Abstract
The High Luminosity LHC (HL-LHC) will integrate 10 times more luminosity than the LHC, posing significant challenges for radiation tolerance and event pileup on detectors, especially for forward calorimetry, and hallmarks the issue for future colliders. As part of its HL-LHC upgrade program, the CMS Collaboration is designing a High Granularity Calorimeter (HGCAL) to replace the existing endcap calorimeters. It features unprecedented transverse and longitudinal segmentation for both electromagnetic (CE-E) and hadronic (CE-H) compartments. This will facilitate particle-flow (PF) calorimetry, where the fine structure of showers can be measured and used to enhance pileup rejection and particle identification, whilst still achieving good energy resolution. The CE-E and a large fraction of CE-H will be based on hexagonal silicon sensors of [Formula: see text] cell size, with the remainder of the CE-H based on highly-segmented scintillators with SiPM readout. The intrinsic high-precision timing capabilities of the silicon sensors will add an extra dimension to event reconstruction, especially in terms of pileup rejection. An overview of the HGCAL project is presented in this paper.
Highlights
To sustain and extend its discovery potential, the LHC will undergo a major upgrade by ∼ 2026, relying on key innovations that push accelerator technology beyond its present limits
Major challenges in the HL-LHC era are related to the average number of expected primary vertices in a single bunch crossing (BX), that will rise up to ∼ 200, and by the harsh radiation environment due to the huge particle flux
The CMS Phase-II Endcap Calorimeter upgrade As part of the Phase-II upgrade[1], the CMS Collaboration envisages the complete replacement of the endcap calorimeters with the High Granularity Calorimeter (HGCAL) detector, a high granular silicon (Si) and scintillator-based sampling calorimeter capable of sustaining the high fluence
Summary
To sustain and extend its discovery potential, the LHC will undergo a major upgrade by ∼ 2026, relying on key innovations that push accelerator technology beyond its present limits. Major challenges in the HL-LHC era are related to the average number of expected primary vertices in a single bunch crossing (BX), that will rise up to ∼ 200, and by the harsh radiation environment due to the huge particle flux This will imply unprecedented difficulties in the identification of the hard scattering vertices and in object reconstruction that will become even more difficult over the lifetime of the HL-LHC. The absorber in the hadronic section (CE-H) consists of 12 layers of 35 mm thick SS plates followed by another 12 SS layers with a thickness of 68 mm In between these absorber plates sit Si-modules and scintillator tileboards mounted on 6 mm thick Cu cooling plates to form 30◦ wide cassettes. Each sensor has either 192 or 432 individual cells, for 1.05 and 0.56 cm[2] cells respectively
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