Speaker
Rajdeep Mohan Chatterjee
(University of Minnesota (US))
Description
Calorimetry at the High Luminosity LHC (HL-LHC) faces two enormous challenges, particularly in the forward direction: radiation tolerance and unprecedented in-time event pileup. To meet these challenges, the CMS experiment has decided to construct a High Granularity Calorimeter (HGCAL), featuring a previously unrealized transverse and longitudinal segmentation, for both electromagnetic and hadronic compartments. This will facilitate particle-flow-type calorimetry, where the fine structure of showers can be measured and used to enhance particle identification, energy resolution and pileup rejection. The majority of the HGCAL will be based on robust and cost-effective hexagonal silicon sensors with ~1cm^2 or 0.5cm^2 hexagonal cell size, with the final 5 interaction lengths of the hadronic compartment being based on highly segmented plastic scintillator with on-scintillator SiPM readout. A silicon-based 28-layer prototype using copper and tungsten as absorber materials (totalling 26 radiation lengths), has been constructed and tested in beams at FNAL. The prototype includes many of the features required for this challenging detector, including a complex PCB glued directly to the sensor, using through-hole wire-bonding for signal readout and ~5mm gaps between layers. The mechanics of the prototype allows these gaps to be varied, in order to study performance variations and therefore optimize the final detector design. Beams of electrons and pions up to 66 GeV have allowed measurements on basic calorimetric performance, including noise, calibration, energy linearity and resolution.
Primary author
Rajdeep Mohan Chatterjee
(University of Minnesota (US))
