Karlsruhe 2024 – scientific programme
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T: Fachverband Teilchenphysik
T 64: Detectors 7 (gas detectors)
T 64.1: Talk
Wednesday, March 6, 2024, 16:00–16:15, Geb. 30.23: 2/17
Test of ATLAS Micromegas detectors with a ternary gas mixture at the CERN GIF++ facility — •Fabian Vogel, Otmar Biebel, Valerio D’Amico, Stefanie Götz, Ralf Hertenberger, Roman Lorenz, Eshita Kumar, Katrin Penski, Nick Schneider, and Chrysostomos Valderanis — LMU München
The ATLAS collaboration at LHC has chosen the resistive Micromegas technology, along with the small-strip Thin Gap Chambers (sTGC), for the high luminosity upgrade of the first muon station in the high-rapidity region, the New Small Wheel (NSW) project. Achieving the requirements for these Micromegas detectors revealed to be even more challenging than expected. One of the main features being studied is the HV stability of the detectors. Several approaches have been tested in order to enhance the stability, among them the use of different gas mixtures. A ternary Argon-CO2-iC4H10 mixture has shown to be effective in dumping discharges and dark currents. It allows the operation of the Micromegas detectors at safe working points with high cosmic muon detection efficiency. The presence of Isobutane in the mixture required a set of aging studies, ongoing at the GIF++ radiation facility at CERN, where the expected HL-LHC background rate is created by a 137Cs 14 TBq source of 662 keV photons. Preliminary aging results and muon reconstruction efficiencies under photon background of the ternary mixture will be shown.
Keywords: ATLAS, Micromegas, Isobutane, Longevity