High Energy Physics Seminars

The CMS experiment at CERN will be significantly upgraded during Long Shutdown 3 of the LHC (2026-2028) to operate with a 10-fold increase in luminosity and the associated event pileup of 140-200 proton-proton interactions per bunch crossing of the High-Luminosity LHC (HL-LHC).  The endcap calorimeter region, covering 1.5 < |η| < 3.0, will be exposed to very high radiation levels and to mitigate this, a new calorimeter, the High Granularity Calorimeter (CE), will replace the existing endcap calorimeter.  It will have higher transverse and longitudinal segmentation for both electromagnetic (CE-E) and hadronic (CE-H) sections to facilitate particle-flow reconstruction.  The fine structure of showers can be measured and used to enhance particle identification, whilst still achieving good energy resolution.  The CE-E, and a large fraction of CE-H, will use hexagonal silicon sensors produced from 8-inch wafers as active material, each with several hundreds of individual cells of 0.5-1 sq. cm cell size.  The remainder of the CE-H will use highly-segmented scintillators read out with SiPMs as active material.  An overview of the CE project, including motivation, design, timeline, and expected performance, will be presented in this talk together with a deeper look at the silicon sensor design and performance status on the eve of pre-production.