Münster 2017 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 52: HK+T Joint Session VII: Gas Detectors/GEM

HK 52.5: Talk

Thursday, March 30, 2017, 18:00–18:15, F 102

Study of single-mask GEM foil performance for the upgrade of the ALICE TPC — •Hendrik Schulte, Esther Bartsch, Rainer Renfordt, and Harald Appelshäuser for the ALICE collaboration — Institut für Kernphysik, Goethe-Universität Frankfurt

In the LHC Run 3 period the interaction rate of Pb-Pb collisions will be increased to 50 kHz. To accomodate the higher rates the Time Projection Chamber (TPC) of ALICE has to be upgraded. In this upgrade the Multiwire Proportional Chambers of the TPC’s readout system will be replaced by quadruple Gas Electron Multiplier (GEM) stacks that can be operated in continuous mode. However, to prevent space-charge distortions in the drift volume the backflow of positive ions has to be kept below 1%. At the same time a reasonable energy resolution has to be maintained to preserve the good particle identification capability of the TPC.

So far GEMs have been produced in two different ways. While the GEM foils used in previous tests were produced with the so-called double-mask technique, the GEMs for the final readout chambers will be mass-produced with the so-called single-mask technique.

A dedicated test detector for the characterization of quadruple GEM stacks was set up at the IKF in Frankfurt. The performance of single-mask GEM foils for different voltage settings, also in comparison with double-mask GEM foils, will be presented.

Supported by BMBF and the Helmholtz Association.