Münster 2017 – scientific programme
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T: Fachverband Teilchenphysik
T 92: Strahlenschäden (gemeinsam mit HK)
T 92.7: Talk
Wednesday, March 29, 2017, 18:15–18:30, F 234
Study of GEM ageing effects for the ALICE TPC Upgrade — •Michael Jung1, Harald Appelshäuser1, Chilo Garabados2, and Renato Negrao de Oliveira3 for the ALICE collaboration — 1IKF - Goethe-Universistät Frankfurt — 2GSI - Helmholtzzentrum für Schwerionenforschung — 3Universidade de Sao Paulo
Long-term measurements with a quadruple stack of Gas Electron Multipliers (GEMs) at relatively high gain (about 15,000) were performed to invesitgate the ageing effects of GEMs in Ar-CO2 (70-30). The GEM stack was irradiated with a high-rate 55Fe source to simulate the dose of the upgraded ALICE Time Projection Chamber (TPC) at the LHC during RUN3 with a Pb–Pb interaction rate of about
50 kHz. Also the outgassing effects of different materials, such as Vetronite, Araldite 2011 and Polyamide on the energy resolution and the gain were studied. During all measurements the temperature and the ambient pressure were measured to discriminate between a change of the environment conditions and a degradation of the detector properties. One phenomenon observed was that the kapton in the GEM holes was etched, so that the double conical shape of the holes got lost.