Speaker
Description
Low-gain avalanche diodes (LGADs) will be employed in the CMS MIP Timing Detector (MTD) upgrade to mitigate the high levels of pileup expected in the High Luminosity phase of the LHC. Over the last several years, LGAD sensors with radiation tolerant gain implants have been developed, successfully providing gain even after the fluences expected at the HL-LHC, in excess of 1 x 10^15 neq/cm^2. However, it has been observed that highly-irradiated sensors operated at large bias voltage can be susceptible to single event burnout (SEB) when exposed to highly ionizing particles at beam tests. We present a series of measurements at the Fermilab Test Beam Facility to both understand the SEB mechanism and develop strategies for mitigation. We utilize a new, ultra-high rate beamline facility at FNAL to successfully operate irradiated LGAD sensors for a total flux comparable to the one year flux at the HL-LHC. We find that the SEB mechanism is mitigated by a slight reduction in bias voltage, with little to no impact on the CMS MTD performance.
