Modeling the triple-GEM detector response to background particles for the CMS Experiment

TL;DR

This paper presents a simulation framework combining FLUKA and Geant4 to accurately estimate background hit rates on triple-GEM detectors in the CMS experiment, validated against real data from LHC Run-2.

Contribution

The work introduces a novel integrated simulation approach for predicting detector background rates, aligning well with experimental measurements and aiding future high-luminosity collider planning.

Findings

Simulation agrees with data within 10-14.5% uncertainties.

The framework estimates background hit rates as a function of distance from the beam line.

Validated model can predict background rates for HL-LHC conditions.

Abstract

An estimate of environmental background hit rate on triple-GEM chambers is performed using Monte Carlo (MC) simulation and compared to data taken by test chambers installed in the CMS experiment (GE1/1) during Run-2 at the Large Hadron Collider (LHC). The hit rate is measured using data collected with proton-proton collisions at 13 TeV and a luminosity of 1.5$\times10^{34}$ cm$^{-2}$ s$^{-1}$. The simulation framework uses a combination of the FLUKA and Geant4 packages to obtain the hit rate. FLUKA provides the radiation environment around the GE1/1 chambers, which is comprised of the particle flux with momentum direction and energy spectra ranging from $10^{-11}$ to $10^{4}$ MeV for neutrons, $10^{-3}$ to $10^{4}$ MeV for $\gamma$'s, $10^{-2}$ to $10^{4}$ MeV for $e^{\pm}$, and $10^{-1}$ to $10^{4}$ MeV for charged hadrons. Geant4 provides an estimate of detector response (sensitivity) based on an accurate description of detector geometry, material composition and interaction of particles with the various detector layers. The MC simulated hit rate is estimated as a function of the perpendicular distance from the beam line and agrees with data within the assigned uncertainties of 10-14.5%. This simulation framework can be used to obtain a reliable estimate of background rates expected at the High Luminosity LHC.