losses and thus activation levels elsewhere, it takes up precious longitudinal space intended for future beam power upgrades and sets demands for the beam optics, as will be discussed. Possible materials and specifications will also be described.

MOPPD073	Development of Transportation System for Low Energy Electron Group	electron, solenoid, simulation, injection	532
	S. Kato Tohoku University, Graduate School of Science, Sendai, Japan M. Kinsho, K. Yamamoto, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	There is a time that we want to measure the electron which occurred in the accelerator in the small situation of a noise. In that case, it is one method that we transport these electrons to the place distant form the accelerator where a noise is small. In order to realize that, development of transport line for low energy electrons is required. So, we start to develop transport line using solenoid magnets. We present status of development of this transportation system.

MOPPD074	Localization of Large Angle Foil Scattering Beam Loss Caused by Multi-Turn Charge-Exchange Injection	injection, simulation, scattering, insertion	535
	S. Kato Tohoku University, Graduate School of Science, Sendai, Japan H. Harada, S. Hatakeyama, J. Kamiya, M. Kinsho, K. Yamamoto, Y. Yamazaki, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	In the J-PARC RCS, the significant losses were observed at the branch of H⁰ dump line and the Beam Position Monitor which was put at the downstream of the H⁰ dump branch duct. These losses were caused by the large angle scattering of the injection and circulating beam at the charge exchange foil. To realize high power operation, we have to mitigate these losses. So, we started to develop a new collimation system in the H⁰ branch duct and installed in October 2011. In order to optimize this system efficiently, we primarily focused on the relative angle of collimator block from scattering particles. We simulated behavior of particles scattered by foil and produced by collimator block and researched most optimized position and angle of the collimator block. In this process, we devised the method of angular regulation of collimator block. We present the method of angular regulation and performance of this new collimation system.

MOPPD075	Optimization of the Collimation System for the CSNS/RCS	closed-orbit, beam-losses, injection, scattering	538
	N. Wang, M.Y. Huang, S. Wang, S.Y. Xu IHEP, Beijing, People's Republic of China
	Beam loss induced activation of the accelerator components is one of the primary concerns in designing a high intensity machine. The uncontrolled beam loss is required to be less than 1 W/m for hands-on maintenance of the machine. A two stage collimation system is designed in the Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS) to localize the beam losses in a restricted area. The parameters of the collimator are optimized in order to obtain high collimation efficiency. The final design of the collimation system is presented. The reliability of the collimation system is estimated for different working points and with closed orbit errors.

MOPPD076	Numerical Study of a Collimation System to Mitigate Beam Losses in the ESS Linac	linac, DTL, beam-losses, simulation	541
	R. Miyamoto, H. Danared, M. Eshraqi, A. Ponton ESS, Lund, Sweden
	The European Spallation Source (ESS) will be a 5 MW proton linac to produce spallation neutrons. A high power linac has a very low tolerance on beam losses, typically on the order of 1 W/m, to avoid activation of the linac components; hence, emittance and halo of the beam must be well controlled throughout the linac. A system of collimators in beam transport sections has been studied and tested as a means to mitigate the beam losses in several linacs. This paper presents the result of a numerical study of a collimation system for the ESS linac.

MOPPD077	Studies for an Alternative LHC Non-Linear Collimation System	proton, sextupole, betatron, impedance	544
	L. Lari, R.W. Assmann, V. Boccone, F. Cerutti, A. Mereghetti, R. Versaci, V. Vlachoudis CERN, Geneva, Switzerland A. Faus-Golfe, L. Lari, J. Resta-López IFIC, Valencia, Spain
	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. A LHC nonlinear Betatron cleaning collimation system would allow larger gap for the mechanical jaws, reducing as a consequence the collimator-induced impedance, which may limit the LHC beam intensity. In this paper, the performance of the proposed system is analyzed in terms of beam losses distribution around the LHC ring and cleaning efficiency in stable physics condition at 7TeV for Beam1. Moreover, the energy deposition distribution on the machine elements is compared to the present LHC Betatron cleaning collimation system in the Point 7 Insertion Region (IR).

MOPPD079	Preliminary Thermo-Mechanical Analysis of Angular Beam Impact on LHC Collimators	simulation, kicker, superconducting-magnet, controls	550
	M. Cauchi, R.W. Assmann, A. Bertarelli, F. Carra, A. Dallocchio, D. Deboy, N. Mariani, A. Rossi CERN, Geneva, Switzerland L. Lari IFIC, Valencia, Spain P. Mollicone UoM, Msida, Malta N.J. Sammut University of Malta, Faculty of Engineering, Msida, Malta
	Funding: This work is supported by EuCARD. 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, accident scenarios must be well studied in order to assess if the collimator design is robust against likely error scenarios. One of the catastrophic - though not very probable - accident scenarios identified is an asynchronous beam dump coupled with slight angular misalignment errors of the collimator jaw. Previous work presented a preliminary thermal evaluation of the extent of beam-induced damage for such scenarios, where it was shown that in some cases, a tilt of the jaw could actually serve to mitigate the effect of an asynchronous dump on the collimators. This paper will further analyze the response of tertiary collimators in presence of such angular jaw alignments, with the aim to identify optimal operational conditions.

