IPAC2014 - Classification: 01 Circular and Linear Colliders / T19 Collimation

Paper	Title	Page
MOPRO021	Power Deposition in LHC Magnets With and Without Dispersion Suppressor Collimators Downstream of the Betatron Cleaning Insertion	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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MOPRO033	Design and Feasibility Study of a Transverse Halo Collimation System for ATF2	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	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	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	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	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	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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MOPRO041	Multi-turn Tracking of Collision Products at the LHC	166
	A. Marsili, R. Bruce, F. Cerutti, L.S. Esposito, S. Redaelli CERN, Geneva, Switzerland
	Funding: Research supported by EU FP7 HiLumi LHC - Grant Agreement 284404 The luminosity expected at the interaction points in LHC at 7 TeV will be unprecedented, up to 1034 cm−2 s−1 . Part of the debris produced by the collisions is lost locally im- mediately downstream the Interaction Point (IP), in the matching section and dispersion suppressor. In this paper, the dynamics of collision debris protons is discussed. First, the loss distributions close to the collision points, simulated with two codes – SixTrack and FLUKA – are compared for different layout configurations. Then, SixTrack is used to simulate the fraction of protons that have undergone inelastic interactions with smaller energy and and betatron offsets, which could travel for several turns around the ring and might be lost in other collimation insertions. A preliminary comparison is made between the resulting loss distribution and measurements.
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MOPRO042	Cleaning Performance with 11T Dipoles and Local Dispersion Suppressor Collimation at the LHC	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO042
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MOPRO043	Handling 1 MW Losses with the LHC Collimation System	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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MOPRO045	Beam Delivery Simulation: BDSIM - Development & Optimisation	182
	L.J. Nevay, S.T. Boogert, H. Garcia, S.M. Gibson, R. Kwee-Hinzmann, J. Snuverink JAI, Egham, Surrey, United Kingdom L.C. Deacon UCL, London, United Kingdom
	Funding: Research supported by FP7 HiLumi LHC - grant agreement 284404. Beam Delivery Simulation (BDSIM) is a Geant4 and C++ based particle tracking code that seamlessly tracks particles through accelerators and detectors, including the full range of particle interaction physics processes from Geant4. BDSIM has been successfully used to model beam loss and background conditions for many current and future linear accelerators such as the Accelerator Test Facility 2 (ATF2) and the International Linear Collider (ILC). Current developments extend its application for use with storage rings, in particular for the Large Hadron Collider (LHC) and the High Luminosity upgrade project (HL-LHC). This paper presents the latest results from using BDSIM to model the LHC as well as the developments underway to improve performance.
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MOPRO046	Comparison of MERLIN/SixTrack for LHC Collimation Studies	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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MOPRI077	Hi-Lumi LHC Collimation Studies with MERLIN Code	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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Paper

Title

Page

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

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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MOPRO033

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

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 •

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MOPRO034

Studies on Nonlinear Post-linac Protection for CLIC

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 •

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MOPRO035

Update on Nonlinear Collimation Schemes for the LHC

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

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

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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO039

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MOPRO040

Collimation Cleaning for HL-LHC Optics Scenarios with Error Models

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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MOPRO041

Multi-turn Tracking of Collision Products at the LHC

166

A. Marsili, R. Bruce, F. Cerutti, L.S. Esposito, S. Redaelli
CERN, Geneva, Switzerland

Funding: Research supported by EU FP7 HiLumi LHC - Grant Agreement 284404
The luminosity expected at the interaction points in LHC at 7 TeV will be unprecedented, up to 1034 cm−2 s−1 . Part of the debris produced by the collisions is lost locally im- mediately downstream the Interaction Point (IP), in the matching section and dispersion suppressor. In this paper, the dynamics of collision debris protons is discussed. First, the loss distributions close to the collision points, simulated with two codes – SixTrack and FLUKA – are compared for different layout configurations. Then, SixTrack is used to simulate the fraction of protons that have undergone inelastic interactions with smaller energy and and betatron offsets, which could travel for several turns around the ring and might be lost in other collimation insertions. A preliminary comparison is made between the resulting loss distribution and measurements.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO041

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MOPRO042

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

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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO042

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MOPRO043

Handling 1 MW Losses with the LHC Collimation System

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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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO043

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MOPRO045

Beam Delivery Simulation: BDSIM - Development & Optimisation

182

L.J. Nevay, S.T. Boogert, H. Garcia, S.M. Gibson, R. Kwee-Hinzmann, J. Snuverink
JAI, Egham, Surrey, United Kingdom
L.C. Deacon
UCL, London, United Kingdom

Funding: Research supported by FP7 HiLumi LHC - grant agreement 284404.
Beam Delivery Simulation (BDSIM) is a Geant4 and C++ based particle tracking code that seamlessly tracks particles through accelerators and detectors, including the full range of particle interaction physics processes from Geant4. BDSIM has been successfully used to model beam loss and background conditions for many current and future linear accelerators such as the Accelerator Test Facility 2 (ATF2) and the International Linear Collider (ILC). Current developments extend its application for use with storage rings, in particular for the Large Hadron Collider (LHC) and the High Luminosity upgrade project (HL-LHC). This paper presents the latest results from using BDSIM to model the LHC as well as the developments underway to improve performance.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO045

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MOPRO046

Comparison of MERLIN/SixTrack for LHC Collimation Studies

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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MOPRI077

Hi-Lumi LHC Collimation Studies with MERLIN Code

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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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI077

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