A prototype phoswich detector for small angle correlation measurement

The performance of a prototype fast/slow scintillator telescope consisting of a 75μ fast plastic (BC 412) as ΔE and a 4 mm thick slow plastic (BC444) as E detector is reported. The size of the detector is 10mm x10mm. Two different methods have been employed to couple the scintillators. In one case, detectors were coupled using a very thin layer of BC600 optical glue. Alternately it was tried to sandwich them thermally keeping them under controlled temperature for two hours. The temperature was set at 70deg C. The phoswich detector so formed was coupled to Thorn-EMI 9826B PMT with optical cement. The applied bias voltage was -1000V and anode signal was taken for processing. In case of optical gluing, dead layer due to excess glue material affects the light output whereas in thermal gluing, the trapped air layer degrades it