MOPPD080	Improved Robustness of the LHC Collimation System by Operating with a Jaw-beam Angle	proton, radiation, scattering, alignment	553
	L. Lari, R.W. Assmann, A. Rossi CERN, Geneva, Switzerland M. Cauchi UoM, Msida, Malta A. Faus-Golfe, L. Lari IFIC, Valencia, Spain
	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 robustness of the Phase I collimation system could be improved playing with the angular orientation of each single jaw. A preliminary study on the asymmetric misalignment of the collimator jaws, scanning through different jaw angles and varying beam sizes and energy, have been carried out, aiming at minimizing the energy deposited on metallic collimators, following an asynchronous dump.

MOPPD082	Recent T980 Crystal Collimation Studies at the Tevatron Exploiting a Pixel Detector System and a Multi-strip Crystal Array	proton, collider, vacuum, scattering	559
	D.A. Still, G. Annala, R.A. Carrigan, A.I. Drozhdin, T.R. Johnson, N.V. Mokhov, V. Previtali, R.A. Rivera, V.D. Shiltsev, J.R. Zagel, V.V. Zvoda Fermilab, Batavia, USA Y.A. Chesnokov, I.A. Yazynin IHEP, Moscow Region, Russia V. Guidi, A. Mazzolari INFN-Ferrara, Ferrara, Italy Yu.M. Ivanov PNPI, Gatchina, Leningrad District, Russia D. Mirarchi, S. Redaelli CERN, Geneva, Switzerland
	Funding: Work supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy through the US LHC Accelerator Research Program (LARP). With the shutdown of the Tevatron, the T-980 crystal collimation experiment at Fermilab has been successfully completed. Results of dedicated beam studies in May 2011 are described in this paper. For these studies, two multi-strip crystals were installed in the vertical goniometer. A two-plane CMS pixel detector was positioned upstream of the E03 collimator to image beam deflected by the crystals. This new enhanced hardware yielded impressive results. For the first time, a 980-GeV proton halo beam, channeled by an O-shaped crystal of the horizontal goniometer, was imaged using the pixel detector. The performance of this crystal, the first element of the collimation system, was very good. Reproducible results on the reduction of local beam losses were also obtained with an 8-strip crystal. For volume reflection these beam losses were measured with the PIN diodes and loss monitors at the E03 collimator. The long range beam losses for the channeled beam were observed using the F17 collimator one third of the ring downstream of the crystal. The measured channeling efficiency of the O-shaped crystal and the volume reflection efficiency of the 8-strip crystal were both ~70%.

TUOAC03	Status of a Single-Aperture 11 T Nb3Sn Demonstrator Dipole for LHC Upgrades	dipole, status, magnet-design, lattice	1098
	A.V. Zlobin, N. Andreev, G. Apollinari, E.Z. Barzi, R. Bossert, G. Chlachidze, V. Kashikhin, A. Nobrega, I. Novitski, D. Turrioni, R. Yamada Fermilab, Batavia, USA B. Auchmann, M. Karppinen, L. Oberli, L. Rossi, D. Smekens CERN, Geneva, Switzerland
	Funding: Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy The planned upgrade of the LHC collimation system includes two additional collimators to be installed in the dispersion suppressor areas of points 2, 3 and 7. The necessary longitudinal space for the collimators could be provided by replacing some 8.33 T NbTi LHC main dipoles with 11 T dipoles based on Nb3Sn superconductor and compatible with the LHC lattice and main systems. To demonstrate t his possibility Fermilab and CERN have started in 2011 a joint R&D program with the goal of building by 2014 a 5.5-m long twin-aperture dipole prototype suitable for installation in the LHC. The first step of this program is the development of a 2-m long single-aperture demonstration dipole with the nominal field of 11 T at the LHC nominal current of ~11.85 kA and 60 mm bore with ~20% margin. This paper describes the design, construction and test results of the single-aperture Nb3Sn demonstrator model for the LHC collimation system upgrade.
	Slides TUOAC03 [5.812 MB]

TUPPC049	A Tapered-foil Emittance-exchange Experiment at LANSCE	emittance, proton, simulation, scattering	1278
	R.C. McCrady LANL, Los Alamos, New Mexico, USA
	We are planning an experiment at the Los Alamos Neutron Science Center (LANSCE) to demonstrate a technique for reducing the transverse emittance of the proton beam by passing the beam through a wedge-shaped energy degrader to produce a non-symplectic correlation between transverse position and energy, then removing this correlation with a bending magnet. This technique was proposed by Peterson* in 1983. We present a specific beamline layout that is expected to mitigate several complications associated with fielding an experiment to demonstrate the technique with a low-emittance proton beam. We present simulated results and expected outcomes of this demonstration. * J. M. Peterson, Proc. of PAC 1983, pP. 2403-2405 (1984).

TUPPP038	Electron Beam Collimation for the Next Generation Light Source	undulator, gun, linac, impedance	1695
	C. Steier, P. Emma, H. Nishimura, C. F. Papadopoulos, F. Sannibale LBNL, Berkeley, California, USA
	Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The Next Generation Light Source will deliver high (MHz) repetition rate electron beams to an array of free electron lasers. Because of the significant average current in such a facility, effective beam collimation is extremely important to minimize radiation damage to undulators, prevent quenches of superconducting cavities, limit dose rates outside of the accelerator tunnel and prevent equipment damage. This paper describes the conceptual design of the collimator system, as well as the results of simulations to test its effectiveness.

