Temperature dependence of BGO-CsI(Tl) phoswich detector properties

We have studied the variations of the performances, and particularly the discrimination efficiency, of a BGO-CsI(Tl) phoswich detector in the temperature range 2.5-400C. The scintillation decay time evaluation has been carried out by means of a double constant fraction discriminator and a time to amplitude converter on 1 μs shaped pulses. Good discrimination between BGO and CsI(Tl) events has been obtained over the whole temperature range, even though small efficiency variations are present because of the relative displacement of the acceptance window of the discriminator due to the decay time dependence on temperature. A criterium to minimize this effect, useful in particular for the BGO-CsI(Tl) phoswhich, has been developed. (orig.)