Energy dependence of scintillation decay time measured with gamma-rays and compton electrons

The relation between non proportional response of the scintillators and their energy resolution has been extensively studied in the last years. However, there is not much data on the scintillation decay characteristics as a function of the energy deposited in the scintillator. This study presents a simple experimental setup for direct registration of the scintillation pulse shapes. The tested scintillators are coupled to a photomultiplier. Anode pulses are recorded directly by a digital oscilloscope. The scope is triggered by a logic signal from a single channel analyzer, employed to ensure precise selection of the energy deposit. The study is aimed at investigating the decay time constants and intensities of scintillation decay components as a function of the energy deposited in the scintillator. The differences in the pulse shapes generated in the Compton scattering and photoabsorption processes are also inspected. In this study we present the results of the test case study performed for NaI:TI scintillator.