Study of Radiation Damage in the CMS Hadron Calorimeter Using Isolated Muons from 2018 Collision Data

Isolated muons from proton-proton collision data, collected by the CMS detector at the LHC, are used to study radiation damage of different towers of the CMS hadron calorimeter. All the channels of the barrel and the endcap calorimeters in 2018 are read using hybrid photo diodes and Silicon photomultipliers, respectively. The data indicate that the barrel towers at larger pseudorapidity ($|\eta |$) show larger degradation in performance at the end of the run period. For endcap towers, the high level of pileup at the highest $|\eta |$ makes it difficult to determine the peak position of the charge distribution and is difficult to make any measurement. To make a measurement in the forward region of the detector, low pileup data collected by the CMS detector in 2018 are analyzed. The peak positions of the most affected towers are estimated with much better precision in these data. It is observed that several low luminosity runs distributed over the year can monitor the level of radiation damage in these most affected towers.