Development of Tracking Detectors with industrially produced GEM Foils

Abstract

The planned tracking upgrade of the STAR experiment at RHIC includes a large-area GEM tracker used to determine the charge sign of electrons and positrons produced from W +(−) decays. For such a large-scale project commercial availability of GEM foils is necessary. We report first results obtained with a triple GEM detector using GEM foils produced by Tech-Etch Inc. of Plymouth, MA, USA. Measurements of gain uniformity, long-term stability as well as measurements of the energy resolution for X-Rays are compared to results obtained with an identical detector using GEM foils produced at CERN. A quality assurance procedure based on optical tests using an automated high-resolution scanner has been established, allowing a study of the correlation of the observed behavior of the detector and the geometrical properties of the GEM foils. Detectors based on Tech-Etch and CERN produced foils both show good uniformity of the gain over the active area and stable gain after an initial charge-up period, making them well suited for precision tracking applications.

Demonstration of new possibilities of multilayer technology on resistive microstrip/microdot detectors

“…variation. In these measurements 710V was applied to the anode and -300V to the internal Note that this value obtained of 5% is quite good if compared to the stability vs. the time observed at various conditions with GEM or TGEM [10][11][12].…”

“…The first effect is well known and was observed both with GEMs and TGEMs [10][11][12]. The simplest solution is to keep a constant high voltage applied to the detector [13].…”

X-Ray fluorescence imaging system based on Thick-GEM detectors

“…It is known from several sources, such as, for example [79,80,81], that the gain across a GEM's active area is not uniform and this deviation is linked with factors that may change the electric field configuration such as small differences in the drift, transfer and induction regions widths, local charge accumulation in the GEM surfaces (charge-up) and deviations in the size of the holes in the GEM. Therefore, another correction in the off line data processing was included, using a map of the gain variations across the detector.…”