A ratio pulse-shape discriminator

A simple pulse-shape discriminator has been designed to separate signals 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 distribution of the energy deposited. Test results show that even for photons having an energy of 17 keV, the location of most of the interactions can be found unambiguously. The system has also been tested on the most commonly used NaI(Tl)/CsI(Tl) phoswich detector without particular optimisation of the shaping time-constants. These results show that it can work well for gamma-rays below 17 keV. This technique could be very useful in a system which produces more than two decay components, such as a triple phoswich detector, or in a system where pulse-shape discrimination is used for particle identification. (orig.)