Pulse Shape Discrimination in Polysiloxane-Based Liquid Scintillator

The time response of a recently developed polysiloxane based liquid scintillator has been analyzed for the first time: a special focus on the pulse shape discrimination capability of this material, which is characterized by low toxicity and low volatility, has been addressed. Fluorescence lifetime and scintillation pulses have been studied at different primary dye concentrations, with the aim of optimizing the neutron/gamma discrimination, connecting the results to the energy transfer and to the formation of excimers inside the scintillating solution. Pulse shape analysis performed during the irradiation of the samples with a pulsed neutron beam allowed the definition of a figure of merit as an indicative parameter for the neutron/gamma discrimination. The dependence of this parameter from radiation energy and PPO concentration has been analyzed in order to optimize the performances of the material in view of its possible use in environments with high gamma-ray radiation background.