Characteristics of triple GEM detector have been studied systematically. The variation of the effective gain and energy resolution of GEM with variation of the applied voltage has been measured with Fe55 X-ray source for different gas mixtures and with different gas flow rates. Long-term test of the GEM has also been performed.
In CBM Experiment at FAIR, dimuons will be detected by a Muon Chamber (MUCH) consisting of segmented absorbers of varying widths and tracking chambers sandwiched between the absorber-pairs. In this fixed target heavy-ion collision experiment, operati
ng at highest interaction rate of $10~MHz$ for $Au+Au$ collision, after the first MUCH detector station in its inner radial ring will face a particle rate of $1~MHz/cm^2$. To operate at such a high particle density, GEM technology based detectors have been selected for the first two stations of MUCH. We have reported earlier the performance of several small-size GEM detector prototypes built at VECC for use in MUCH. In this work, we report on a large GEM chamber prototype tested with proton beam of momentum $2.36~GeV/c$ at COSY-J{u}elich Germany. The detector was read out using nXYTER ASIC operated in self-triggering mode. An efficiency higher than $96%$ at $Delta V_{GEM}~=~375.2~V$ was achieved. The variation of efficiency with the rate of incoming protons has been found to vary within $2%$ when tested up to a maximum rate of $2.8~MHz/cm^2$. The gain was found to be stable at high particle rate with a maximum variation of $sim~9%$.
The Compressed Baryonic Matter~(CBM) experiment in the upcoming Facility for Antiproton and Ion Research~(FAIR), designed to take data in nuclear collisions at very high interaction rates of up to 10 MHz, will employ a free-streaming data acquisition
with self-triggered readout electronics, without any hardware trigger. A simulation framework with a realistic digitization of the detectors in the muon chamber (MuCh) subsystem in CBM has been developed to provide a realistic simulation of the time-stamped data stream. In this article, we describe the implementation of the free-streaming detector simulation and the basic data related effects on the detector with respect to the interaction rate.
Large area triple GEM chambers will be employed in the first two stations of the MuCh system of the CBM experiment at the upcoming Facility for Antiproton and Ion Research FAIR in Darmstadt/Germany. The GEM detectors have been designed to take data a
t an unprecedented interaction rate (up to 10 MHz) in nucleus-nucleus collisions in CBM at FAIR. Real-size trapezoidal modules have been installed in the mCBM experiment and tested in nucleus-nucleus collisions at the SIS18 beamline of GSI as a part of the FAIR Phase-0 program. In this report, we discuss the design, installation, commissioning, and response of these GEM modules in detail. The response has been studied using the free-streaming readout electronics designed for the CBM-MuCh and CBM-STS detector system. In free-streaming data, the first attempt on an event building based on the timestamps of hits has been carried out, resulting in the observation of clear spatial correlations between the GEM modules in the mCBM setup for the first time. Accordingly, a time resolution of $sim$15,ns have been obtained for the GEM detectors.
The stability of triple GEM detector setups in an environment of high energetic showers is studied. To this end the spark probability in a shower environment is compared to the spark probability in a pion beam.
The Compressed Baryonic Matter spectrometer (CBM) is a future fixed-target heavy-ion experiment located at the Facility for Anti-proton and Ion Research (FAIR) in Darmstadt, Germany. The key element in CBM providing hadron identification at incident
beam energies between 2 and 11 AGeV (for Au-nuclei) will be a 120 m$^2$ large Time-of-Flight (ToF) wall composed of Multi-gap Resistive Plate Chambers (MRPC) with a system time resolution better than 80 ps. Aiming for an interaction rate of 10 MHz for Au+Au collisions the MRPCs have to cope with an incident particle flux between 0.1~kHz/cm$^2$ and 100~kHz/cm$^2$ depending on their location. Characterized by granularity and rate capability the actual conceptual design of the ToF-wall foresees 6 different counter granularities and 4 different counter designs. In order to elaborate the final MRPC design of these counters several heavy-ion in-beam and cosmic tests were performed. In this contribution we present the conceptual design of the TOF wall and in particular discuss performance results of full-size MRPC prototypes.