Aging and rate effects of the Multigap RPC studied at the gamma Irradiation Facility at CERN

Abstract The selected device for the ALICE Time-of-Flight array is the Multigap Resistive Plate Chamber (MRPC). Previously we have tested this device at the Gamma Irradiation Facility (GIF) at CERN to evaluate the rate dependence; we have now performed additional tests using the final design of the MRPC and with a gas mixture free of hydrocarbons. We have measured the performance of the MRPC up to an equivalent flux of minimum ionizing muons of 2.5 kHz/cm 2 . We also present results from an aging test obtained by exposing two MRPC strips to the GIF source for a period of six months.