Irradiation tests of the OBDTv1 board at CHARM

The CMS Muon Drift Tube (DT) chambers require an upgrade of their on-detector electronics for operation in the High Luminosity LHC (HL-LHC) due to increased radiation, occupancy and trigger rates. The new On-Detector Board for Drift Tubes (OBDT) digitizes drift signals with a resolution of 0.8 ns and transmits them via high-speed optical links into the counting room, where the full detector information will be available to perform the trigger and event building logic. The prototype, OBDTv1, featuring a Microsemi PolarFire FPGA, underwent radiation testing at CERN's CHARM facility to validate its resilience in a full system test. Results confirmed the FPGA's robustness and also confirmed that the cross-sections obtained are comparable in reference tests and for the full final firmware. Few manageable Single Event Upsets (SEU) translate into rates below 0.24 SEUs/day in the full detector during operation at HL-LHC, ensuring reliable data acquisition. Resilient performance of all of the other components from the OBDTv1 board was also confirmed. The final OBDT will replace GBTx with lpGBT for enhanced speed and will use VTRX+ as optical transceivers, all of them radiation tolerant. Therefore, the results presented here demonstrate the readiness of the OBDT design for HL-LHC deployment.