Performance studies under high irradiation and ageing properties of resistive bulk Micromegas chambers at the new CERN Gamma Irradiation Facility

•Small-size resistive bulk Micromegas detectors have been exposed to the new GIF++.•9 months irradiation to γ up to 20 Mhz/cm2. 0.09 C/cm2 collected integrated charge.•Νo degradation of the detector performance was observed.•Muon tracks successfully reconstructed up to 68 kHz/cm2 gamma background.•Higher background rates will be studied in the coming months.

Resistive bulk Micromegas chambers, produced at CERN, have been installed at the new CERN Gamma Irradiation Facility (GIF++) in order to study the effects of ageing and to evaluate the detector behaviour under high irradiation. The chambers have an active area of 10×10 cm2, strip pitch of 400 μm and an amplification gap of 128 μm. We present the detector performance as a function of the background rate of up to 20 MHz/cm2.