Study of long-term performance of the triple-GEM detectors for future upgrade of the CMS muon high rate region at the HL-LHC.

Fallavollita F.

I - Fisica nucleare e subnucleare
Aula 32C-3 - Mercoledì 19 h 09:00 - 13:00
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In the framework of the High Luminosity LHC upgrade program, the new triple-Gas Electron Multiplier (GEM) detectors will be installed in the innermost region of the forward muon spectrometer of the CMS experiment in order to cope with the high-rate environment and maintain its actual performance. In the CMS muon system, based on gaseous detectors, the increase in luminosity will produce a particle background ten times higher than at the present LHC. The detailed knowledge of the detector performance at such high background is crucial for optimized design and efficient operation after the HL-LHC. A precise understanding of possible aging effects of detector materials and gases is of extreme importance. For this reason, aging tests of a full-sized triple-GEM detector operated with an $Ar/CO_{2}$ (70:30) gas mixture at an effective gas gain of $2 \times 10^{4}$, are ongoing at the CERN Gamma Irradiation Facility (GIF++). The detector is irradiated with 662 keV gamma-rays from a 14 TBq ${}^{137}$Cs source. In parallel, a second similar detector is irradiated in the CMS-GEM QA/QC lab using a 22 keV X-ray source. We will describe the performance of triple-GEM detectors during the irradiation tests up to an overall aging of 10 CMS equivalent years corresponding to an integrated charge of 0.85 C/cm${}^{2}$, which includes a safety factor of three compared to the HL-LHC conditions.

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