IPAC2014 - List of Keywords (collimation)

Paper	Title	Other Keywords	Page
MOOCB01	Beam-induced Quench Tests of LHC Magnets	simulation, quadrupole, experiment, beam-losses	52
	M. Sapinski, B. Auchmann, T. Bär, W. Bartmann, M. Bednarek, S. Bozyigit, C. Bracco, R. Bruce, F. Cerutti, V. Chetvertkova, K. Dahlerup-Petersen, B. Dehning, E. Effinger, J. Emery, A. Guerrero, E.B. Holzer, W. Höfle, A. Lechner, A. Priebe, S. Redaelli, B. Salvachua, R. Schmidt, N.V. Shetty, A.P. Siemko, E. Skordis, M. Solfaroli Camillocci, J. Steckert, J.A. Uythoven, D. Valuch, A.P. Verweij, J. Wenninger, D. Wollmann, M. Zerlauth, E.N. del Busto CERN, Geneva, Switzerland
	At the end of the LHC Run1 a 48-hour quench-test campaign took place to investigate the quench levels of superconducting magnets for loss durations from nanoseconds to tens of seconds. The longitudinal losses produced extended from one meter to hundreds of meters and the number of lost protons varied from 10⁸ to 10¹³. The results of these and other, previously conducted quench experiments, allow the quench levels of several types of LHC magnets under various loss conditions to be assessed. The quench levels are expected to limit LHC performance in the case of steady-state losses in the interaction regions and also in the case of fast losses initiated by dust particles all around the ring. It is therefore required to accurately adjust beam loss abort thresholds in order to maximize the operation time. A detailed discussion of these quench test results and a proposal for additional tests after the LHC restart is presented.
	Slides MOOCB01 [2.737 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOOCB01
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MOPRO021	Power Deposition in LHC Magnets With and Without Dispersion Suppressor Collimators Downstream of the Betatron Cleaning Insertion	proton, simulation, dipole, operation	112
	A. Lechner, B. Auchmann, R. Bruce, F. Cerutti, P.P. Granieri, A. Marsili, S. Redaelli, N.V. Shetty, E. Skordis, G.E. Steele, A.P. Verweij CERN, Geneva, Switzerland
	The power deposited in dispersion suppressor (DS) magnets downstream of the LHC betatron cleaning insertion is governed by off-momentum protons which predominantly originate from single-diffractive interactions in primary collimators. With higher beam energy and intensities anticipated in future operation, these clustered proton losses could possibly induce magnet quenches during periods of short beam lifetime. In this paper, we present FLUKA simulations for nominal 7 TeV operation, comparing the existing layout with alternative layouts where selected DS dipoles are substituted by pairs of shorter higher-field magnets and a collimator. Power densities predicted for different collimator settings are compared against present estimates of quench limits. Further, the expected reduction factor due to DS collimators is evaluated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO021
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MOPRO029	Feed Forward Orbit Correction in the CLIC Ring to Main LINAC Transfer Lines	emittance, kicker, extraction, simulation	131
	R. Apsimon, A. Latina, D. Schulte, J.A. Uythoven CERN, Geneva, Switzerland
	The emittance growth in the betatron collimation system of the 27 km long transfer lines between the CLIC damping rings and the main LINAC depends strongly on the transverse orbit jitter. The resulting stability requirements of the damping ring extraction elements seem extremely difficult to achieve. Position and angle feed forward systems in these long transfer lines bring the specified parameters of the extraction elements within reach. The designs of the optics and feed forward hardware are presented together with tracking simulations of the systems.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO029
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MOPRO033	Design and Feasibility Study of a Transverse Halo Collimation System for ATF2	wakefield, simulation, background, betatron	145
	N. Fuster-Martínez Valencia University, Atomic Molecular and Nuclear Physics Department, Valencia, Spain P. Bambade, S. Liu, S. Wallon LAL, Orsay, France A. Faus-Golfe, J. Resta-López IFIC, Valencia, Spain K. Kubo, T. Okugi, T. Tauchi, N. Terunuma KEK, Ibaraki, Japan I. Podadera, F. Toral CIEMAT, Madrid, Spain
	Funding: Work supported by FPA2010-21456-C02-01 and by i-link 0704 This paper presents the design of a halo collimation system for the ATF2 beamline. The main objective is the reduction of background noise that limits the performance of key diagnostic devices around the final focal point (IP), especially the Shintake Monitor (IPBSM) used for measuring the nanometer level vertical beam sizes and the future Diamond Sensor (DS) for measuring the beam halo. Beam tracking simulations have been performed to optimize the position and characteristics of the halo collimation devices. Furthermore the collimator wakefield-induced effect is being studied.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO033
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MOPRO034	Studies on Nonlinear Post-linac Protection for CLIC	sextupole, luminosity, linac, octupole	148
	J. Resta-López Cockcroft Institute, Warrington, Cheshire, United Kingdom S.T. Boogert, J. Snuverink JAI, Egham, Surrey, United Kingdom A. Faus-Golfe, J. Resta-López IFIC, Valencia, Spain
	The post-linac energy collimation system of CLIC is designed to fulfill an essential function of protection of the Beam Delivery System (BDS) against miss-steered beams generated by failure modes in the main linac. Guaranteeing the collimator survivability in case of direct beam impact is very challenging, if we take into account the need to deal with an unprecedented transverse beam energy density per beam of the order of GJ/mm². This translates into a high damage potential of uncontrolled beams. In this paper we present an alternative nonlinear energy collimation system as a potential solution to guarantee the survival of the collimators. The performance and error tolerances of this system are studied by means of beam tracking simulations, and compared with those of the conventional baseline CLIC energy collimation system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO034
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MOPRO035	Update on Nonlinear Collimation Schemes for the LHC	sextupole, optics, simulation, betatron	151
	J. Resta-López Cockcroft Institute, Warrington, Cheshire, United Kingdom A. Faus-Golfe, L. Lari, J. Resta-López IFIC, Valencia, Spain
	Funding: FP7 HL-LHC Grant Agreement 284404 In this paper we review the status of the studies on nonlinear collimation schemes for the LHC. Concretely we describe the design of a nonlinear optics for betatron cleaning in IR7. The aim is to investigate alternative nonlinear collimation systems to reduce the collimator-induced impedance that may limit the beam intensity towards the LHC luminosity upgrade. The performance of the LHC nonlinear collimation system is studied by means of tracking simulations and compared with the present LHC system. Furthermore, the advantages and possible limitations of such nonlinear collimation scheme are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO035
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MOPRO037	Collimator Fast Failure Losses for Various HL-LHC Configurations	optics, simulation, kicker, luminosity	157
	L. Lari, R. Bruce, S. Redaelli CERN, Geneva, Switzerland L. Lari IFIC, Valencia, Spain