TUPPP067	Collimation System Design and Performance for the SwissFEL	undulator, linac, wakefield, electron	1753
	F. Jackson, J.-L. Fernández-Hernando STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom D. Angal-Kalinin Cockcroft Institute, Warrington, Cheshire, United Kingdom H.-H. Braun, S. Reiche Paul Scherrer Institut, Villigen, Switzerland
	Electron beam collimation in the SwissFEL is required for protection of the undulators against radiation damage and demagnetization. The design for the SwissFEL collimation for the hard X-ray undulator (Aramis) includes transverse collimation in the final accelerating linac sections, plus an energy collimator in a post-linac chicane. The collimation system must provide efficient protection of the undulator for various machine modes providing varied final beam energy to the undulator. The performance of the transverse and energy collimation design is studied in simulations including evaluation of the transverse collimation for various beam energies and the effect of grazing particles on the energy collimator. Collimator wakefields are also considered.

TUPPR017	Nonlinear Post-Linac Energy Collimation System for the Compact Linear Collider	sextupole, luminosity, octupole, simulation	1846
	J. Resta-López, A. Faus-Golfe IFIC, Valencia, Spain
	Funding: FPA2010-21456-C02-01 The post-linac energy collimation system of the Compact Linear Collider (CLIC) has been designed to provide protection of the Beam Delivery System (BDS) against off-energy and mis-steered beams. The conventional baseline design consists of a two stage spoiler-absorber scheme. The CLIC energy collimators are required to withstand the impact of a full bunch train. This condition makes the energy collimator design very challenging, since the collimators have to deal with a total beam power of 14 MW at nominal energy and intensity. The increase of the transverse spot size at the collimators using nonlinear magnets could be a potential solution to guarantee the survivability of the collimators. In this paper we present an alternative nonlinear optics design for the CLIC energy collimation system. Possibilities for its optimization are discussed in view of performance simulation results.

TUPPR030	Thermo-mechanical Analysis of the CLIC Post-Linac Energy Collimators	linac, injection, simulation, betatron	1882
	J. Resta-López IFIC, Valencia, Spain J.L. Fernández-Hernando STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom A. Latina CERN, Geneva, Switzerland
	Funding: FPA2010-21456-C02-01 The post-linac energy collimation system of the Compact Linear Collider (CLIC) has been designed for passive protection of the Beam Delivery System (BDS) against mis-steered beams due to failure modes in the main linac. In this paper, a thermo-mechanical analysis of the CLIC energy collimators is presented. This study is based on simulations using the codes FLUKA and ANSYS when an entire bunch train hit the collimators. Different failure mode scenarios in the main linac are considered. Moreover, we discuss the results for different collimator materials. The aim is to improve the collimator design in order to make a reliable and robust design so that it survives without damage from the impact of a full bunch train in case of likely events generating energy errors.

TUPPR098	Comparison of LHC Collimator Beam-Based Alignment Centers to BPM-Interpolated Centers	alignment, injection, hadron, collider	2062
	G. Valentino, N.J. Sammut University of Malta, Information and Communication Technology, Msida, Malta R.W. Assmann, R. Bruce, G.J. Müller, S. Redaelli, A. Rossi, G. Valentino CERN, Geneva, Switzerland L. Lari IFIC, Valencia, Spain
	The beam centers at the Large Hadron Collider collimators are determined by beam-based alignment, where both jaws of a collimator are moved in separately until a loss spike is detected on a Beam Loss Monitor downstream. Orbit drifts of more than a few hundred micrometers cannot be tolerated, as they would reduce the efficiency of the collimation system. Beam Position Monitors (BPMs) are installed at various locations around the LHC ring, and a linear interpolation of the orbit can be obtained at the collimator positions. In this paper, the results obtained from beam-based alignment are compared with the orbit interpolated from the BPM data throughout the 2011 LHC proton run. The stability of the orbit determined by collimator alignment during the run is evaluated.

WEPPD027	Global and Local Loss Suppression in the UA9 Crystal Collimation Experiment	ion, proton, simulation, collider	2561
	W. Scandale LAL, Orsay, France S. Montesano CERN, Geneva, Switzerland
	UA9 was operated in the CERN-SPS for some years in view of investigating the feasibility of the halo collimation assisted by bent crystals. Two-millimeter-long silicon crystals, with bending angles of about 150 mirrored, are used as primary collimators. The crystal collimation process is obtained consistently through channeling with high efficiency. The loss profiles in the area of the crystal-collimator setup and in the downstream dispersion suppressor area show a steady reduction of slightly less than one order of magnitude at the onset of the channeling process. This result holds both for protons and for lead-ions. The corresponding loss map in the accelerator ring is accordingly reduced. These observations strongly support our expectation that the coherent deflection of the beam halo by a bent crystal should enhance the collimation efficiency in hadron colliders, such as LHC. for the UA9 Collaboration

WEPPD028	Collimators and Materials for High Intensity Heavy Ion Synchrotrons	ion, heavy-ion, simulation, proton	2564
	J. Stadlmann, H. Kollmus, P.J. Spiller, I. Strašík, N.A. Tahir, M. Tomut, C. Trautmann GSI, Darmstadt, Germany L.H.J. Bozyk TU Darmstadt, Darmstadt, Germany
	Funding: Funded by EU FP7 WP8 ColMat and Federal Republic of Germany The operation of high power high brightness accelerators requires huge efforts for beam cleaning and machine protection. Within the WP 8 (ColMat)of the EU research framework EuCARD we investigate new materials and methods for beam collimation and machine protection. TWe present an overview of these activities at the GSI Helmholtzzentrum für Schwerioneforschung in Darmstadt. Simulations of accidental beam losses in LHC and SIS100 have been performed. Scenarios for halo collimation of heavy ions and protons in SIS100 routine operation have been investigated. A prototype of a cryogenic collimator for charge exchange losses during intermediate charge state heavy ion operation in SIS100 has been build and tested with beam. Several candidates of advances composite materials for collimation system upgrades of present and construction of future high power accelerators have been irradiated and their properties are being characterized. Most deliverables and milestones of the R&D programm have already been reached before the end of the funding period. A summary of the obtained results will be presented.

