Radiation dammage monitoring system of the fibers used in the CMS HF detector

HF detector is one of the sub-detectors of the CMS. HF which is designed as two hadron forward (HF±) calorimeters on both sides of the CMS interaction point (IP), at about ±11 m, covers the very forward angles of CMS, in the pseudorapidity range (3.0 < | ? | < 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 proximity of the proton beams are exposed to high radiation. This radiation causes deterioration of the fibers over the time. Some special channels are placed in the HF detector to observe the change due to radiation in the fibers. It is possible to monitor radiation damage online using the data taken from 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.