Nov 22 – 25, 2021
Europe/Zurich timezone

UFO strategy (15' + 5')

Nov 25, 2021, 10:20 AM
500/1-001 - Main Auditorium (CERN)

500/1-001 - Main Auditorium


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Anton Lechner (CERN)


Dust particles interacting with the proton beams - commonly referred as UFOs - were the main source of transient beam losses in the past operation of the LHC. UFOs gave rise to 40 premature beam dumps and 8 dipole quenches in Run 2, resulting in the loss of more than 200 hours of beam time. The risk of dumps and quenches critically depends on the UFO event rate, which had significantly degraded after LS1. If a similar de-conditioning is observed after LS2, UFOs can have a relevant impact on the machine performance in 2022, in particular due to the reduced quench margin at 6.8 TeV and the higher shower-induced energy density in coils. This talk summarizes the present understanding of UFOs, the lessons learned from Run 2 and the increased risk of quenches at 6.8 TeV. Based on this input, UFO-related BLM threshold strategies for 2022 are discussed and expectations concerning dumps and quenches are presented. The talk also the outlines the impact of a possible 1-year extension of Run 3.

Presentation materials