Performance assessment after long-term irradiation of ATLAS Micromegas detectors using 120 GeV muons at the Gamma Irradiation Facility at CERN

The ATLAS muon spectrometer will face an increased particle rate as a result of the increased instantaneous luminosity expected during the High-Luminosity LHC (HL-LHC) upgrade. The HL-LHC will provide a luminosity of L = 7 . 5 × 1 0 34 cm − 2 s − 1 and 3000 fb − 1 of integrated luminosity in 10 years, about 9 times more data of the ones so far collected by the ATLAS experiment. Micromegas chambers are used in the New Small Wheel(s), the first forward muon spectrometer station, to provide tracking and triggering at the intense particle rates expected. The detectors are operated with a ternary gas mixture composed of Ar + 5 % CO 2 + 2 % iC 4 H 10 , providing good high voltage stability and a large pulse height, important for inclined track reconstruction of particles crossing the detector. To ensure the long-term stable operation of the detector during the whole HL-LHC period, and due to the hydrocarbon content in the mixture, an extensive aging campaign has been ongoing since 2021 at the CERN Gamma Irradiation Facility, where spare production chambers are long-term exposed to a 14 TBq 137 Cs γ -source, accumulating so far, a charge equivalent to five years of HL-LHC operations under the highest expected background rate. This paper describes the results of the Micromegas chamber performance studies after two years of gamma irradiation and using the SPS/H4 120 GeV muon beams at CERN.

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Journal
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
Published
2025-11-03
DOI
https://doi.org/10.1016/j.nima.2025.171137
Primary Topic
Particle Detector Development and Performance
Type
article
Field-Weighted Citation Impact
0.00

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article

Performance assessment after long-term irradiation of ATLAS Micromegas detectors using 120 GeV muons at the Gamma Irradiation Facility at CERN

S. Kompogiannis, A. Peyaud, I. Mesolongitis, Foteini Kolitsi et al.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
Particle Detector Development and Performance
article

Performance assessment after long-term irradiation of ATLAS Micromegas detectors using 120 GeV muons at the Gamma Irradiation Facility at CERN

S. Kompogiannis, A. Peyaud, I. Mesolongitis, Foteini Kolitsi, F. Vogel, V. D’Amico, P. Iengo, G. Iakovidis, Nikolaos Valantasis Kanellos, C. Kitsaki, F. Fallavollita, O. Biebel, G. Sekhniaidze, R. Hertenberger, T. Alexopoulos, P. Tzanis, Eshita Vinay Kumar
article en

Abstract

The ATLAS muon spectrometer will face an increased particle rate as a result of the increased instantaneous luminosity expected during the High-Luminosity LHC (HL-LHC) upgrade. The HL-LHC will provide a luminosity of L = 7 . 5 × 1 0 34 cm − 2 s − 1 and 3000 fb − 1 of integrated luminosity in 10 years, about 9 times more data of the ones so far collected by the ATLAS experiment. Micromegas chambers are used in the New Small Wheel(s), the first forward muon spectrometer station, to provide tracking and triggering at the intense particle rates expected. The detectors are operated with a ternary gas mixture composed of Ar + 5 % CO 2 + 2 % iC 4 H 10 , providing good high voltage stability and a large pulse height, important for inclined track reconstruction of particles crossing the detector. To ensure the long-term stable operation of the detector during the whole HL-LHC period, and due to the hydrocarbon content in the mixture, an extensive aging campaign has been ongoing since 2021 at the CERN Gamma Irradiation Facility, where spare production chambers are long-term exposed to a 14 TBq 137 Cs γ -source, accumulating so far, a charge equivalent to five years of HL-LHC operations under the highest expected background rate. This paper describes the results of the Micromegas chamber performance studies after two years of gamma irradiation and using the SPS/H4 120 GeV muon beams at CERN.

Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated EquipmentVol. 1083
National Technical University of Athens (GR), Johannes Gutenberg University Mainz (DE), Brookhaven National Laboratory (US), Aristotle University of Thessaloniki (GR), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR), Université Paris-Saclay (FR), University of West Attica (GR), Istituto Nazionale di Fisica Nucleare, Sezione di Napoli (IT), CEA Paris-Saclay (FR), Institut de Recherche sur les Lois Fondamentales de l'Univers (FR), Ludwig-Maximilians-Universität München (DE)
U.S. Department of Energy, CERN, Bundesministerium für Bildung und Forschung, National and Kapodistrian University of Athens, National Technical University of Athens, Office of Science, High Energy Physics
Openalex Percentile: Top 85%
Particle Detector Development and Performance
DOIOpen Access PDFOpenAlex
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