CERN Accelerating science

Article
Title	Mitigating Collimation Impedance and Improving Halo Cleaning with New Optics and Settings Strategy of the HL-LHC Betatron Collimation System
Author(s)	Lindström, Bjorn (CERN) ; Bruce, Roderik (CERN) ; Buffat, Xavier (CERN) ; De Maria, Riccardo (CERN) ; Giacomel, Lorenzo (CERN) ; Hermes, Pascal (CERN) ; Mirarchi, Daniele (CERN) ; Mounet, Nicolas (CERN) ; Persson, Tobias (CERN) ; Redaelli, Stefano (CERN) ; Tomás García, Rogelio (CERN) ; Van der Veken, Frederik (CERN) ; Wegscheider, Andreas (CERN)
Publication	2024. - 5 p.
Imprint	5 p.
In:	JACoW HB 2023 (2024) 183-187
In:	68th ICFA Advanced Beam Dynamics workshop on high-Intensity and High-Brightness Hadron Beams (HB 2023), CERN, Geneva, Switzerland, 9 - 13 Oct 2023, pp.183-187
DOI	10.18429/JACoW-HB2023-TUC4C2
Subject category	Accelerators and Storage Rings
Abstract	With High Luminosity Large Hadron Collider (HL-LHC) beam intensities, there are concerns that the beam losses in the dispersion suppressors around the betatron cleaning insertion might exceed the quench limits. Furthermore, to maximize the beam lifetime it is important to reduce the impedance as much as possible. The collimators constitute one of the main sources of impedance in HL-LHC, given the need to operate with small collimator gaps. To improve this, a new optics was developed which increases the beta function in the collimation area, as well as the single pass dispersion from the primary collimators to the downstream shower absorbers. Other possible improvements from orbit bumps, to further enhance the locally generated dispersion, and from asymmetric collimator settings were also studied. The new solutions were partially tested with 6.8 TeV beams at the LHC in a dedicated machine experiment in 2022. In this paper, the new performance is reviewed and prospects for future operational deployment are discussed.
Copyright/License	© 2024 the author(s) (License: CC-BY-3.0)

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