WEPPD029	The Mechanical Design of a Collimator and Cryogenic Bypass for Installation in the Dispersion Suppressors of the LHC	cryogenics, vacuum, superconducting-magnet, shielding	2567
	D. Ramos, L. Alberty Vieira, A. Bertarelli, A. Cherif, N. Chritin, R. Claret, L. Gentini, D. Lombard, P. Minginette, P. Moyret, M. Redondas Monteserin, T. Renaglia, M.A. Timmins CERN, Geneva, Switzerland
	A project to install collimators in the dispersion suppressor regions of the LHC was launched early 2010, aiming to reduce the power deposition in superconducting magnets by a factor of 10. To be placed in the continuous arc cryostat, the design of such collimators had to comply with challenging integration, functional and time constraints. A pre-study for a cold collimator solution was launched in parallel with an alternative design consisting of a room temperature collimator and a cryogenic bypass. The second was eventually preferred, as it was based on proven LHC technologies for cryogenic, vacuum, electrical and collimator material solutions, despite the increased difficulty on the mechanical integration and assembly. This paper presents the mechanical design of a cryogenic bypass for the LHC continuous cryostat and respective collimator unit, both made to comply with the functionality of existing LHC systems. The approach taken to achieve a reliable design within schedule will be explained alongside the measures adopted to validate new solutions, in particular, when dealing with welding distortions, systems routing, thermal loads and precision mechanics.

WEPPR034	Longitudinal Phase Space Measurement for the Advanced Superconducting Test Accelerator Photoinjector	emittance, diagnostics, simulation, cavity	3009
	C.R. Prokop, P. Piot Northern Illinois University, DeKalb, Illinois, USA M.D. Church, Y.-E. Sun Fermilab, Batavia, USA
	Funding: LANL LDRD program, project 20110067DR -U.S. DOE Contract No. DE-FG02-08ER41532 and DE-AC02-07CH11359. The Advanced Superconducting Test Accelerator (ASTA) at Fermilab uses a high-brightness photoinjector capable of producing electron bunches with charges up to 3.2 nC, to be used in support of a variety of advanced accelerator R&D experiments. The photoinjector incorporates an extensive diagnostics suites including a single-shot longitudinal-phase-space diagnostics composed of a horizontally deflecting cavity followed by a vertical spectrometer. In this paper, we present the design, optimization, and performance analysis (including detrimental collective effects) of the longitudinal phase space diagnostics and especially compare two possible choices of deflecting cavity frequencies.

THEPPB005	Study on the Injection Optimization and Transverse Coupling for CSNS/RCS	injection, emittance, beam-losses, coupling	3240
	M.Y. Huang, J. Qiu, S. Wang, S.Y. Xu IHEP, Beijing, People's Republic of China
	The injection system of the China Spallation Neutron Source uses H⁻ stripping and phase space painting method to fill large ring acceptance with the linac beam of small emittance. The emittance evolution, beam losses, and collimation efficiency during the injection procedures for different injection parameters, such as the injection emittances, starting injection time, twiss parameters and momentum spread, were studied, and then the optimized injection parameters was obtained. In addition, the phase space painting scheme which also affect the emittance evolution and beam losses were simulated and the optimization range of phase space painting were obtained. There will be wobble in the power supply of the injection bumps, and the wobble effects were presented. In order to study the transverse coupling, the injection procedures for different betatron tunes and momentum spreads were studied.

THEPPB011	Apparatus and Experimental Procedures to Test Crystal Collimation	alignment, instrumentation, proton, ion	3254
	S. Montesano CERN, Geneva, Switzerland W. Scandale LAL, Orsay, France
	UA9 is an experimental setup operated in the CERN-SPS in view of investigating the feasibility of halo collimation assisted by bent crystals. The UA9 collimation system is composed only of one crystal acting as primary halo deflector and one single absorber. Different crystals are tested in turn using two-arm goniometers with an angular reproducibility of better than 10 microrad. The performance of the system are assessed through the study of the secondary and tertiary halo in critical areas, by using standard machine instrumentation and few customized equipments. The alignment of the crystal is verified by measuring the loss rate close to the crystal position. The collimation efficiency is computed by intercepting the deflected halo with a massive collimator or with an imaging device installed into a Roman Pot. The leakage of the system is evaluated in the dispersion suppressor by means of movable aperture restrictions. In this contribution the setup and the experimental methods in use are revisited in a critical way and thoroughly discussed. Particular emphasis is given on feasibility, reproducibility and effectiveness of the operational procedures. For the UA9 Collaboration

Paper

Title

Other Keywords

Page

MOEPPB008

Simulation of Hollow Electron Beam Collimation in the Fermilab Tevatron Collider

electron, simulation, quadrupole, collider

94

G. Stancari, I.A. Morozov, A. Valishev
Fermilab, Batavia, USA
D.N. Shatilov
BINP SB RAS, Novosibirsk, Russia

Funding: Fermi Research Alliance, LLC operates Fermilab under Contract DE-AC02-07CH11359 with the US Department of Energy. This work was partially supported by the US LHC Accelerator Research Program (LARP).
The concept of augmenting the conventional collimation system of high-energy storage rings with a hollow electron beam was successfully demonstrated in experiments at the Tevatron. A reliable numerical model is required for understanding particle dynamics in the presence of a hollow beam collimator. Several models were developed to describe imperfections of the electron beam profile and alignment. The features of the imperfections are estimated from electron beam profile measurements. Numerical simulations of halo removal rates are compared with experimental data taken at the Tevatron.

