Performance of a large size triple GEM detector at high particle rate for CBM Experiment at FAIR

摘要

In CBM Experiment at FAIR, dimuons will be detected by a Muon Chamber (MUCH)consisting of segmented absorbers of varying widths and tracking chamberssandwiched between the absorber-pairs. In this fixed target heavy-ion collisionexperiment, operating at highest interaction rate of $10~MHz$ for $Au+Au$collision, after the first MUCH detector station in its inner radial ring willface a particle rate of $1~MHz/cm^2$. To operate at such a high particledensity, GEM technology based detectors have been selected for the first twostations of MUCH. We have reported earlier the performance of severalsmall-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 usingnXYTER ASIC operated in self-triggering mode. An efficiency higher than $96\%$at $\Delta V_{GEM}~=~375.2~V$ was achieved. The variation of efficiency withthe rate of incoming protons has been found to vary within $2\%$ when tested upto a maximum rate of $2.8~MHz/cm^2$. The gain was found to be stable at highparticle rate with a maximum variation of $\sim~9\%$.