Radiation Damage Monitoring System of The CMS HF Detector

Abstract

Hadronic Forward(HF) detector is one of the sub-detectors of the CMS. It plays an important role in the measurement of forward jets and missing energy. HF is situated on both sides of the CMS interaction point, at about $\pm$11 m, covers the very forward angles of CMS, in the pseudorapidity range (3.0 < | $\eta$ | < 5.0), leaving only clearance for the beam pipes. This calorimeter consists of quartz fibers embedded in the iron absorber. Cherenkov light created by the charged particles is transmitted to PMTs by the fibers. Fibers due to the proton-proton collisions are exposed to high radiation. This radiation causes deterioration of the fibers over the time. Special channels are placed in the HF detector to observe the changes in the fibers due to radiation. It is possible to monitor radiation damage online using the data taken for these channels. In this study, radiation damage of HF is analyzed using the local data which was taken during 2010 run period. A number of innovations and modifications have been proposed for the analysis method.