MOPPD072

A High Energy Collimation System for the European Spallation Source

target, beam-losses, optics, linac

529

H.D. Thomsen, A.I.S. Holm, S.P. Møller
ISA, Aarhus, Denmark

At the European Spallation Source (ESS), a ~160 m high energy beam transport (HEBT) system is to guide the high-power (5 MW) proton beam from a superconducting 2.5 GeV linac to a spallation target station. The HEBT could include a single-pass collimation system to protect all downstream accelerator components, including the vital target. The system would be built to withstand both continuous low-power losses (i.e. introduce halo reduction) and infrequent short-term, high-power beam exposure, essentially a fault scenario. Although a collimation system could reduce the uncontrolled beam losses and thus activation levels elsewhere, it takes up precious longitudinal space intended for future beam power upgrades and sets demands for the beam optics, as will be discussed. Possible materials and specifications will also be described.

MOPPD073

Development of Transportation System for Low Energy Electron Group

electron, solenoid, simulation, injection

532

S. Kato
Tohoku University, Graduate School of Science, Sendai, Japan
M. Kinsho, K. Yamamoto, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

There is a time that we want to measure the electron which occurred in the accelerator in the small situation of a noise. In that case, it is one method that we transport these electrons to the place distant form the accelerator where a noise is small. In order to realize that, development of transport line for low energy electrons is required. So, we start to develop transport line using solenoid magnets. We present status of development of this transportation system.

MOPPD074

Localization of Large Angle Foil Scattering Beam Loss Caused by Multi-Turn Charge-Exchange Injection

injection, simulation, scattering, insertion

535

S. Kato
Tohoku University, Graduate School of Science, Sendai, Japan
H. Harada, S. Hatakeyama, J. Kamiya, M. Kinsho, K. Yamamoto, Y. Yamazaki, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

In the J-PARC RCS, the significant losses were observed at the branch of H⁰ dump line and the Beam Position Monitor which was put at the downstream of the H⁰ dump branch duct. These losses were caused by the large angle scattering of the injection and circulating beam at the charge exchange foil. To realize high power operation, we have to mitigate these losses. So, we started to develop a new collimation system in the H⁰ branch duct and installed in October 2011. In order to optimize this system efficiently, we primarily focused on the relative angle of collimator block from scattering particles. We simulated behavior of particles scattered by foil and produced by collimator block and researched most optimized position and angle of the collimator block. In this process, we devised the method of angular regulation of collimator block. We present the method of angular regulation and performance of this new collimation system.

MOPPD075

Optimization of the Collimation System for the CSNS/RCS

closed-orbit, beam-losses, injection, scattering

538

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

Beam loss induced activation of the accelerator components is one of the primary concerns in designing a high intensity machine. The uncontrolled beam loss is required to be less than 1 W/m for hands-on maintenance of the machine. A two stage collimation system is designed in the Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS) to localize the beam losses in a restricted area. The parameters of the collimator are optimized in order to obtain high collimation efficiency. The final design of the collimation system is presented. The reliability of the collimation system is estimated for different working points and with closed orbit errors.

MOPPD076

Numerical Study of a Collimation System to Mitigate Beam Losses in the ESS Linac

linac, DTL, beam-losses, simulation

541

R. Miyamoto, H. Danared, M. Eshraqi, A. Ponton
ESS, Lund, Sweden

The European Spallation Source (ESS) will be a 5 MW proton linac to produce spallation neutrons. A high power linac has a very low tolerance on beam losses, typically on the order of 1 W/m, to avoid activation of the linac components; hence, emittance and halo of the beam must be well controlled throughout the linac. A system of collimators in beam transport sections has been studied and tested as a means to mitigate the beam losses in several linacs. This paper presents the result of a numerical study of a collimation system for the ESS linac.

MOPPD077

Studies for an Alternative LHC Non-Linear Collimation System

proton, sextupole, betatron, impedance

544

L. Lari, R.W. Assmann, V. Boccone, F. Cerutti, A. Mereghetti, R. Versaci, V. Vlachoudis
CERN, Geneva, Switzerland
A. Faus-Golfe, L. Lari, J. Resta-López
IFIC, Valencia, Spain

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.
A LHC nonlinear Betatron cleaning collimation system would allow larger gap for the mechanical jaws, reducing as a consequence the collimator-induced impedance, which may limit the LHC beam intensity. In this paper, the performance of the proposed system is analyzed in terms of beam losses distribution around the LHC ring and cleaning efficiency in stable physics condition at 7TeV for Beam1. Moreover, the energy deposition distribution on the machine elements is compared to the present LHC Betatron cleaning collimation system in the Point 7 Insertion Region (IR).

MOPPD079

Preliminary Thermo-Mechanical Analysis of Angular Beam Impact on LHC Collimators

simulation, kicker, superconducting-magnet, controls

550

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

Funding: This work is supported by EuCARD.
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, accident scenarios must be well studied in order to assess if the collimator design is robust against likely error scenarios. One of the catastrophic - though not very probable - accident scenarios identified is an asynchronous beam dump coupled with slight angular misalignment errors of the collimator jaw. Previous work presented a preliminary thermal evaluation of the extent of beam-induced damage for such scenarios, where it was shown that in some cases, a tilt of the jaw could actually serve to mitigate the effect of an asynchronous dump on the collimators. This paper will further analyze the response of tertiary collimators in presence of such angular jaw alignments, with the aim to identify optimal operational conditions.

