Speaker
Description
The High Luminosity era of the LHC will present significant challenges for event reconstruction due to up to 200 proton-proton collisions per bunch crossing. To address these intense pileup effects, the CMS experiment is undergoing an extensive upgrade, which includes the integration of a new timing layer: the MIP Timing Detector (MTD). The MTD is designed to enable 4D vertexing by providing a time measurement for charged particles with a projected resolution of 30–60 ps. This is expected to substantially improve track-to-vertex association and object identification. The MTD comprises two distinct subsystems: Barrel Timing Layer (BTL) and the Endcap Timing Layer (ETL), which is the focus of this talk. The ETL uses low-gain avalanche diodes (LGADs) with 50 μm active thickness read out by a custom-designed ASIC in 65 nm CMOS (ETROC) to provide timestamps for charged particles in the pseudorapidity region 1.6 < η < 3. The pixel array on a single chip is 16x16 pixels, with each pixel measuring 1.3 mm x 1.3 mm. The fundamental unit of the ETL is hence defined by a single ETROC chip (21 mm x 23 mm) bump-bonded to an LGAD sensor array, forming an ETL hybrid. The ETROC2 is the first full-size, full-functionality prototype of the ETROC ASIC. Over the past 3 years, the characterization campaign for the ETROC2 and the corresponding hybrids has been successfully completed, including in a mini-system like environment with lpGBT and VTRX+ readout, validating the expected performance in the ETL. In this talk, we present three sets of new results: the performance of ETROC2 hybrids irradiated up to the expected end of life fluence at CERN IRRAD, the dependence of hybrid performance on particle incident angle, and wafer-level yield results from full-functionality testing of the final ETROC2a version conducted this year.