A study on light collection of small scintillating crystals

Mesurements are described concerning the light collection efficiency of YAP:Ce and CsI(Tl) crystals pillars with thicknesses ranging between 3 and 28 mm and cross-sections of 0.6×0.6 and 1×1 mm2. These measurements have shown that the light collection is strongly dependent on the length of the pillar rather than on its cross-sectional area. A Monte Carlo code has been developed in order to evaluate the light collection efficiency as a function of the pillar geometry and surface treatment. Particular attention has been paid to the light transition through the crystal–photocathode window interface. The possibility to improve light detection by using a new photon detector provided with a YAP photocathode window has been verified.