	Funding: Research supported by EU FP7 HiLumi LHC - Grant Agreement 284404 The upgrade of the Large Hadron Collider (LHC), in terms of beam intensity and energy, implies an increasing risk of severe damage in particular in case of fast failures losses. For this reason, efforts were put in developing simulation tools to allow studies of asynchronous dump accident, including realistic failure cases for collimator settings and machine parameters like orbit and optics. The scope of these studies is to understand realistic beam loads in different collimators, in order to improve the actual LHC collimator system design, to provide feedbacks on optic design and to evaluate different mitigation actions. Simulations were set up with a modified SixTrack collimation routine able to simulate erroneous firing of a single dump kicker or the simultaneous malfunction of all the 15 kickers. In such a context, results are evaluated from the whole LHC collimation system point of view.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO037
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MOPRO039	Integrated Simulation Tools for Collimation Cleaning in HL-LHC	simulation, scattering, proton, lattice	160
	R. Bruce, C. Bracco, F. Cerutti, A. Ferrari, A. Lechner, A. Marsili, A. Mereghetti, D. Mirarchi, P.G. Ortega, D. Pastor Sinuela, S. Redaelli, A. Rossi, B. Salvachua, V. Vlachoudis CERN, Geneva, Switzerland R. Appleby, J. Molson, M. Serluca UMAN, Manchester, United Kingdom R.W. Aßmann DESY, Hamburg, Germany R.J. Barlow, H. Rafique, A.M. Toader University of Huddersfield, Huddersfield, United Kingdom S.M. Gibson, L.J. Nevay Royal Holloway, University of London, Surrey, United Kingdom L. Lari IFIC, Valencia, Spain C. Tambasco University of Rome La Sapienza, Rome, Italy
	The Large Hadron Collider is designed to accommodate an unprecedented stored beam energy of 362~MJ in the nominal configuration and about the double in the high-luminosity upgrade HL-LHC that is presently under study. This requires an efficient collimation system to protect the superconducting magnets from quenches. During the design, it is therefore very important to accurately predict the expected beam loss distributions and cleaning efficiency. For this purpose, there are several ongoing efforts in improving the existing simulation tools or developing new ones. This paper gives a brief overview and status of the different available codes.
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MOPRO040	Collimation Cleaning for HL-LHC Optics Scenarios with Error Models	simulation, alignment, optics, dipole	163
	A. Marsili, R. Bruce, S. Redaelli CERN, Geneva, Switzerland
	Funding: Research supported by EU FP7 HiLumi LHC - Grant Agreement 284404 The upgrade of the LHC collimation system in view of the High-Luminosity upgrade of the Large Hadron Collider (LHC) foresees, amongst other scenarios, local collimation in the dispersion suppressors (DS) of IR7. Layouts have been worked out which rely on using stronger and short bending dipoles to free space for a collimator in the cold DS. In this paper, the effectiveness of the proposed layouts is studied with different imperfection models such as collimator alignment, jaw tilt and surface errors, optics errors and aperture imperfections. The effect of local DS collimation on the global losses around the ring is also addressed for different optics configurations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO040
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MOPRO042	Cleaning Performance with 11T Dipoles and Local Dispersion Suppressor Collimation at the LHC	dipole, optics, simulation, proton	170
	R. Bruce, A. Marsili, S. Redaelli CERN, Geneva, Switzerland
	The limiting location of the present LHC machine in terms of losses on cold magnets are the dispersion suppressors downstream of the betatron collimation insertion (IR7). These losses are dominated by off-energy protons that have by-passed the upstream secondary collimation system but are lost where the dispersion starts to rise. A solution under consideration for intercepting these losses is the addition of new collimators in the dispersive area. This paper discusses first a proposition for the new layout in the DS, where space is made for the new collimators by replacing an existing dipole by shorter and stronger magnets. Furthermore, simulations with SixTrack are presented, which quantify the gain in cleaning from the new collimators.
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MOPRO043	Handling 1 MW Losses with the LHC Collimation System	simulation, beam-losses, betatron, proton	174
	B. Salvachua, R. Bruce, F. Carra, M. Cauchi, E.B. Holzer, W. Höfle, D. Jacquet, L. Lari, D. Mirarchi, E. Nebot Del Busto, S. Redaelli, A. Rossi, M. Sapinski, R. Schmidt, G. Valentino, D. Valuch, J. Wenninger, D. Wollmann, M. Zerlauth CERN, Geneva, Switzerland M. Cauchi UoM, Msida, Malta L. Lari IFIC, Valencia, Spain
	Funding: Research supported by EU FP7 HiLumi LHC (Grant agree. 284404) The LHC superconducting magnets in the dispersion suppressor of IR7 are the most exposed to beam losses leaking from the betatron collimation system and represent the main limitation for the halo cleaning. In 2013, quench tests were performed at 4 TeV to improve the quench limit estimates, which determine the maximum allowed beam loss rate for a given collimation cleaning. The main goal of the collimation quench test was to try to quench the magnets by increasing losses at the collimators. Losses of up to 1 MW over a few seconds were generated by blowing up the beam, achieving total losses of about 5.8 MJ. These controlled losses exceeded by a factor 2 the collimation design value, and the magnets did not quench.
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MOPRO044	Construction and Bench Testing of a Prototype Rotatable Collimator for the LHC	vacuum, impedance, controls, operation	178
	T.W. Markiewicz, E.L. Bong, L. Keller SLAC, Menlo Park, California, USA O. Aberle, A. Bertarelli, P. Gradassi, A. Marsili, S. Redaelli, A. Rossi, B. Salvachua, G. Valentino CERN, Geneva, Switzerland
	Funding: This work partially supported by the U.S. Department of Energy through the US LHC Accelerator Research Program (LARP) and contract DE-AC02-76SF00515. A second generation prototype rotatable collimator has been fabricated at SLAC and delivered to CERN for further vacuum, metrology, function and impedance tests. The design features two cylindrical Glidcop jaws designed to each absorb 12kW of beam in steady state and up to 60kW in transitory beam loss with no damage and minimal thermal distortion. The design is motivated by the use of a radiation resistant high Z low impedance readily available material. A vacuum rotation mechanism using the standard LHC collimation jaw positioning motor system allows each jaw to be rotated to present a new 2cm high surface to the beam if the jaw surface were to be damaged by multiple full intensity beam bunch impacts in a asynchronous beam abort. Design modifications to improve on the first generation prototype, pre-delivery functional tests performed at SLAC and post-delivery test results at CERN are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO044
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MOPRO046	Comparison of MERLIN/SixTrack for LHC Collimation Studies	optics, scattering, simulation, proton	185
	M. Serluca, R. Appleby, J. Molson UMAN, Manchester, United Kingdom R.J. Barlow, H. Rafique, A.M. Toader University of Huddersfield, Huddersfield, United Kingdom R. Bruce, A. Marsili, S. Redaelli, B. Salvachua CERN, Geneva, Switzerland C. Tambasco University of Rome La Sapienza, Rome, Italy
	Simulations of the LHC collimation system have been carried out in previous years with the well known SixTrack code with collimation features. MERLIN is a C++ accelerator physics library that has been extended to perform collimation studies. The main features of the code are: its modular nature, allowing the user to easily implement new physics processes such as resistive wakefields and synchrotron radiation, improved scattering routines and the MPI protocol for parallel execution. MERLIN has been configured to use the same scattering routines as SixTrack in order to benchmark the code for the LHC collimation system. In this paper we present a detailed comparison between MERLIN and SixTrack for optics and cleaning inefficiency calculation.
