Speaker
Description
The CMS-HF Calorimeters are designed to detect the forward going particles at eta values from 3 to 5 with a high discovery potential for new phenomena. The HF calorimeters are sampling calorimeters with plastic cladded quartz fibers as active material and designed to survive at least through the first HL-LHC run period (Run 4) up to a cumulative 3000 fb-1 luminosity. Energy measurement of the calorimeters is based on the Cherenkov radiation in the fibers. Cherenkov light is transported to the PMTs by the same fibers. PMTs convert the light into charge and the total charge is used to determine the energy of the initial particle. Increasing attenuation in the fibers due to radiation damage will result in lower light intensity arriving at the PMTs and hence a lower total charge, causing the underestimation of the energy. It is important to monitor the radiation damage as a function of the luminosity to determine the correction factors for the calibration of the calorimeters. The upgraded radiation damage monitoring system has been commissioned at the end of Run 2 and in use since then. Radiation damage measurements at seven eta and four phi values as a function of the delivered luminosity will be presented for Run 3 along with the exponential fit results to the radiation damage data. Projections through 3000 fb-1 luminosity will be given and the future of the CMS-HF calorimeters will be discussed through HL-LHC Run 4 period.