HCal bar calibration with cosmics at LDMX

Sammanfattning

This thesis aims at understanding, through simulation, how the cosmic muon flux will look like in LDMX’s HCal and to use the characteristics of minimally ionizing muons to set up a method for scintillator bar calibration. LDMX’s HCal is a sampling calorimeter with scintillator bars as the active material. Cosmic muons enter the HCal from different angles, and thereby deposit different amounts of energy in the detector. This thesis implements a method for taking this directional dependence into account. A tracking algorithm is constructed that finds the straight path of a minimally ionizing particle; muons in this case. The algorithm is then used to estimate the energy deposited in a single bar, and is compared to the actual energy deposition. The ratio between estimated and actual energy in a bar is found to be 0.724 (0.233 MeV/mm vs 0.170 MeV/mm). This discrepancy requires further investigation. Based on the geometry of the back-HCal and a known muon flux, the back-HCal is found to be hit by 330,167 muons/min. With a requirement of every bar in the back-HCal having to register 1,000 hits each for calibration, and trigger selections for MIP-like events, it would take a runtime of 6,058 minutes, or 101 hours to collect the required dataset.