MOPPD080

Improved Robustness of the LHC Collimation System by Operating with a Jaw-beam Angle

proton, radiation, scattering, alignment

553

L. Lari, R.W. Assmann, A. Rossi
CERN, Geneva, Switzerland
M. Cauchi
UoM, Msida, Malta
A. Faus-Golfe, L. Lari
IFIC, Valencia, Spain

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 robustness of the Phase I collimation system could be improved playing with the angular orientation of each single jaw. A preliminary study on the asymmetric misalignment of the collimator jaws, scanning through different jaw angles and varying beam sizes and energy, have been carried out, aiming at minimizing the energy deposited on metallic collimators, following an asynchronous dump.

MOPPD082

Recent T980 Crystal Collimation Studies at the Tevatron Exploiting a Pixel Detector System and a Multi-strip Crystal Array

proton, collider, vacuum, scattering

559

D.A. Still, G. Annala, R.A. Carrigan, A.I. Drozhdin, T.R. Johnson, N.V. Mokhov, V. Previtali, R.A. Rivera, V.D. Shiltsev, J.R. Zagel, V.V. Zvoda
Fermilab, Batavia, USA
Y.A. Chesnokov, I.A. Yazynin
IHEP, Moscow Region, Russia
V. Guidi, A. Mazzolari
INFN-Ferrara, Ferrara, Italy
Yu.M. Ivanov
PNPI, Gatchina, Leningrad District, Russia
D. Mirarchi, S. Redaelli
CERN, Geneva, Switzerland

Funding: Work supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy through the US LHC Accelerator Research Program (LARP).
With the shutdown of the Tevatron, the T-980 crystal collimation experiment at Fermilab has been successfully completed. Results of dedicated beam studies in May 2011 are described in this paper. For these studies, two multi-strip crystals were installed in the vertical goniometer. A two-plane CMS pixel detector was positioned upstream of the E03 collimator to image beam deflected by the crystals. This new enhanced hardware yielded impressive results. For the first time, a 980-GeV proton halo beam, channeled by an O-shaped crystal of the horizontal goniometer, was imaged using the pixel detector. The performance of this crystal, the first element of the collimation system, was very good. Reproducible results on the reduction of local beam losses were also obtained with an 8-strip crystal. For volume reflection these beam losses were measured with the PIN diodes and loss monitors at the E03 collimator. The long range beam losses for the channeled beam were observed using the F17 collimator one third of the ring downstream of the crystal. The measured channeling efficiency of the O-shaped crystal and the volume reflection efficiency of the 8-strip crystal were both ~70%.

TUOAC03

Status of a Single-Aperture 11 T Nb3Sn Demonstrator Dipole for LHC Upgrades

dipole, status, magnet-design, lattice

1098

A.V. Zlobin, N. Andreev, G. Apollinari, E.Z. Barzi, R. Bossert, G. Chlachidze, V. Kashikhin, A. Nobrega, I. Novitski, D. Turrioni, R. Yamada
Fermilab, Batavia, USA
B. Auchmann, M. Karppinen, L. Oberli, L. Rossi, D. Smekens
CERN, Geneva, Switzerland

Funding: Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy
The planned upgrade of the LHC collimation system includes two additional collimators to be installed in the dispersion suppressor areas of points 2, 3 and 7. The necessary longitudinal space for the collimators could be provided by replacing some 8.33 T NbTi LHC main dipoles with 11 T dipoles based on Nb3Sn superconductor and compatible with the LHC lattice and main systems. To demonstrate t his possibility Fermilab and CERN have started in 2011 a joint R&D program with the goal of building by 2014 a 5.5-m long twin-aperture dipole prototype suitable for installation in the LHC. The first step of this program is the development of a 2-m long single-aperture demonstration dipole with the nominal field of 11 T at the LHC nominal current of ~11.85 kA and 60 mm bore with ~20% margin. This paper describes the design, construction and test results of the single-aperture Nb3Sn demonstrator model for the LHC collimation system upgrade.

Slides TUOAC03 [5.812 MB]

TUPPC049

A Tapered-foil Emittance-exchange Experiment at LANSCE

emittance, proton, simulation, scattering

1278

R.C. McCrady
LANL, Los Alamos, New Mexico, USA

We are planning an experiment at the Los Alamos Neutron Science Center (LANSCE) to demonstrate a technique for reducing the transverse emittance of the proton beam by passing the beam through a wedge-shaped energy degrader to produce a non-symplectic correlation between transverse position and energy, then removing this correlation with a bending magnet. This technique was proposed by Peterson* in 1983. We present a specific beamline layout that is expected to mitigate several complications associated with fielding an experiment to demonstrate the technique with a low-emittance proton beam. We present simulated results and expected outcomes of this demonstration.
* J. M. Peterson, Proc. of PAC 1983, pP. 2403-2405 (1984).

TUPPP038

Electron Beam Collimation for the Next Generation Light Source

undulator, gun, linac, impedance

1695

C. Steier, P. Emma, H. Nishimura, C. F. Papadopoulos, F. Sannibale
LBNL, Berkeley, California, USA

Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The Next Generation Light Source will deliver high (MHz) repetition rate electron beams to an array of free electron lasers. Because of the significant average current in such a facility, effective beam collimation is extremely important to minimize radiation damage to undulators, prevent quenches of superconducting cavities, limit dose rates outside of the accelerator tunnel and prevent equipment damage. This paper describes the conceptual design of the collimator system, as well as the results of simulations to test its effectiveness.

