Characterization and energy calibration of a Cerium-doped LaBr3 gamma ray detector using Geant4 simulations

Cerium-doped Lanthanum(III) bromide detectors are new inorganic crystal scintillation detectors being tested and utilized at CERN's Neutron Time of Flight (n_ToF) facility for gamma-ray detection as a potential candidate for inelastic (n,n'g) reactions cross section measurements. Before performing experimentation at n_ToF using these new 2.5x2.5cm LaBr3(Ce) detectors, a characterization is necessary for understanding their energy resolution and detection efficiency at different distances. By placing a radioactive source in front of a newly acquired LaBr3(Ce) detector coupled to a PMT with a voltage divider, a greater understanding of the detector's abilities can be achieved. A calibration was conducted using a 152Eu source at distances ranging from 7.5cm to 17.5cm away from a LaBr3(Ce) detector for the purpose of observing the detector's efficiency at varying distances, including those expected to be used in later in-beam experiments. The resulting gamma ray spectrum data yields efficiencies of approximately 0.3% and 0.04% at 121.8 keV and 964.1 keV respectively. These results will be observed in comparison to Geant4 simulations adapted from the existing Geant4 rdecay02 example.