IPAC2022 - Classification: MC1: Circular and Linear Colliders / T19: Collimation

Paper	Title	Page
WEPOST016	Development of Collimation Simulations for the FCC-ee	1718
	A. Abramov, R. Bruce, M. Hofer, G. Iadarola, S. Redaelli CERN, Meyrin, Switzerland F.S. Carlier, T. Pieloni, M. Rakic EPFL, Lausanne, Switzerland L.J. Nevay JAI, Egham, Surrey, United Kingdom S.M. White ESRF, Grenoble, France
	A collimation system is under study for the FCC-ee to protect the machine from the multi-MJ electron and positron beams and limit the backgrounds to the detectors. One of the key aspects of the collimation system design is the setup of simulation studies combining particle tracking and scattering in the collimators. The tracking must include effects important for electron beam single-particle dynamics in the FCC-ee, such as synchrotron radiation. For collimation, an aperture model and particle-matter interactions for electrons are required. There are currently no established simulation frameworks that include all the required features. The latest developments of an integrated framework for multi-turn collimation studies in the FCC-ee are presented. The framework is based on an interface between tracking codes, pyAT and Xtrack, and a particle-matter interaction code, BDSIM, based on Geant4. Promising alternative simulation codes and frameworks are also discussed. The challenges are outlined, and the first results are presented, including preliminary loss maps for the FCC-ee.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST016
About •	Received ※ 07 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 29 June 2022
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WEPOST017	Design of a Collimation Section for the FCC-ee	1722
	M. Hofer, A. Abramov, R. Bruce, K. Oide, F. Zimmermann CERN, Meyrin, Switzerland M. Moudgalya, T. Pieloni EPFL, Lausanne, Switzerland K. Oide KEK, Ibaraki, Japan
	The design parameters of the FCC-ee foresee operation with a total stored beam energy of about 20 MJ, exceeding those of previous lepton colliders by almost two orders of magnitude. Given the inherent damage potential, a halo collimation system is studied to protect the machine hardware, in particular superconducting equipment such as the final focus quadrupoles, from sudden beam loss. The different constraints that led to dedicating one straight section to collimation will be outlined. In addition, a preliminary layout and optics for a collimation insertion are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST017
About •	Received ※ 07 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 25 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPOST018	Power Deposition Studies for Crystal-Based Heavy Ion Collimation in the LHC	1726
SUSPMF007	use link to see paper's listing under its alternate paper code
	J.B. Potoine, R. Bruce, R. Cai, L.S. Esposito, P.D. Hermes, A. Lechner, S. Redaelli, A. Waets CERN, Meyrin, Switzerland F. Wrobel IES, Montpellier, France
	The LHC heavy-ion program with 208Pb⁸²⁺ beams is foreseen to benefit from a significant intensity upgrade in 2022. A performance limitation may arise from ion fragments scattered out of the collimators in the betatron cleaning insertion, which risk quenching superconducting magnets during periods of short beam lifetime. In order to mitigate this risk, an alternative collimation technique, relying on bent crystals as primary collimators, will be used in future heavy-ion runs. In this paper, we study the power deposition in superconducting magnets by means of FLUKA shower simulations, comparing the standard collimation system against the crystal-based one. The studies focus on the dispersion suppressor regions downstream of the betatron cleaning insertion, where the ion fragment losses are the highest. Based on these studies, we quantify the expected quench margin expected in future runs with 208Pb⁸²⁺ beams.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST018
About •	Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 24 June 2022 — Issue date ※ 03 July 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPOST019	Benchmarks of Energy Deposition Studies for Heavy-Ion Collimation Losses at the LHC	1730
	J.B. Potoine, R. Bruce, R. Cai, P.D. Hermes, A. Lechner, S. Redaelli, A. Waets CERN, Meyrin, Switzerland F. Wrobel IES, Montpellier, France
	During some periods in its second physics run (2015-2018), the LHC has been operated with 208Pb⁸²⁺ ion beams at an energy of 6.37 ZTeV. The LHC is equipped with a betatron collimation system, which intercepts the transverse beam halo and protects sensitive equipment such as superconducting magnets against beam losses. However, hadronic fragmentation and electromagnetic dissociation of heavy ions in collimators generate off-rigidity particles, which can be lost in the downstream dispersion suppressor, putting the magnets at risk to quench. An accurate modelling of the beam-induced energy deposition in the collimation system and superconducting magnets is important for quantifying possible performance limitations arising from magnet quenches. In this paper, we compare FLUKA shower simulations against beam loss monitor measurements recorded during the 2018 208Pb⁸²⁺ run. In particular, we investigate fast beam loss events, which lead to recurring beam aborts in 2018 operation. Based on these studies, we assess the ability of the simulation model to reproduce the observed loss patterns in the collimation region and dispersion suppressor.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST019
About •	Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 23 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Development of Collimation Simulations for the FCC-ee