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MOPRO116	Mechanical Engineering and Design of Novel Collimators for HL-LHC	impedance, operation, proton, experiment	369
	F. Carra, A. Bertarelli, A. Dallocchio, L. Gentini, P. Gradassi, A. Manousos, N. Mariani, G. Maîtrejean, N. Mounet, E. Quaranta, S. Redaelli, V. Vlachoudis CERN, Geneva, Switzerland
	In view of LHC intensity upgrades, collimator materials may become a limit to the machine performance: the high RF impedance of Carbon-Carbon composites can lead to beam instabilities, while the Tungsten alloy adopted in tertiary collimators exhibits low robustness in case of beam-induced accidents. An R&D program has been pursued to develop new materials overcoming such limitations. Molybdenum-Graphite, in addition to its outstanding thermal conductivity, can be coated with pure molybdenum, reducing collimator impedance by a factor of 10. A new secondary collimator is being designed around this novel composite. New high-melting materials are also proposed to improve the robustness of tertiary collimators. All the new collimators will be equipped with BPMs, significantly enhancing the alignment speed and the beta-star reach. This implies additional constraints of space, as well as detailed static and fatigue calculations on cables and connectors. This paper describes the mechanical design and the engineering calculations of such future collimators, focusing on the study via state-of-the-art numerical methods of interactions between the particle beams and the new materials adopted.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO116
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MOPRI077	Hi-Lumi LHC Collimation Studies with MERLIN Code	optics, scattering, proton, simulation	784
	M. Serluca, R. Appleby, J. Molson UMAN, Manchester, United Kingdom R.J. Barlow, H. Rafique, A.M. Toader University of Huddersfield, Huddersfield, United Kingdom
	The collimation system is key to the successful operation of the LHC. Measurements and simulations of the previous run at 4 TeV have shown that the system is ready for the next step, running at 7 TeV, but at the same time some sensitive cleaning locations have been identified. In particular the dispersion suppressors downstream of the betatron cleaning region in IR7 are sensitive to single diffractive scattered protons from the collimator jaws. These particles can lead to magnet quenching. The MERLIN C++ library has been developed to exploit the functionality of an object oriented code, with improved collective effects and scattering routines. New single diffractive and elastic scattering routines, based on a fit of existing experimental data with the Regge theory of soft interactions of high energy scattering, is implemented in MERLIN. In this paper we present the impact of the new single diffractive scattering physics on the cleaning inefficiency of the LHC collimation system for the Achromatic Telescope Squeezing (ATS) PreSqueeze optics scheme, for the HL-LHC project. The results are compared with the same loss map calculated using a SixTrack+K2 like scattering routine.
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MOPRI096	The New Transfer Line Collimation System for the LHC High Luminosity Era	optics, injection, luminosity, extraction	839
	V. Kain, C. Bracco, B. Goddard, F.L. Maciariello, M. Meddahi, A. Mereghetti, G.E. Steele, F.M. Velotti CERN, Geneva, Switzerland E. Gianfelice-Wendt Fermilab, Batavia, Illinois, USA
	A set of passive absorbers is located at the end of each of the 3 km long injection lines to protect the LHC in case of failures during the extraction process from the LHC’s last pre-injector or the beam transfer itself. In case of an erroneous extraction, the absorbers have to attenuate the beam to a safe level and be robust enough themselves to survive the impact. These requirements are difficult to fulfil with the very bright and intense beams produced by the LHC injectors for the high luminosity era. This paper revisits the requirements for the SPS-to-LHC transfer line collimation system and the adapted strategy to fulfill these for the LHC high luminosity operation. A possible solution for the new transfer line collimation system is presented.
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MOPRI098	Design Studies of the Upgraded Collimation System in the SPS-to-LHC Transfer Lines	luminosity, injection, simulation, optics	845
	A. Mereghetti, C. Bracco, F. Cerutti, B. Goddard, J. Hrivnak, V. Kain, F.L. Maciariello, M. Meddahi, G.E. Steele CERN, Geneva, Switzerland R. Appleby UMAN, Manchester, United Kingdom
	In the framework of the LHC Injectors Upgrade (LIU) Project, the collimators in the SPS-to-LHC transfer lines are presently under re-design, in order to cope with the unprecedented beam intensities and emittances required by the High Luminosity LHC (HL-LHC). Factors ruling the design phase are the robustness of the jaws on one side and, on the other side, the proton absorption and the emittance blow-up, essential for an effective protection of the equipment in the LHC injection regions and the LHC machine. In view of the new design, based on the one of the currently installed TCDI collimators and past investigations, the FLUKA Monte Carlo code is used to address these two factors. The present studies are intended to give essential feedback to the identification of viable solutions.
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MOPRI106	Simulation Study of Beam Halo Collimation in the Heavy-ion Synchrotron SIS 100	ion, simulation, heavy-ion, injection	870
	I.A. Prokhorov TEMF, TU Darmstadt, Darmstadt, Germany O. Boine-Frankenheim, I. Strašík GSI, Darmstadt, Germany
	Funding: Work is supported by German Federal Ministry of Education and Research (BMBF) contract no. 05P12RDRBM The FAIR synchrotron SIS-100 will be operated with high-intensity proton and heavy-ion beams. The collimation system should prevent beam loss induced degradation of the vacuum, activation of the accelerator structure and magnet quenches. A conventional two-stage betatron collimation system is considered for the operation with protons and fully-stripped ions. Particle tracking and ion-collimator interaction simulations of the collimation system were performed. The angular and momentum distributions of the scattered halo particles were described using analytical models and numerical tools like ATIMA and FLUKA. MADX was used for the multi-pass tracking simulations. The results obtained for the collimation cleaning efficiency as a function of the ion species and beam energy together with the detailed beam losses distributions along the ring circumference are presented. This work highlights the main aspects of the collimation of fully-stripped ion beams in the intermediate energy range using conventional two-stage systems.
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MOPRI109	High-Power Proton-Synchrotron Collimation Studies	proton, synchrotron, quadrupole, target	879
	A. Alekou, Y. Papaphilippou CERN, Geneva, Switzerland D. Spitzbart TU Vienna, Wien, Austria
	The High-Power Proton-Synchrotron (HP-PS) will be delivering a 2 MW proton beam to a fixed target in order to produce neutrinos within the LAGUNA-LBNO project. A mechanical collimation system is essential to prevent lost particles from hitting the super-feric dipoles of the HP-PS ring and to also limit the equipment irradiation close to the beam. This paper presents how the efficiency of the HP-PS collimator system is optimised with respect to the change of the collimators’ thickness, material and beam halo size.
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MOPRI110	Final Layout and Expected Cleaning for the First Crystal-assisted Collimation Test at the LHC	simulation, proton, injection, ion	882
	D. Mirarchi, S. Montesano, S. Redaelli, W. Scandale CERN, Geneva, Switzerland F. Galluccio INFN-Napoli, Napoli, Italy A.M. Taratin JINR, Dubna, Moscow Region, Russia
