A RATIO PULSE-SHAPE DISCRIMINATOR

A simple pulse-shape discriminator has been designed to separate signa ls from a CsI(Na)/GSO phoswich detector. It Can provide information on both the total energy deposited and the contribution of each crystal to that total, allowing a software veto to be used according to the di stribution of the energy deposited. Test results show that even for ph otons having an energy of 17 keV, the location of most of the interact ions can be found unambiguously. The system has also been tested on th e most commonly used NaI(Tl)/CsI(Tl) phoswich detector without particu lar optimisation of the shaping time-constants. These results show tha t it can work well for gamma-rays below 17 keV. This technique could b e very useful in a system which produces more than two decay component s, such as a triple phoswich detector, or in a system where pulse-shap e discrimination is used for particle identification.