Radiation damage measurement of plastic scintillators with silicon photomultipliers using collision data in the CMS hadronic calorimeter experiment

Abstract

In high energy particle collisions, plastic scintillators are commonly used to detect secondary particles and measure their energy along with silicon photomultipliers to amplify the signal. These detectors deteriorate over time due to irradiation they are exposed to and lose their capacity to detect particles efficiently. In the Compact Muon Experiment (CMS) experiment at CERN, hadronic calorimeter is equipped with passive absorbers, plastics scintillators and silicon photomultipliers. In 2017 and 2018, in the data taking periods, in Large Hadron Collider (LHC) two proton beams traveling at opposite directions at energies 6.5TeV are collided and outgoing particles are detected at two detector locations (CMS and ATLAS) along the accelerating ring. In the CMS experiment, energy response obtained from plastic scintillators are monitored in hadronic endcap calorimeter throughout the year and signal drop is measured with collision data, a method also known as in-situ measurement. Energy response of the detector can be monitored with precision in cellular level in longitudinal and azimuthal directions. Signal drop is compared with the results obtained by alternative methods such as laser method. These results not only give insights about the life time of plastic scintillators and silicon photomultipliers but also show their response to dose and dose rate effects. They also provide prospects for future upgrades. The results are used to calibrate the energy values of the collision events for precision measurements and are an integral part of the experiment. We provide the full results of our analysis.