	The installation in the CERN Large Hadron Collider (LHC) of two crystals in the horizontal and vertical planes was accomplished during the present LHC long shutdown (LS1) for crystal collimation studies. An appropriate layout was designed to demonstrate the principle feasibility of crystal collimation at the LHC. Extensive simulation campaigns were made to evaluate different crystal positions and parameters, in order to ensure that the main goals of these first feasibility tests in the LHC are within reach. In this paper, the final layout is presented. An overview of the considerations behind the design choices and the crystal parameters is given, and the expected performance of the system is discussed.
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MOPRI111	Improvements of the Crystal Routine for Collimation Studies	proton, simulation, scattering, extraction	886
	D. Mirarchi, S. Redaelli, W. Scandale CERN, Geneva, Switzerland A.M. Taratin JINR, Dubna, Moscow Region, Russia I.A. Yazynin IHEP, Moscow Region, Russia
	A routine has been implemented to simulate interactions of protons with bent crystals in the collimation version of \texttt{SixTrack}. This routine is optimized in view of producing high-statistics tracking simulations of collimation cleaning assisted by bent crystals. Fine tuning and comparisons with experimental data of coherent effects which a particle can experience in a bent crystal have been carried out. The data taken with 400 GeV beams at the CERN-SPS North Area in the framework of the UA9 experiment are used to benchmark the routine. Further checks on low probability interactions have been made, leading to significant improvements in the description of interactions with crystals. Comparisons with other simulations tools are used to increase our confidence in the scaling to higher energies.
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TUOBA01	Electron Lenses for the Large Hadron Collider	electron, collider, controls, operation	918
	G. Stancari, A. Valishev Fermilab, Batavia, Illinois, USA R. Bruce, S. Redaelli, A. Rossi, B. Salvachua CERN, Geneva, Switzerland
	Funding: Fermi Research Alliance, LLC operates Fermilab under Contract DE-AC02-07CH11359 with the US Department of Energy. Research supported in part by US LARP and EU FP7 HiLumi LHC, Grant Agreement 284404. Electron lenses are pulsed, magnetically confined electron beams whose current-density profile is shaped to obtain the desired effect on the circulating beam. Electron lenses were used in the Fermilab Tevatron collider for bunch-by-bunch compensation of long-range beam-beam tune shifts, for removal of uncaptured particles in the abort gap, for preliminary experiments on head-on beam-beam compensation, and for the demonstration of halo scraping with hollow electron beams. Electron lenses for beam-beam compensation are being commissioned in RHIC at BNL. Within the US LHC Accelerator Research Program and the European HiLumi LHC Design Study, hollow electron beam collimation was studied as an option to complement the collimation system for the LHC upgrades. This project is moving towards a technical design in 2014, with the goal to build the devices in 2015-2017, after resuming LHC operations and re-assessing needs and requirements at 6.5 TeV. Because of their electric charge and the absence of materials close to the proton beam, electron lenses may also provide an alternative to wires for long-range beam-beam compensation in LHC luminosity upgrade scenarios with small crossing angles.
	Slides TUOBA01 [9.709 MB]
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TUPRO095	Using One-dimensional Hall Probe to Measure the Solenoid Magnet for CSNS/RCS	solenoid, linac, synchrotron, insertion	1262
	Z. Zhang, S. Li, F. Long, X.J. Sun IHEP, Beijing, People's Republic of China
	Abstract CSNS(China Spallation Neutron Source) construction is expected to start in 2010 and will last 6.5 years. A long beam transport line is followed with the DTL linac to send the beam a rapid cycling synchrotron (RCS) accelerator. The beam will be focused by the solenoid magnet. This magnet will be located in LEBT system. It has been used with one-dimensional Hall probe to measurement by Institute of High Energy Physics, China. After the measurement, the measurement results meet the design requirements.
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WEPME047	CERN Vacuum System Activities during the Long Shutdown 1: the LHC Beam Vacuum	vacuum, experiment, electron, cryogenics	2375
	V. Baglin, G. Bregliozzi, P. Chiggiato, J.M. Jimenez, G. Lanza CERN, Geneva, Switzerland
	After the Long Shutdown 1 (LS1) and the consolidation of the magnet bus bars, the CERN Large Hadron Collider (LHC) will operate with nominal beam parameters. Larger beam energy, beam intensities and luminosity are expected. Despite the very good performance of the beam vacuum system during the 2010-12 physics run (Run 1), some particular areas require attention for repair, consolidation and upgrade. Among the main activities, a large campaign aiming at the repair of the RF bridges of some vacuum modules is conducted. Moreover, consolidation of the cryogenic beam vacuum systems with burst disk for safety reasons is implemented. In addition, NEG cartridges, NEG coated inserts and new instruments for the vacuum system upgrade are installed. Besides these activities, repair, consolidation and upgrades of other beam equipment such as collimators, kickers and beam instrumentations are carried out. In this paper, the motivation and the description for such activities, together with the expected beam vacuum performance after LS1, are described in detail.
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WEPRI098	QUENCH PROTECTION STUDIES OF 11T Nb3Sn DIPOLE MODELS FOR LHC UPGRADES	dipole, extraction, injection, simulation	2725
	A.V. Zlobin, G. Chlachidze, A. Nobrega, I. Novitski Fermilab, Batavia, Illinois, USA M. Karppinen 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 CERN and FNAL are developing 11 T Nb3Sn dipole magnets for the LHC collimation system upgrade. Due to the large stored energy, protection of these magnets during a quench is a challenging problem. This paper reports the results of experimental studies of key quench protection parameters including longitudinal and radial quench propagation in the coil, coil heating due to a quench, and energy extraction and quench-back effect. The studies were performed using a 1 m long 11 T Nb3Sn dipole coil tested in a magnetic mirror configuration.
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THPME091	Beam Halo Measurements using Wire Scanners at ATF2	background, detector, photon, experiment	3445
	S. Liu, P. Bambade LAL, Orsay, France S. Bai, J. Gao, D. Wang IHEP, Beijing, People's Republic of China A. Faus-Golfe, N. Fuster-Martínez IFIC, Valencia, Spain T. Tauchi, N. Terunuma KEK, Ibaraki, Japan
	Funding: Chinese Scholarship Council, FPA2010-21456-C02-01 and i-link 0704 Beam halo hitting on the beam pipe after the Interaction Point (IP) can generate a large amount of background for the measurements of the nano meter beam size using the laser interferometer beam size monitor (Shintake monitor) at ATF2. In order to investigate the beam halo transverse distribution, a diamond detector will be installed downstream of the IP. A feasibility study of a transverse halo collimation system to reduce the background for these measurements is also in progress. Prior to the diamond detector installation, a first attempt of beam halo measurements have been performed in 2013 using the currently installed wire scanners. Modeling of the beam halo distribution in the extraction (EXT) line was done and compared with the old modeling for ATF. Beam halo measurements were also done using the post-IP wire scanner to investigate the beam halo distribution at post-IP. Work supported by Chinese Scholarship Council, FPA2010-21456-C02-01 and i-link 0704
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Paper

