Energy resolution measurements of LaBr_3:Ce scintillating crystals with an ultra-high quantum efficiency photomultiplier tube

摘要

The performance of the new prototype of high quantum efficiency PMT (43 at 380 nm), Hamamatsu R7600U-200, was studied coupled to a LaBr_3:Ce crystal with the size of φ12.5mm × 12.5mm. The energy resolution results were compared with ones from two PMTs, Hamamatsu R7600U and R6231MOD, with 22 and 30 quantum efficiency (QE), respectively.Moreover, the photodetectors were equipped with tapered and un-tapered voltage dividers to study the non-linearity effects on pulse height distribution, due to very high peak currents induced in the PMT by the fast and intense light pulse of LaBr_3:Ce. The results show an energy resolution improvement with UBA PMT of about 20, in the energy range of 80–662 keV, with respect to the BA one.