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Description
The CMS detector is set to be upgraded for the HL-LHC proton collider at CERN with the addition of a MIP Timing Detector (MTD). The MTD will feature barrel and endcap timing layers, BTL and ETL, to enable precise timing measurements of charged particles. The BTL sensors utilize LYSO:Ce scintillation crystals coupled with SiPMs and TOFHIR2 ASICs for front-end readout. Over the HL-LHC's lifetime, the system is expected to achieve a timing resolution of 30-60 ps for MIP signals at a rate of 2.5 Mhit/s per channel. During its operation, the detector is exposed to a large flux of particles. In consequence, the TOFHIR2 chip must be resistant to the expected total ionization dose TID (29 kGray) and to the integrated particle fluence (2×1014 neq/cm2) in the BTL.
In this paper, we present an overview of the TOFHIR2 requirements and design, and of the measurements performed with TOFHIR2 ASICs with emphasis on the radiation resistance. The measurements of TOFHIR2 associated to sensor modules were performed in different test setups using internal test pulses or blue and UV laser pulses emulating the signals expected in the experiment. Extensive radiation tests, including x-rays and heavy ions, confirmed that TOFHIR2 remains unaffected by the radiation environment throughout the experiment's lifetime.