Title

Other Keywords

Page

MOOCB01

Beam-induced Quench Tests of LHC Magnets

simulation, quadrupole, experiment, beam-losses

52

M. Sapinski, B. Auchmann, T. Bär, W. Bartmann, M. Bednarek, S. Bozyigit, C. Bracco, R. Bruce, F. Cerutti, V. Chetvertkova, K. Dahlerup-Petersen, B. Dehning, E. Effinger, J. Emery, A. Guerrero, E.B. Holzer, W. Höfle, A. Lechner, A. Priebe, S. Redaelli, B. Salvachua, R. Schmidt, N.V. Shetty, A.P. Siemko, E. Skordis, M. Solfaroli Camillocci, J. Steckert, J.A. Uythoven, D. Valuch, A.P. Verweij, J. Wenninger, D. Wollmann, M. Zerlauth, E.N. del Busto
CERN, Geneva, Switzerland

At the end of the LHC Run1 a 48-hour quench-test campaign took place to investigate the quench levels of superconducting magnets for loss durations from nanoseconds to tens of seconds. The longitudinal losses produced extended from one meter to hundreds of meters and the number of lost protons varied from 10⁸ to 10¹³. The results of these and other, previously conducted quench experiments, allow the quench levels of several types of LHC magnets under various loss conditions to be assessed. The quench levels are expected to limit LHC performance in the case of steady-state losses in the interaction regions and also in the case of fast losses initiated by dust particles all around the ring. It is therefore required to accurately adjust beam loss abort thresholds in order to maximize the operation time. A detailed discussion of these quench test results and a proposal for additional tests after the LHC restart is presented.

Slides MOOCB01 [2.737 MB]

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MOPRO021

Power Deposition in LHC Magnets With and Without Dispersion Suppressor Collimators Downstream of the Betatron Cleaning Insertion

proton, simulation, dipole, operation

112

A. Lechner, B. Auchmann, R. Bruce, F. Cerutti, P.P. Granieri, A. Marsili, S. Redaelli, N.V. Shetty, E. Skordis, G.E. Steele, A.P. Verweij
CERN, Geneva, Switzerland

The power deposited in dispersion suppressor (DS) magnets downstream of the LHC betatron cleaning insertion is governed by off-momentum protons which predominantly originate from single-diffractive interactions in primary collimators. With higher beam energy and intensities anticipated in future operation, these clustered proton losses could possibly induce magnet quenches during periods of short beam lifetime. In this paper, we present FLUKA simulations for nominal 7 TeV operation, comparing the existing layout with alternative layouts where selected DS dipoles are substituted by pairs of shorter higher-field magnets and a collimator. Power densities predicted for different collimator settings are compared against present estimates of quench limits. Further, the expected reduction factor due to DS collimators is evaluated.

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MOPRO029

Feed Forward Orbit Correction in the CLIC Ring to Main LINAC Transfer Lines

emittance, kicker, extraction, simulation

131

R. Apsimon, A. Latina, D. Schulte, J.A. Uythoven
CERN, Geneva, Switzerland

The emittance growth in the betatron collimation system of the 27 km long transfer lines between the CLIC damping rings and the main LINAC depends strongly on the transverse orbit jitter. The resulting stability requirements of the damping ring extraction elements seem extremely difficult to achieve. Position and angle feed forward systems in these long transfer lines bring the specified parameters of the extraction elements within reach. The designs of the optics and feed forward hardware are presented together with tracking simulations of the systems.

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MOPRO033

Design and Feasibility Study of a Transverse Halo Collimation System for ATF2

wakefield, simulation, background, betatron

145

N. Fuster-Martínez
Valencia University, Atomic Molecular and Nuclear Physics Department, Valencia, Spain
P. Bambade, S. Liu, S. Wallon
LAL, Orsay, France
A. Faus-Golfe, J. Resta-López
IFIC, Valencia, Spain
K. Kubo, T. Okugi, T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan
I. Podadera, F. Toral
CIEMAT, Madrid, Spain

Funding: Work supported by FPA2010-21456-C02-01 and by i-link 0704
This paper presents the design of a halo collimation system for the ATF2 beamline. The main objective is the reduction of background noise that limits the performance of key diagnostic devices around the final focal point (IP), especially the Shintake Monitor (IPBSM) used for measuring the nanometer level vertical beam sizes and the future Diamond Sensor (DS) for measuring the beam halo. Beam tracking simulations have been performed to optimize the position and characteristics of the halo collimation devices. Furthermore the collimator wakefield-induced effect is being studied.

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MOPRO034

Studies on Nonlinear Post-linac Protection for CLIC

sextupole, luminosity, linac, octupole

148

J. Resta-López
Cockcroft Institute, Warrington, Cheshire, United Kingdom
S.T. Boogert, J. Snuverink
JAI, Egham, Surrey, United Kingdom
A. Faus-Golfe, J. Resta-López
IFIC, Valencia, Spain

The post-linac energy collimation system of CLIC is designed to fulfill an essential function of protection of the Beam Delivery System (BDS) against miss-steered beams generated by failure modes in the main linac. Guaranteeing the collimator survivability in case of direct beam impact is very challenging, if we take into account the need to deal with an unprecedented transverse beam energy density per beam of the order of GJ/mm². This translates into a high damage potential of uncontrolled beams. In this paper we present an alternative nonlinear energy collimation system as a potential solution to guarantee the survival of the collimators. The performance and error tolerances of this system are studied by means of beam tracking simulations, and compared with those of the conventional baseline CLIC energy collimation system.

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MOPRO035

Update on Nonlinear Collimation Schemes for the LHC

sextupole, optics, simulation, betatron

151

J. Resta-López
Cockcroft Institute, Warrington, Cheshire, United Kingdom
A. Faus-Golfe, L. Lari, J. Resta-López
IFIC, Valencia, Spain

Funding: FP7 HL-LHC Grant Agreement 284404
In this paper we review the status of the studies on nonlinear collimation schemes for the LHC. Concretely we describe the design of a nonlinear optics for betatron cleaning in IR7. The aim is to investigate alternative nonlinear collimation systems to reduce the collimator-induced impedance that may limit the beam intensity towards the LHC luminosity upgrade. The performance of the LHC nonlinear collimation system is studied by means of tracking simulations and compared with the present LHC system. Furthermore, the advantages and possible limitations of such nonlinear collimation scheme are discussed.

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MOPRO037

Collimator Fast Failure Losses for Various HL-LHC Configurations

optics, simulation, kicker, luminosity

157

L. Lari, R. Bruce, S. Redaelli
CERN, Geneva, Switzerland
L. Lari
IFIC, Valencia, Spain

Funding: Research supported by EU FP7 HiLumi LHC - Grant Agreement 284404
The upgrade of the Large Hadron Collider (LHC), in terms of beam intensity and energy, implies an increasing risk of severe damage in particular in case of fast failures losses. For this reason, efforts were put in developing simulation tools to allow studies of asynchronous dump accident, including realistic failure cases for collimator settings and machine parameters like orbit and optics. The scope of these studies is to understand realistic beam loads in different collimators, in order to improve the actual LHC collimator system design, to provide feedbacks on optic design and to evaluate different mitigation actions. Simulations were set up with a modified SixTrack collimation routine able to simulate erroneous firing of a single dump kicker or the simultaneous malfunction of all the 15 kickers. In such a context, results are evaluated from the whole LHC collimation system point of view.

