Pulse Shape Discrimination in a Plastic Scintillator

A plastic scintillator has been developed which shows a decay time dependent upon energy loss per unit distance, and hence is suitable for use with pulse shape discrimination methods. This scintillator was employed in conjunction with an improved discrimination system and the data were analyzed on a two-dimensional analyzer which provided a matrix of 72 × 64 channels. At a bias level where 99 per cent of the electron scintillations were eliminated, it was possible to obtain almost 100 per cent counting efficiency for recoil protons of 2 mev, and the scintillator was useful for protons down to 0.5 mev. The influence of various monomers, polymerization conditions, scintillating solutes, and secondary solvents was investigated, and a preliminary survey of the effects of these variables on pulse shape discrimination is presented.