Speaker
Description
The endcap calorimeters of CMS will be upgraded a single High Granularity Calorimeter (HGCAL) for the HL-LHC. The HGCAL is a sampling calorimeter that will use silicon sensors as well as scintillator tiles as active material and be operated at -30 C. The silicon section will have several sensor thicknesses and there will be multiple sensor geometries based on 8" wafers. The readout of the sensors is performed by an ASIC (HGCROC) that measures the amplitude and timing of the signals. The amplitude is measured in a large dynamic range that needs to cover both single MIPs and TeV shower deposits and the timing precision for energetic deposits should be under 30 ps.
In the space of a few months in 2021, the HGCROCv3 was commissioned, assembled into a silicon module, and exposed to electron beams in the SPS H2 line. The module was operated for about a week in a chamber at 0 C and the signal from MIPs was seen for the first time even with the asynchronous nature of the beam. In this contribution we will present and discuss the experience of going from single HGCROCs from the foundry that did not work out of the box, all the way through to seeing MIP signals, including aspects of the Zynq-based readout system, the firmware developed to deal with the asynchronous beam timing, and the software that performed online monitoring using contemporary COTS technologies.