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MOPRO039

Integrated Simulation Tools for Collimation Cleaning in HL-LHC

simulation, scattering, proton, lattice

160

R. Bruce, C. Bracco, F. Cerutti, A. Ferrari, A. Lechner, A. Marsili, A. Mereghetti, D. Mirarchi, P.G. Ortega, D. Pastor Sinuela, S. Redaelli, A. Rossi, B. Salvachua, V. Vlachoudis
CERN, Geneva, Switzerland
R. Appleby, J. Molson, M. Serluca
UMAN, Manchester, United Kingdom
R.W. Aßmann
DESY, Hamburg, Germany
R.J. Barlow, H. Rafique, A.M. Toader
University of Huddersfield, Huddersfield, United Kingdom
S.M. Gibson, L.J. Nevay
Royal Holloway, University of London, Surrey, United Kingdom
L. Lari
IFIC, Valencia, Spain
C. Tambasco
University of Rome La Sapienza, Rome, Italy

The Large Hadron Collider is designed to accommodate an unprecedented stored beam energy of 362~MJ in the nominal configuration and about the double in the high-luminosity upgrade HL-LHC that is presently under study. This requires an efficient collimation system to protect the superconducting magnets from quenches. During the design, it is therefore very important to accurately predict the expected beam loss distributions and cleaning efficiency. For this purpose, there are several ongoing efforts in improving the existing simulation tools or developing new ones. This paper gives a brief overview and status of the different available codes.

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MOPRO040

Collimation Cleaning for HL-LHC Optics Scenarios with Error Models

simulation, alignment, optics, dipole

163

A. Marsili, R. Bruce, S. Redaelli
CERN, Geneva, Switzerland

Funding: Research supported by EU FP7 HiLumi LHC - Grant Agreement 284404
The upgrade of the LHC collimation system in view of the High-Luminosity upgrade of the Large Hadron Collider (LHC) foresees, amongst other scenarios, local collimation in the dispersion suppressors (DS) of IR7. Layouts have been worked out which rely on using stronger and short bending dipoles to free space for a collimator in the cold DS. In this paper, the effectiveness of the proposed layouts is studied with different imperfection models such as collimator alignment, jaw tilt and surface errors, optics errors and aperture imperfections. The effect of local DS collimation on the global losses around the ring is also addressed for different optics configurations.

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MOPRO042

Cleaning Performance with 11T Dipoles and Local Dispersion Suppressor Collimation at the LHC

dipole, optics, simulation, proton

170

R. Bruce, A. Marsili, S. Redaelli
CERN, Geneva, Switzerland

The limiting location of the present LHC machine in terms of losses on cold magnets are the dispersion suppressors downstream of the betatron collimation insertion (IR7). These losses are dominated by off-energy protons that have by-passed the upstream secondary collimation system but are lost where the dispersion starts to rise. A solution under consideration for intercepting these losses is the addition of new collimators in the dispersive area. This paper discusses first a proposition for the new layout in the DS, where space is made for the new collimators by replacing an existing dipole by shorter and stronger magnets. Furthermore, simulations with SixTrack are presented, which quantify the gain in cleaning from the new collimators.

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MOPRO043

Handling 1 MW Losses with the LHC Collimation System

simulation, beam-losses, betatron, proton

174

B. Salvachua, R. Bruce, F. Carra, M. Cauchi, E.B. Holzer, W. Höfle, D. Jacquet, L. Lari, D. Mirarchi, E. Nebot Del Busto, S. Redaelli, A. Rossi, M. Sapinski, R. Schmidt, G. Valentino, D. Valuch, J. Wenninger, D. Wollmann, M. Zerlauth
CERN, Geneva, Switzerland
M. Cauchi
UoM, Msida, Malta
L. Lari
IFIC, Valencia, Spain

Funding: Research supported by EU FP7 HiLumi LHC (Grant agree. 284404)
The LHC superconducting magnets in the dispersion suppressor of IR7 are the most exposed to beam losses leaking from the betatron collimation system and represent the main limitation for the halo cleaning. In 2013, quench tests were performed at 4 TeV to improve the quench limit estimates, which determine the maximum allowed beam loss rate for a given collimation cleaning. The main goal of the collimation quench test was to try to quench the magnets by increasing losses at the collimators. Losses of up to 1 MW over a few seconds were generated by blowing up the beam, achieving total losses of about 5.8 MJ. These controlled losses exceeded by a factor 2 the collimation design value, and the magnets did not quench.

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MOPRO044

Construction and Bench Testing of a Prototype Rotatable Collimator for the LHC

vacuum, impedance, controls, operation

178

T.W. Markiewicz, E.L. Bong, L. Keller
SLAC, Menlo Park, California, USA
O. Aberle, A. Bertarelli, P. Gradassi, A. Marsili, S. Redaelli, A. Rossi, B. Salvachua, G. Valentino
CERN, Geneva, Switzerland

Funding: This work partially supported by the U.S. Department of Energy through the US LHC Accelerator Research Program (LARP) and contract DE-AC02-76SF00515.
A second generation prototype rotatable collimator has been fabricated at SLAC and delivered to CERN for further vacuum, metrology, function and impedance tests. The design features two cylindrical Glidcop jaws designed to each absorb 12kW of beam in steady state and up to 60kW in transitory beam loss with no damage and minimal thermal distortion. The design is motivated by the use of a radiation resistant high Z low impedance readily available material. A vacuum rotation mechanism using the standard LHC collimation jaw positioning motor system allows each jaw to be rotated to present a new 2cm high surface to the beam if the jaw surface were to be damaged by multiple full intensity beam bunch impacts in a asynchronous beam abort. Design modifications to improve on the first generation prototype, pre-delivery functional tests performed at SLAC and post-delivery test results at CERN are presented.

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MOPRO046

Comparison of MERLIN/SixTrack for LHC Collimation Studies

optics, scattering, simulation, proton

185

M. Serluca, R. Appleby, J. Molson
UMAN, Manchester, United Kingdom
R.J. Barlow, H. Rafique, A.M. Toader
University of Huddersfield, Huddersfield, United Kingdom
R. Bruce, A. Marsili, S. Redaelli, B. Salvachua
CERN, Geneva, Switzerland
C. Tambasco
University of Rome La Sapienza, Rome, Italy

Simulations of the LHC collimation system have been carried out in previous years with the well known SixTrack code with collimation features. MERLIN is a C++ accelerator physics library that has been extended to perform collimation studies. The main features of the code are: its modular nature, allowing the user to easily implement new physics processes such as resistive wakefields and synchrotron radiation, improved scattering routines and the MPI protocol for parallel execution. MERLIN has been configured to use the same scattering routines as SixTrack in order to benchmark the code for the LHC collimation system. In this paper we present a detailed comparison between MERLIN and SixTrack for optics and cleaning inefficiency calculation.