TUPPP067

Collimation System Design and Performance for the SwissFEL

undulator, linac, wakefield, electron

1753

F. Jackson, J.-L. Fernández-Hernando
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
D. Angal-Kalinin
Cockcroft Institute, Warrington, Cheshire, United Kingdom
H.-H. Braun, S. Reiche
Paul Scherrer Institut, Villigen, Switzerland

Electron beam collimation in the SwissFEL is required for protection of the undulators against radiation damage and demagnetization. The design for the SwissFEL collimation for the hard X-ray undulator (Aramis) includes transverse collimation in the final accelerating linac sections, plus an energy collimator in a post-linac chicane. The collimation system must provide efficient protection of the undulator for various machine modes providing varied final beam energy to the undulator. The performance of the transverse and energy collimation design is studied in simulations including evaluation of the transverse collimation for various beam energies and the effect of grazing particles on the energy collimator. Collimator wakefields are also considered.

TUPPR017

Nonlinear Post-Linac Energy Collimation System for the Compact Linear Collider

sextupole, luminosity, octupole, simulation

1846

J. Resta-López, A. Faus-Golfe
IFIC, Valencia, Spain

Funding: FPA2010-21456-C02-01
The post-linac energy collimation system of the Compact Linear Collider (CLIC) has been designed to provide protection of the Beam Delivery System (BDS) against off-energy and mis-steered beams. The conventional baseline design consists of a two stage spoiler-absorber scheme. The CLIC energy collimators are required to withstand the impact of a full bunch train. This condition makes the energy collimator design very challenging, since the collimators have to deal with a total beam power of 14 MW at nominal energy and intensity. The increase of the transverse spot size at the collimators using nonlinear magnets could be a potential solution to guarantee the survivability of the collimators. In this paper we present an alternative nonlinear optics design for the CLIC energy collimation system. Possibilities for its optimization are discussed in view of performance simulation results.

TUPPR030

Thermo-mechanical Analysis of the CLIC Post-Linac Energy Collimators

linac, injection, simulation, betatron

1882

J. Resta-López
IFIC, Valencia, Spain
J.L. Fernández-Hernando
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A. Latina
CERN, Geneva, Switzerland

Funding: FPA2010-21456-C02-01
The post-linac energy collimation system of the Compact Linear Collider (CLIC) has been designed for passive protection of the Beam Delivery System (BDS) against mis-steered beams due to failure modes in the main linac. In this paper, a thermo-mechanical analysis of the CLIC energy collimators is presented. This study is based on simulations using the codes FLUKA and ANSYS when an entire bunch train hit the collimators. Different failure mode scenarios in the main linac are considered. Moreover, we discuss the results for different collimator materials. The aim is to improve the collimator design in order to make a reliable and robust design so that it survives without damage from the impact of a full bunch train in case of likely events generating energy errors.

TUPPR098

Comparison of LHC Collimator Beam-Based Alignment Centers to BPM-Interpolated Centers

alignment, injection, hadron, collider

2062

G. Valentino, N.J. Sammut
University of Malta, Information and Communication Technology, Msida, Malta
R.W. Assmann, R. Bruce, G.J. Müller, S. Redaelli, A. Rossi, G. Valentino
CERN, Geneva, Switzerland
L. Lari
IFIC, Valencia, Spain

The beam centers at the Large Hadron Collider collimators are determined by beam-based alignment, where both jaws of a collimator are moved in separately until a loss spike is detected on a Beam Loss Monitor downstream. Orbit drifts of more than a few hundred micrometers cannot be tolerated, as they would reduce the efficiency of the collimation system. Beam Position Monitors (BPMs) are installed at various locations around the LHC ring, and a linear interpolation of the orbit can be obtained at the collimator positions. In this paper, the results obtained from beam-based alignment are compared with the orbit interpolated from the BPM data throughout the 2011 LHC proton run. The stability of the orbit determined by collimator alignment during the run is evaluated.

WEPPD027

Global and Local Loss Suppression in the UA9 Crystal Collimation Experiment

ion, proton, simulation, collider

2561

W. Scandale
LAL, Orsay, France
S. Montesano
CERN, Geneva, Switzerland

UA9 was operated in the CERN-SPS for some years in view of investigating the feasibility of the halo collimation assisted by bent crystals. Two-millimeter-long silicon crystals, with bending angles of about 150 mirrored, are used as primary collimators. The crystal collimation process is obtained consistently through channeling with high efficiency. The loss profiles in the area of the crystal-collimator setup and in the downstream dispersion suppressor area show a steady reduction of slightly less than one order of magnitude at the onset of the channeling process. This result holds both for protons and for lead-ions. The corresponding loss map in the accelerator ring is accordingly reduced. These observations strongly support our expectation that the coherent deflection of the beam halo by a bent crystal should enhance the collimation efficiency in hadron colliders, such as LHC.
for the UA9 Collaboration

WEPPD028

Collimators and Materials for High Intensity Heavy Ion Synchrotrons

ion, heavy-ion, simulation, proton

2564

J. Stadlmann, H. Kollmus, P.J. Spiller, I. Strašík, N.A. Tahir, M. Tomut, C. Trautmann
GSI, Darmstadt, Germany
L.H.J. Bozyk
TU Darmstadt, Darmstadt, Germany

