Bochum 2018 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 52: Poster

HK 52.32: Poster

Thursday, March 1, 2018, 16:30–18:45, Audimax Foyer

A Spark-Detection-System for GEM foils — •Philip Hauer, Steffen Urban, Viktor Ratza, Markus Ball, and Bernhard Ketzer for the ALICE collaboration — Universität Bonn, Helmholtz-Institut für Strahlen- und Kernphysik, Bonn, Germany

Gas Electron Multipliers (GEM) are widely used as an amplification stage in gaseous detectors exposed to high rates. The GEM consists of a polyimide foil which is coated by two thin copper layers. GEM have a high density of holes, where charges are multiplied if suitable voltages are applied. One example where GEM foils will be used is the Time Projection Chamber (TPC) of ALICE (A Large Ion Collider Experiment) after its upgrade which will take place during the long shutdown 2 of the Large Hadron Collider (LHC). Over 700 GEM foils will be manufactured for the read-out chambers, each with a size of several hundred square centimeters. In order to assure the quality of each individual GEM foil, a strict quality-control protocol is followed. One important step in this protocol is the leakage-current measurement. For this measurement, a voltage of 500 V is applied on a GEM foil for 15 minutes and the current is measured with a pA-meter. While the high voltage is applied, it is possible that discharges occur in one or more holes of the GEM. Until now, these sparks can only be measured by eye which is cumbersome and not precise. With the help of the Spark-Detection-System (SDS), the detection is automized and accuracate to approximately 1 mm. A camera observes the GEM during the measurement and the video stream is analyzed by a LabView software. Supported by BMBF.