Beam-induced backgrounds measured in the ATLAS detector during local gas injection into the LHC beam vacuum
Date
2024
Authors
Aad, G.
Aakvaag, E.
Abbott, B.
Abdelhameed, S.
Abeling, K.
Abicht, N.J.
Abidi, S.H.
Aboelela, M.
Aboulhorma, A.
Abramowicz, H.
Editors
Advisors
Journal Title
Journal ISSN
Volume Title
Type:
Journal article
Citation
Journal of Instrumentation, 2024; 19(06):P06014-1-P06014-59
Statement of Responsibility
The ATLAS collaboration
Conference Name
Abstract
Inelastic beam-gas collisions at the Large Hadron Collider (LHC), within a few hundred metres of the ATLAS experiment, are known to give the dominant contribution to beam backgrounds. These are monitored by ATLAS with a dedicated Beam Conditions Monitor (BCM) and with the rate of fake jets in the calorimeters. These two methods are complementary since the BCM probes backgrounds just around the beam pipe while fake jets are observed at radii of up to several metres. In order to quantify the correlation between the residual gas density in the LHC beam vacuum and the experimental backgrounds recorded by ATLAS, several dedicated tests were performed during LHCRun2. Local pressure bumps, with a gas density several orders of magnitude higher than during normal operation, were introduced at different locations. The changes of beam-related backgrounds, seen in ATLAS, are correlated with the local pressure variation. In addition the rates of beam-gas events are estimated from the pressure measurements and pressure bump profiles obtained from calculations. Using these rates, the efficiency of the ATLAS beam background monitors to detect beam-gas events is derived as a function of distance from the interaction point. These efficiencies and characteristic distributions of fake jets from the beam backgrounds are found to be in good agreement with results of beam-gas simulations performed with the Fluka Monte Carlo programme.
School/Discipline
Dissertation Note
Provenance
Description
Access Status
Rights
© 2024 CERN for the benefit of the ATLAS collaboration. Published by IOP Publishing Ltd on behalf of Sissa Medialab. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the https://doi.org/10.1088/1748-0221/19/06/P06014 2024 JINST 19 P06014 title of the work, journal citation and DOI.