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MOPRO116

Mechanical Engineering and Design of Novel Collimators for HL-LHC

impedance, operation, proton, experiment

369

F. Carra, A. Bertarelli, A. Dallocchio, L. Gentini, P. Gradassi, A. Manousos, N. Mariani, G. Maîtrejean, N. Mounet, E. Quaranta, S. Redaelli, V. Vlachoudis
CERN, Geneva, Switzerland

In view of LHC intensity upgrades, collimator materials may become a limit to the machine performance: the high RF impedance of Carbon-Carbon composites can lead to beam instabilities, while the Tungsten alloy adopted in tertiary collimators exhibits low robustness in case of beam-induced accidents. An R&D program has been pursued to develop new materials overcoming such limitations. Molybdenum-Graphite, in addition to its outstanding thermal conductivity, can be coated with pure molybdenum, reducing collimator impedance by a factor of 10. A new secondary collimator is being designed around this novel composite. New high-melting materials are also proposed to improve the robustness of tertiary collimators. All the new collimators will be equipped with BPMs, significantly enhancing the alignment speed and the beta-star reach. This implies additional constraints of space, as well as detailed static and fatigue calculations on cables and connectors. This paper describes the mechanical design and the engineering calculations of such future collimators, focusing on the study via state-of-the-art numerical methods of interactions between the particle beams and the new materials adopted.

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MOPRI077

Hi-Lumi LHC Collimation Studies with MERLIN Code

optics, scattering, proton, simulation

784

M. Serluca, R. Appleby, J. Molson
UMAN, Manchester, United Kingdom
R.J. Barlow, H. Rafique, A.M. Toader
University of Huddersfield, Huddersfield, United Kingdom

The collimation system is key to the successful operation of the LHC. Measurements and simulations of the previous run at 4 TeV have shown that the system is ready for the next step, running at 7 TeV, but at the same time some sensitive cleaning locations have been identified. In particular the dispersion suppressors downstream of the betatron cleaning region in IR7 are sensitive to single diffractive scattered protons from the collimator jaws. These particles can lead to magnet quenching. The MERLIN C++ library has been developed to exploit the functionality of an object oriented code, with improved collective effects and scattering routines. New single diffractive and elastic scattering routines, based on a fit of existing experimental data with the Regge theory of soft interactions of high energy scattering, is implemented in MERLIN. In this paper we present the impact of the new single diffractive scattering physics on the cleaning inefficiency of the LHC collimation system for the Achromatic Telescope Squeezing (ATS) PreSqueeze optics scheme, for the HL-LHC project. The results are compared with the same loss map calculated using a SixTrack+K2 like scattering routine.

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MOPRI096

The New Transfer Line Collimation System for the LHC High Luminosity Era

optics, injection, luminosity, extraction

839

V. Kain, C. Bracco, B. Goddard, F.L. Maciariello, M. Meddahi, A. Mereghetti, G.E. Steele, F.M. Velotti
CERN, Geneva, Switzerland
E. Gianfelice-Wendt
Fermilab, Batavia, Illinois, USA

A set of passive absorbers is located at the end of each of the 3 km long injection lines to protect the LHC in case of failures during the extraction process from the LHC’s last pre-injector or the beam transfer itself. In case of an erroneous extraction, the absorbers have to attenuate the beam to a safe level and be robust enough themselves to survive the impact. These requirements are difficult to fulfil with the very bright and intense beams produced by the LHC injectors for the high luminosity era. This paper revisits the requirements for the SPS-to-LHC transfer line collimation system and the adapted strategy to fulfill these for the LHC high luminosity operation. A possible solution for the new transfer line collimation system is presented.

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MOPRI098

Design Studies of the Upgraded Collimation System in the SPS-to-LHC Transfer Lines

luminosity, injection, simulation, optics

845

A. Mereghetti, C. Bracco, F. Cerutti, B. Goddard, J. Hrivnak, V. Kain, F.L. Maciariello, M. Meddahi, G.E. Steele
CERN, Geneva, Switzerland
R. Appleby
UMAN, Manchester, United Kingdom

In the framework of the LHC Injectors Upgrade (LIU) Project, the collimators in the SPS-to-LHC transfer lines are presently under re-design, in order to cope with the unprecedented beam intensities and emittances required by the High Luminosity LHC (HL-LHC). Factors ruling the design phase are the robustness of the jaws on one side and, on the other side, the proton absorption and the emittance blow-up, essential for an effective protection of the equipment in the LHC injection regions and the LHC machine. In view of the new design, based on the one of the currently installed TCDI collimators and past investigations, the FLUKA Monte Carlo code is used to address these two factors. The present studies are intended to give essential feedback to the identification of viable solutions.

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MOPRI106

Simulation Study of Beam Halo Collimation in the Heavy-ion Synchrotron SIS 100

ion, simulation, heavy-ion, injection

870

I.A. Prokhorov
TEMF, TU Darmstadt, Darmstadt, Germany
O. Boine-Frankenheim, I. Strašík
GSI, Darmstadt, Germany

Funding: Work is supported by German Federal Ministry of Education and Research (BMBF) contract no. 05P12RDRBM
The FAIR synchrotron SIS-100 will be operated with high-intensity proton and heavy-ion beams. The collimation system should prevent beam loss induced degradation of the vacuum, activation of the accelerator structure and magnet quenches. A conventional two-stage betatron collimation system is considered for the operation with protons and fully-stripped ions. Particle tracking and ion-collimator interaction simulations of the collimation system were performed. The angular and momentum distributions of the scattered halo particles were described using analytical models and numerical tools like ATIMA and FLUKA. MADX was used for the multi-pass tracking simulations. The results obtained for the collimation cleaning efficiency as a function of the ion species and beam energy together with the detailed beam losses distributions along the ring circumference are presented. This work highlights the main aspects of the collimation of fully-stripped ion beams in the intermediate energy range using conventional two-stage systems.

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MOPRI109

High-Power Proton-Synchrotron Collimation Studies

proton, synchrotron, quadrupole, target

879

A. Alekou, Y. Papaphilippou
CERN, Geneva, Switzerland
D. Spitzbart
TU Vienna, Wien, Austria

The High-Power Proton-Synchrotron (HP-PS) will be delivering a 2 MW proton beam to a fixed target in order to produce neutrinos within the LAGUNA-LBNO project. A mechanical collimation system is essential to prevent lost particles from hitting the super-feric dipoles of the HP-PS ring and to also limit the equipment irradiation close to the beam. This paper presents how the efficiency of the HP-PS collimator system is optimised with respect to the change of the collimators’ thickness, material and beam halo size.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI109

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MOPRI110

Final Layout and Expected Cleaning for the First Crystal-assisted Collimation Test at the LHC

simulation, proton, injection, ion

882

D. Mirarchi, S. Montesano, S. Redaelli, W. Scandale
CERN, Geneva, Switzerland
F. Galluccio
INFN-Napoli, Napoli, Italy
A.M. Taratin
JINR, Dubna, Moscow Region, Russia

The installation in the CERN Large Hadron Collider (LHC) of two crystals in the horizontal and vertical planes was accomplished during the present LHC long shutdown (LS1) for crystal collimation studies. An appropriate layout was designed to demonstrate the principle feasibility of crystal collimation at the LHC. Extensive simulation campaigns were made to evaluate different crystal positions and parameters, in order to ensure that the main goals of these first feasibility tests in the LHC are within reach. In this paper, the final layout is presented. An overview of the considerations behind the design choices and the crystal parameters is given, and the expected performance of the system is discussed.

