Commissioning and testing of pre-series triple GEM prototypes for CBM-MuCh in the mCBM experiment at the SIS18 facility of GSI

TL;DR

This paper reports on the design, installation, and testing of large-area triple GEM detectors for the CBM-MuCh system at FAIR, demonstrating their response and spatial correlation capabilities at high interaction rates.

Contribution

It presents the first commissioning and response analysis of full-size triple GEM modules in nucleus-nucleus collisions at FAIR, including event building based on timestamps.

Findings

Achieved a time resolution of approximately 15 ns for GEM detectors.

Observed clear spatial correlations between GEM modules in free-streaming data.

Demonstrated the detectors' capability to operate at high interaction rates up to 10 MHz.

Abstract

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 at 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.