Laser system studies in hadronic calorimeter of CMS

CMS which is one of the four biggest experiments in the LHC, investigates the production yields from the proton–proton collisions. As one of the sub-detectors of CMS, Hadronic Calorimeter(HCAL) measures the energy and position of the quarks and gluons which are created in the proton-proton collisions. Some unexpected high energies were seen in some channels of the HB which is one of the subcalorimeters of HCAL, at 7 TeV collisions from the LHC in 2012. It was determined that, these unexpected high energies originated from the laser system, and it was thought that these unexpected laser signals exist at some channels of HB although the laser system was off. CMS laser calibration system were used to check radiation damage of detectors, linearity of QIE cards, stability of energy measurement and performance of the calorimeters. In this study some filtering study was done for these unexpected laser signals although the laser system was off and also all studies were repeated for 2015 data, in which the new laser system was installed.