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MOPRI111

Improvements of the Crystal Routine for Collimation Studies

proton, simulation, scattering, extraction

886

D. Mirarchi, S. Redaelli, W. Scandale
CERN, Geneva, Switzerland
A.M. Taratin
JINR, Dubna, Moscow Region, Russia
I.A. Yazynin
IHEP, Moscow Region, Russia

A routine has been implemented to simulate interactions of protons with bent crystals in the collimation version of \texttt{SixTrack}. This routine is optimized in view of producing high-statistics tracking simulations of collimation cleaning assisted by bent crystals. Fine tuning and comparisons with experimental data of coherent effects which a particle can experience in a bent crystal have been carried out. The data taken with 400 GeV beams at the CERN-SPS North Area in the framework of the UA9 experiment are used to benchmark the routine. Further checks on low probability interactions have been made, leading to significant improvements in the description of interactions with crystals. Comparisons with other simulations tools are used to increase our confidence in the scaling to higher energies.

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TUOBA01

Electron Lenses for the Large Hadron Collider

electron, collider, controls, operation

918

G. Stancari, A. Valishev
Fermilab, Batavia, Illinois, USA
R. Bruce, S. Redaelli, A. Rossi, B. Salvachua
CERN, Geneva, Switzerland

Funding: Fermi Research Alliance, LLC operates Fermilab under Contract DE-AC02-07CH11359 with the US Department of Energy. Research supported in part by US LARP and EU FP7 HiLumi LHC, Grant Agreement 284404.
Electron lenses are pulsed, magnetically confined electron beams whose current-density profile is shaped to obtain the desired effect on the circulating beam. Electron lenses were used in the Fermilab Tevatron collider for bunch-by-bunch compensation of long-range beam-beam tune shifts, for removal of uncaptured particles in the abort gap, for preliminary experiments on head-on beam-beam compensation, and for the demonstration of halo scraping with hollow electron beams. Electron lenses for beam-beam compensation are being commissioned in RHIC at BNL. Within the US LHC Accelerator Research Program and the European HiLumi LHC Design Study, hollow electron beam collimation was studied as an option to complement the collimation system for the LHC upgrades. This project is moving towards a technical design in 2014, with the goal to build the devices in 2015-2017, after resuming LHC operations and re-assessing needs and requirements at 6.5 TeV. Because of their electric charge and the absence of materials close to the proton beam, electron lenses may also provide an alternative to wires for long-range beam-beam compensation in LHC luminosity upgrade scenarios with small crossing angles.

Slides TUOBA01 [9.709 MB]

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TUPRO095

Using One-dimensional Hall Probe to Measure the Solenoid Magnet for CSNS/RCS

solenoid, linac, synchrotron, insertion

1262

Z. Zhang, S. Li, F. Long, X.J. Sun
IHEP, Beijing, People's Republic of China

Abstract CSNS(China Spallation Neutron Source) construction is expected to start in 2010 and will last 6.5 years. A long beam transport line is followed with the DTL linac to send the beam a rapid cycling synchrotron (RCS) accelerator. The beam will be focused by the solenoid magnet. This magnet will be located in LEBT system. It has been used with one-dimensional Hall probe to measurement by Institute of High Energy Physics, China. After the measurement, the measurement results meet the design requirements.

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WEPME047

CERN Vacuum System Activities during the Long Shutdown 1: the LHC Beam Vacuum

vacuum, experiment, electron, cryogenics

2375

V. Baglin, G. Bregliozzi, P. Chiggiato, J.M. Jimenez, G. Lanza
CERN, Geneva, Switzerland

After the Long Shutdown 1 (LS1) and the consolidation of the magnet bus bars, the CERN Large Hadron Collider (LHC) will operate with nominal beam parameters. Larger beam energy, beam intensities and luminosity are expected. Despite the very good performance of the beam vacuum system during the 2010-12 physics run (Run 1), some particular areas require attention for repair, consolidation and upgrade. Among the main activities, a large campaign aiming at the repair of the RF bridges of some vacuum modules is conducted. Moreover, consolidation of the cryogenic beam vacuum systems with burst disk for safety reasons is implemented. In addition, NEG cartridges, NEG coated inserts and new instruments for the vacuum system upgrade are installed. Besides these activities, repair, consolidation and upgrades of other beam equipment such as collimators, kickers and beam instrumentations are carried out. In this paper, the motivation and the description for such activities, together with the expected beam vacuum performance after LS1, are described in detail.

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WEPRI098

QUENCH PROTECTION STUDIES OF 11T Nb3Sn DIPOLE MODELS FOR LHC UPGRADES

dipole, extraction, injection, simulation

2725

A.V. Zlobin, G. Chlachidze, A. Nobrega, I. Novitski
Fermilab, Batavia, Illinois, USA
M. Karppinen
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
CERN and FNAL are developing 11 T Nb3Sn dipole magnets for the LHC collimation system upgrade. Due to the large stored energy, protection of these magnets during a quench is a challenging problem. This paper reports the results of experimental studies of key quench protection parameters including longitudinal and radial quench propagation in the coil, coil heating due to a quench, and energy extraction and quench-back effect. The studies were performed using a 1 m long 11 T Nb3Sn dipole coil tested in a magnetic mirror configuration.

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THPME091

Beam Halo Measurements using Wire Scanners at ATF2

background, detector, photon, experiment

3445

S. Liu, P. Bambade
LAL, Orsay, France
S. Bai, J. Gao, D. Wang
IHEP, Beijing, People's Republic of China
A. Faus-Golfe, N. Fuster-Martínez
IFIC, Valencia, Spain
T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan

Funding: Chinese Scholarship Council, FPA2010-21456-C02-01 and i-link 0704
Beam halo hitting on the beam pipe after the Interaction Point (IP) can generate a large amount of background for the measurements of the nano meter beam size using the laser interferometer beam size monitor (Shintake monitor) at ATF2. In order to investigate the beam halo transverse distribution, a diamond detector will be installed downstream of the IP. A feasibility study of a transverse halo collimation system to reduce the background for these measurements is also in progress. Prior to the diamond detector installation, a first attempt of beam halo measurements have been performed in 2013 using the currently installed wire scanners. Modeling of the beam halo distribution in the extraction (EXT) line was done and compared with the old modeling for ATF. Beam halo measurements were also done using the post-IP wire scanner to investigate the beam halo distribution at post-IP.
Work supported by Chinese Scholarship Council, FPA2010-21456-C02-01 and i-link 0704

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