Studies with an Energy Weighting Method for the Upgrade of the Hadronic Barrel Calorimeter of CMS

CMS is one of the general purpose experiments of the Large Hadron Collider (LHC). The parameters of the particles released in proton-proton collisions will be measured there with high precision. The purpose of the hadronic calorimeter (HCAL) is mainly the determination of the energy of hadronic particles. It is a sampling calorimeter with an e/pi-ratio of about 1.2. For the CMS detector upgrade a longitudinal segmentation of the HCAL towers is planned, offering the possibility to resolve single parts of particle showers. This allows to establish a weighting method with the goal to distinguish between electromagnetic and hadronic energy depositions and thereby to improve its linearity and energy resolution by an adequate weighting. The weighting is based on the fact that the average energy density (energy per volume) of electromagnetic depositions is larger than for hadronic ones. Thus, the energy density is the criterion to estimate if an energy deposition is more electromagnetic-like or more hadronic-like. Here, studies of a method based on tabulated weighting factos are presented. Weighting factos as a function of the energy density have been obtained for simulated test beam data with several energies. These weighting factos are applied to simulated data to investigate the improvement of the linearity and energy resolution of the upgraded CMS barrel calorimeter. By this means, different readout designs can be examined to find the optimal configuration of the planned segmentation. The investigation of shower profiles and the fraction of electromagnetic and hadronic energy depositions helps to understand and to establish the method.