Evaluation of the capability of coumarin dye as a liquid scintillator for gamma ray detection and compton edge localization

In this work, we developed a highly sensitive liquid scintillator (LS) using Coumarin 450 (C450) dye to detect gamma ray and localize Compton edges (CEs). C450 exhibited absorption and fluorescence peaks at 350 nm and 407 nm, respectively, in toluene, at an optimized concentration (3 mM). The LS, contained in a standard glass container (1.8 cm diameter, 3.6 cm height), showed an emission peak in the blue region, matching the high quantum yield of typical PMT photocathodes. We exposed the LS to various gamma radiation sources (137Cs, 60Co, and 22Na), recording responses for different PMT voltages. Gaussian fitting of pulse height distribution spectrum allowed CE identification at the half-height for all PMT voltages. We compared theoretical and experimental results to a GEANT4-simulated detector, obtaining CE positions for radiation interactions and scintillation photon transport. The calibrated GEANT4 simulation was compared to experimental spectra to locate the Compton edges.