Performance of the CMS High Granularity Calorimeter prototype to charged pion beams of 20$-$300 GeV/c

TL;DR

This paper evaluates the performance of a prototype high granularity calorimeter for the CMS experiment using charged pion beams at CERN, demonstrating its energy response, resolution, and shower profiles in comparison with simulations.

Contribution

First report on hadronic shower measurements of the CMS HGCAL prototype using beam test data, validating its design and simulation models.

Findings

Calorimeter shows good energy response and resolution for charged pions.

Measured shower profiles agree with GEANT4 simulations.

Demonstrates the feasibility of high granularity calorimetry for future collider experiments.

Abstract

The upgrade of the CMS experiment for the high luminosity operation of the LHC comprises the replacement of the current endcap calorimeter by a high granularity sampling calorimeter (HGCAL). The electromagnetic section of the HGCAL is based on silicon sensors interspersed between lead and copper (or copper tungsten) absorbers. The hadronic section uses layers of stainless steel as an absorbing medium and silicon sensors as an active medium in the regions of high radiation exposure, and scintillator tiles directly readout by silicon photomultipliers in the remaining regions. As part of the development of the detector and its readout electronic components, a section of a silicon-based HGCAL prototype detector along with a section of the CALICE AHCAL prototype was exposed to muons, electrons and charged pions in beam test experiments at the H2 beamline at the CERN SPS in October 2018. The AHCAL uses the same technology as foreseen for the HGCAL but with much finer longitudinal segmentation. The performance of the calorimeters in terms of energy response and resolution, longitudinal and transverse shower profiles is studied using negatively charged pions, and is compared to GEANT4 predictions. This is the first report summarizing results of hadronic showers measured by the HGCAL prototype using beam test data.