IPAC2016 - List of Authors (Valloni, A.)

Paper	Title	Page
WEPMW007	Validation of Off-momentum Cleaning Performance of the LHC Collimation System	2427
	B. Salvachua, P. Baudrenghien, R. Bruce, H. Garcia, P.D. Hermes, S. Jackson, M. Jaussi, A. Mereghetti, D. Mirarchi, S. Redaelli, H. Timko, G. Valentino, A. Valloni CERN, Geneva, Switzerland R. Kwee-Hinzmann Royal Holloway, University of London, Surrey, United Kingdom
	The LHC collimation system is designed to provide effective cleaning against losses coming from off-momentum particles, either due to un-captured beam or to an unexpected RF frequency change. For this reason the LHC is equipped with a hierarchy of collimators in IR3: primary, secondary and absorber collimators. After every collimator alignment or change of machine configuration the off-momentum cleaning efficiency is validated with loss maps at low intensity. We describe here the improved technique used in 2015 to generate such loss maps without completely dumping the beam into the collimators. The achieved performance of the collimation system for momentum cleaning is reviewed.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW007
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WEPMW034	First Operational Experience with Embedded Collimator BPMs in the LHC	2510
	G. Valentino, G. Baud, R. Bruce, M. Gąsior, J. Olexa, S. Redaelli, A. Valloni, J. Wenninger CERN, Geneva, Switzerland
	During Long Shutdown 1, 18 Large Hadron Collider (LHC) collimators were replaced with a new design, in which beam position monitor (BPM) pick-up buttons are embedded in the collimator jaws. The BPMs provide a direct measurement of the beam orbit at the collimators, and therefore can be used to align the collimators more quickly than using the standard technique which relies on feedback from beam losses. Online orbit measurements also mean that margins in the collimation hierarchy placed specifically to cater for unknown orbit drifts can be reduced, therefore increasing the beta-star and luminosity reach of the LHC. In this paper, the first operational results are presented, including a comparison with the standard alignment technique and a fill-to-fill analysis of the measured orbit in different machine modes in the first year of running after the shutdown.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW034
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WEPMW036	MERLIN Cleaning Studies with Advanced Collimator Materials for HL-LHC	2514
	A. Valloni, R. Bruce, A. Mereghetti, E. Quaranta, S. Redaelli CERN, Geneva, Switzerland R.B. Appleby UMAN, Manchester, United Kingdom J. Molson LAL, Orsay, France H. Rafique University of Huddersfield, Huddersfield, United Kingdom
	The challenges of the High-Luminosity upgrade of the Large Hadron Collider require improving the beam collimation system. An intense R&D program has started at CERN to explore novel materials for new collimator jaws to improve robustness and reduce impedance. Particle tracking simulations of collimation efficiency are performed using the code MERLIN which has been extended to include new materials based on composites. After presenting two different implementations of composite materials tested in MERLIN, we present simulation studies with the aim of studying the effect of the advanced collimators on the LHC beam cleaning.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW036
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WEPMW037	MERLIN Simulations of the LHC Collimation System with 6.5 TeV Beams	2518
	A. Valloni Rome University La Sapienza, Roma, Italy R.B. Appleby, S.C. Tygier UMAN, Manchester, United Kingdom R. Bruce, A. Mereghetti, S. Redaelli CERN, Geneva, Switzerland J. Molson LAL, Orsay, France H. Rafique University of Huddersfield, Huddersfield, United Kingdom
	The accelerator physics code MERLIN has been extended in many areas to make detailed studies of the LHC collima- tion system and calculate loss maps from beam halo losses. Large scale tracking simulations have been produced for the 2015 run configuration at 6.5 TeV. We present results of cleaning inefficiency simulations of the LHC's multi-stage collimation system along with a detailed comparison be- tween MERLIN, SixTrack, and measured beam losses.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW037
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Paper

Title

Page

Validation of Off-momentum Cleaning Performance of the LHC Collimation System

2427

B. Salvachua, P. Baudrenghien, R. Bruce, H. Garcia, P.D. Hermes, S. Jackson, M. Jaussi, A. Mereghetti, D. Mirarchi, S. Redaelli, H. Timko, G. Valentino, A. Valloni
CERN, Geneva, Switzerland
R. Kwee-Hinzmann
Royal Holloway, University of London, Surrey, United Kingdom

The LHC collimation system is designed to provide effective cleaning against losses coming from off-momentum particles, either due to un-captured beam or to an unexpected RF frequency change. For this reason the LHC is equipped with a hierarchy of collimators in IR3: primary, secondary and absorber collimators. After every collimator alignment or change of machine configuration the off-momentum cleaning efficiency is validated with loss maps at low intensity. We describe here the improved technique used in 2015 to generate such loss maps without completely dumping the beam into the collimators. The achieved performance of the collimation system for momentum cleaning is reviewed.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW007

Export •

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

WEPMW034

First Operational Experience with Embedded Collimator BPMs in the LHC

2510

G. Valentino, G. Baud, R. Bruce, M. Gąsior, J. Olexa, S. Redaelli, A. Valloni, J. Wenninger
CERN, Geneva, Switzerland

During Long Shutdown 1, 18 Large Hadron Collider (LHC) collimators were replaced with a new design, in which beam position monitor (BPM) pick-up buttons are embedded in the collimator jaws. The BPMs provide a direct measurement of the beam orbit at the collimators, and therefore can be used to align the collimators more quickly than using the standard technique which relies on feedback from beam losses. Online orbit measurements also mean that margins in the collimation hierarchy placed specifically to cater for unknown orbit drifts can be reduced, therefore increasing the beta-star and luminosity reach of the LHC. In this paper, the first operational results are presented, including a comparison with the standard alignment technique and a fill-to-fill analysis of the measured orbit in different machine modes in the first year of running after the shutdown.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW034

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

WEPMW036

MERLIN Cleaning Studies with Advanced Collimator Materials for HL-LHC

2514

A. Valloni, R. Bruce, A. Mereghetti, E. Quaranta, S. Redaelli
CERN, Geneva, Switzerland
R.B. Appleby
UMAN, Manchester, United Kingdom
J. Molson
LAL, Orsay, France
H. Rafique
University of Huddersfield, Huddersfield, United Kingdom

The challenges of the High-Luminosity upgrade of the Large Hadron Collider require improving the beam collimation system. An intense R&D program has started at CERN to explore novel materials for new collimator jaws to improve robustness and reduce impedance. Particle tracking simulations of collimation efficiency are performed using the code MERLIN which has been extended to include new materials based on composites. After presenting two different implementations of composite materials tested in MERLIN, we present simulation studies with the aim of studying the effect of the advanced collimators on the LHC beam cleaning.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW036

Export •

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

WEPMW037

MERLIN Simulations of the LHC Collimation System with 6.5 TeV Beams

2518

A. Valloni
Rome University La Sapienza, Roma, Italy
R.B. Appleby, S.C. Tygier
UMAN, Manchester, United Kingdom
R. Bruce, A. Mereghetti, S. Redaelli
CERN, Geneva, Switzerland
J. Molson
LAL, Orsay, France
H. Rafique
University of Huddersfield, Huddersfield, United Kingdom

The accelerator physics code MERLIN has been extended in many areas to make detailed studies of the LHC collima- tion system and calculate loss maps from beam halo losses. Large scale tracking simulations have been produced for the 2015 run configuration at 6.5 TeV. We present results of cleaning inefficiency simulations of the LHC's multi-stage collimation system along with a detailed comparison be- tween MERLIN, SixTrack, and measured beam losses.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW037

Export •

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