IPAC2014 - List of Authors (Marsili, A.)

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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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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MOPRO044	Construction and Bench Testing of a Prototype Rotatable Collimator for the LHC	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	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO046
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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

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPRO044

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

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

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO046

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)