Funding: Funded by EU FP7 WP8 ColMat and Federal Republic of Germany
The operation of high power high brightness accelerators requires huge efforts for beam cleaning and machine protection. Within the WP 8 (ColMat)of the EU research framework EuCARD we investigate new materials and methods for beam collimation and machine protection. TWe present an overview of these activities at the GSI Helmholtzzentrum für Schwerioneforschung in Darmstadt. Simulations of accidental beam losses in LHC and SIS100 have been performed. Scenarios for halo collimation of heavy ions and protons in SIS100 routine operation have been investigated. A prototype of a cryogenic collimator for charge exchange losses during intermediate charge state heavy ion operation in SIS100 has been build and tested with beam. Several candidates of advances composite materials for collimation system upgrades of present and construction of future high power accelerators have been irradiated and their properties are being characterized. Most deliverables and milestones of the R&D programm have already been reached before the end of the funding period. A summary of the obtained results will be presented.

WEPPD029

The Mechanical Design of a Collimator and Cryogenic Bypass for Installation in the Dispersion Suppressors of the LHC

cryogenics, vacuum, superconducting-magnet, shielding

2567

D. Ramos, L. Alberty Vieira, A. Bertarelli, A. Cherif, N. Chritin, R. Claret, L. Gentini, D. Lombard, P. Minginette, P. Moyret, M. Redondas Monteserin, T. Renaglia, M.A. Timmins
CERN, Geneva, Switzerland

A project to install collimators in the dispersion suppressor regions of the LHC was launched early 2010, aiming to reduce the power deposition in superconducting magnets by a factor of 10. To be placed in the continuous arc cryostat, the design of such collimators had to comply with challenging integration, functional and time constraints. A pre-study for a cold collimator solution was launched in parallel with an alternative design consisting of a room temperature collimator and a cryogenic bypass. The second was eventually preferred, as it was based on proven LHC technologies for cryogenic, vacuum, electrical and collimator material solutions, despite the increased difficulty on the mechanical integration and assembly. This paper presents the mechanical design of a cryogenic bypass for the LHC continuous cryostat and respective collimator unit, both made to comply with the functionality of existing LHC systems. The approach taken to achieve a reliable design within schedule will be explained alongside the measures adopted to validate new solutions, in particular, when dealing with welding distortions, systems routing, thermal loads and precision mechanics.

WEPPR034

Longitudinal Phase Space Measurement for the Advanced Superconducting Test Accelerator Photoinjector

emittance, diagnostics, simulation, cavity

3009

C.R. Prokop, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
M.D. Church, Y.-E. Sun
Fermilab, Batavia, USA

Funding: LANL LDRD program, project 20110067DR -U.S. DOE Contract No. DE-FG02-08ER41532 and DE-AC02-07CH11359.
The Advanced Superconducting Test Accelerator (ASTA) at Fermilab uses a high-brightness photoinjector capable of producing electron bunches with charges up to 3.2 nC, to be used in support of a variety of advanced accelerator R&D experiments. The photoinjector incorporates an extensive diagnostics suites including a single-shot longitudinal-phase-space diagnostics composed of a horizontally deflecting cavity followed by a vertical spectrometer. In this paper, we present the design, optimization, and performance analysis (including detrimental collective effects) of the longitudinal phase space diagnostics and especially compare two possible choices of deflecting cavity frequencies.

THEPPB005

Study on the Injection Optimization and Transverse Coupling for CSNS/RCS

injection, emittance, beam-losses, coupling

3240

M.Y. Huang, J. Qiu, S. Wang, S.Y. Xu
IHEP, Beijing, People's Republic of China

The injection system of the China Spallation Neutron Source uses H⁻ stripping and phase space painting method to fill large ring acceptance with the linac beam of small emittance. The emittance evolution, beam losses, and collimation efficiency during the injection procedures for different injection parameters, such as the injection emittances, starting injection time, twiss parameters and momentum spread, were studied, and then the optimized injection parameters was obtained. In addition, the phase space painting scheme which also affect the emittance evolution and beam losses were simulated and the optimization range of phase space painting were obtained. There will be wobble in the power supply of the injection bumps, and the wobble effects were presented. In order to study the transverse coupling, the injection procedures for different betatron tunes and momentum spreads were studied.

THEPPB011

Apparatus and Experimental Procedures to Test Crystal Collimation

alignment, instrumentation, proton, ion

3254

S. Montesano
CERN, Geneva, Switzerland
W. Scandale
LAL, Orsay, France

UA9 is an experimental setup operated in the CERN-SPS in view of investigating the feasibility of halo collimation assisted by bent crystals. The UA9 collimation system is composed only of one crystal acting as primary halo deflector and one single absorber. Different crystals are tested in turn using two-arm goniometers with an angular reproducibility of better than 10 microrad. The performance of the system are assessed through the study of the secondary and tertiary halo in critical areas, by using standard machine instrumentation and few customized equipments. The alignment of the crystal is verified by measuring the loss rate close to the crystal position. The collimation efficiency is computed by intercepting the deflected halo with a massive collimator or with an imaging device installed into a Roman Pot. The leakage of the system is evaluated in the dispersion suppressor by means of movable aperture restrictions. In this contribution the setup and the experimental methods in use are revisited in a critical way and thoroughly discussed. Particular emphasis is given on feasibility, reproducibility and effectiveness of the operational procedures.
For the UA9 Collaboration