1718

A. Abramov, R. Bruce, M. Hofer, G. Iadarola, S. Redaelli
CERN, Meyrin, Switzerland
F.S. Carlier, T. Pieloni, M. Rakic
EPFL, Lausanne, Switzerland
L.J. Nevay
JAI, Egham, Surrey, United Kingdom
S.M. White
ESRF, Grenoble, France

A collimation system is under study for the FCC-ee to protect the machine from the multi-MJ electron and positron beams and limit the backgrounds to the detectors. One of the key aspects of the collimation system design is the setup of simulation studies combining particle tracking and scattering in the collimators. The tracking must include effects important for electron beam single-particle dynamics in the FCC-ee, such as synchrotron radiation. For collimation, an aperture model and particle-matter interactions for electrons are required. There are currently no established simulation frameworks that include all the required features. The latest developments of an integrated framework for multi-turn collimation studies in the FCC-ee are presented. The framework is based on an interface between tracking codes, pyAT and Xtrack, and a particle-matter interaction code, BDSIM, based on Geant4. Promising alternative simulation codes and frameworks are also discussed. The challenges are outlined, and the first results are presented, including preliminary loss maps for the FCC-ee.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST016

About •

Received ※ 07 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 29 June 2022

Cite •

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

WEPOST017

Design of a Collimation Section for the FCC-ee

1722

M. Hofer, A. Abramov, R. Bruce, K. Oide, F. Zimmermann
CERN, Meyrin, Switzerland
M. Moudgalya, T. Pieloni
EPFL, Lausanne, Switzerland
K. Oide
KEK, Ibaraki, Japan

The design parameters of the FCC-ee foresee operation with a total stored beam energy of about 20 MJ, exceeding those of previous lepton colliders by almost two orders of magnitude. Given the inherent damage potential, a halo collimation system is studied to protect the machine hardware, in particular superconducting equipment such as the final focus quadrupoles, from sudden beam loss. The different constraints that led to dedicating one straight section to collimation will be outlined. In addition, a preliminary layout and optics for a collimation insertion are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST017

About •

Received ※ 07 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 25 June 2022

Cite •

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

WEPOST018

Power Deposition Studies for Crystal-Based Heavy Ion Collimation in the LHC

1726

SUSPMF007

use link to see paper's listing under its alternate paper code

J.B. Potoine, R. Bruce, R. Cai, L.S. Esposito, P.D. Hermes, A. Lechner, S. Redaelli, A. Waets
CERN, Meyrin, Switzerland
F. Wrobel
IES, Montpellier, France

The LHC heavy-ion program with 208Pb⁸²⁺ beams is foreseen to benefit from a significant intensity upgrade in 2022. A performance limitation may arise from ion fragments scattered out of the collimators in the betatron cleaning insertion, which risk quenching superconducting magnets during periods of short beam lifetime. In order to mitigate this risk, an alternative collimation technique, relying on bent crystals as primary collimators, will be used in future heavy-ion runs. In this paper, we study the power deposition in superconducting magnets by means of FLUKA shower simulations, comparing the standard collimation system against the crystal-based one. The studies focus on the dispersion suppressor regions downstream of the betatron cleaning insertion, where the ion fragment losses are the highest. Based on these studies, we quantify the expected quench margin expected in future runs with 208Pb⁸²⁺ beams.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST018

About •

Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 24 June 2022 — Issue date ※ 03 July 2022

Cite •

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

WEPOST019

Benchmarks of Energy Deposition Studies for Heavy-Ion Collimation Losses at the LHC

1730

J.B. Potoine, R. Bruce, R. Cai, P.D. Hermes, A. Lechner, S. Redaelli, A. Waets
CERN, Meyrin, Switzerland
F. Wrobel
IES, Montpellier, France

During some periods in its second physics run (2015-2018), the LHC has been operated with 208Pb⁸²⁺ ion beams at an energy of 6.37 ZTeV. The LHC is equipped with a betatron collimation system, which intercepts the transverse beam halo and protects sensitive equipment such as superconducting magnets against beam losses. However, hadronic fragmentation and electromagnetic dissociation of heavy ions in collimators generate off-rigidity particles, which can be lost in the downstream dispersion suppressor, putting the magnets at risk to quench. An accurate modelling of the beam-induced energy deposition in the collimation system and superconducting magnets is important for quantifying possible performance limitations arising from magnet quenches. In this paper, we compare FLUKA shower simulations against beam loss monitor measurements recorded during the 2018 208Pb⁸²⁺ run. In particular, we investigate fast beam loss events, which lead to recurring beam aborts in 2018 operation. Based on these studies, we assess the ability of the simulation model to reproduce the observed loss patterns in the collimation region and dispersion suppressor.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST019

About •

Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 23 June 2022

Cite •

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