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HK: Fachverband Physik der Hadronen und Kerne

HK 45: Instrumentation X

HK 45.5: Vortrag

Donnerstag, 30. März 2017, 15:00–15:15, F 072

The quality assurance scheme of GEM foils for the ALICE TPC upgrade — •Markus Ball, Viktor Ratza, Bernhard Ketzer, and Steffen Urban for the ALICE collaboration — Helmholtz Institut für Strahlen- und Kernphysik, Universität Bonn

With the planned upgrade of the ALICE (A Large Ion Collider Experiment at CERN) Time Projection Chamber the current readout technology will be replaced by a Gas Electron Multiplier (GEM) - based readout technology. This allows a continuous operation at high interaction rates up to 50kHz in Pb-Pb collisions. A stack of four GEM stages with specific field field configuration was chosen to achieve a suppression of the ion backflow below 1%, while maintaining a sufficient energy resolution below σ / E= 12% for ⁵⁵ Fe. The discharge probability was shown to be comparable to standard triple GEM detectors in low discharge settings.
To upgrade all the Inner and Outer Readout Chambers of ALICE, 576 GEM foils will be needed. However, taking into account a limited production yield, as well as, certain amounts of spare GEM foils, between 720 and 864 GEM foils will be produced and tested. Only GEM foils that fulfill the highest quality criteria can be used. Therefore, a stringent quality assurance (QA) scheme has been developed. The scheme includes leakage current measurements, high definition scanning of foil defects and gain uniformity measurements. A thourough documentation in a database allows to follow the QA history of each individual foil. This work is supported by BMBF.