Surface Commissioning and Performance of the sMDT Muon Chambers for the ATLAS HL-LHC Upgrade

@misc{ge2026surface,
  title = {{Surface Commissioning and Performance of the sMDT Muon Chambers for the ATLAS HL-LHC Upgrade}},
  author = {Jiajin Ge and Elena Voevodina and Hubert Kroha and Tatiana Azaryan and Kwok Ching Cheung and Tiesheng Dai and Edward Diehl and Claudio Ferretti and Yuxiang Guo and Oliver Kortner and Chihao Li and Chun Kit Lo and Nick Meier and Emmett Salzer and Can Suslu and Cecilia Vanesa Imthurn and Samuel Hugo Venetianer and Curtis Weaverdyck and Chuanshun Wei and Bastian Michael Wesely and Ruslan Yakubovych and Bing Zhou and Junjie Zhu and Jörg Zimmermann},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.12799},
  eprint = {2609.12799},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.12799},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - Surface Commissioning and Performance of the sMDT Muon Chambers for the ATLAS HL-LHC Upgrade
AU  - Jiajin Ge
AU  - Elena Voevodina
AU  - Hubert Kroha
AU  - Tatiana Azaryan
AU  - Kwok Ching Cheung
AU  - Tiesheng Dai
AU  - Edward Diehl
AU  - Claudio Ferretti
AU  - Yuxiang Guo
AU  - Oliver Kortner
AU  - Chihao Li
AU  - Chun Kit Lo
AU  - Nick Meier
AU  - Emmett Salzer
AU  - Can Suslu
AU  - Cecilia Vanesa Imthurn
AU  - Samuel Hugo Venetianer
AU  - Curtis Weaverdyck
AU  - Chuanshun Wei
AU  - Bastian Michael Wesely
AU  - Ruslan Yakubovych
AU  - Bing Zhou
AU  - Junjie Zhu
AU  - Jörg Zimmermann
PY  - 2026
DA  - 2026/09/11
PB  - arXiv
DO  - 10.48550/arxiv.2609.12799
UR  - https://arxiv.org/abs/2609.12799
AB  - To improve the first-level muon trigger efficiency at the HL-LHC, the Monitored Drift Tube (MDT) chambers in the inner small sectors of the ATLAS Barrel Muon Spectrometer will be replaced with integrated modules of small-Diameter Muon Drift Tube (sMDT) and Resistive Plate Chambers (RPCs). This paper reports on the surface commissioning of 102 new sMDT chambers at CERN in 2025 following the installation of the final front-end electronics, including the new Amplifier-Shaper-Discriminator (ASD), Time-to-Digital Converter (TDC) chips, and Chamber Service Module (CSM) developed for the HL-LHC. The commissioning included measurements of gas leak rates and high-voltage dark currents, tests of the integrated planarity monitoring system, noise characterization, and measurements of detector efficiency and spatial resolution using cosmic rays. Fewer than 0.1\% of the 49152 tubes were found to be non-functional due to broken sense wires or gas leaks. The chambers exceed the ATLAS design requirements, with gas leak rates a factor of five below the specified limit of 9.3× 10^−3 mbar· liter/s per chamber, dark currents of only around 0.2~nA per tube, average channel noise hit rates below 30~Hz, and average drift tube efficiency and spatial resolution of 99\% and 82 μm, respectively, at an effective threshold of 15 primary electrons.
ER  -