Advantages and limitations of LSO scintillator in nuclear physics experiments

Light yield, light pulse shape due to /spl gamma/-rays and /spl alpha/-particles, energy and time resolutions for three different samples of the LSO scintillator were studied using an XP2020Q photomultiplier and an S3590-03 photodiode. Light yields of 4200/spl plusmn/200 phe/MeV and 18500/spl plusmn/900 e-h pair/MeV were measured for the PM tube and the photodiode, respectively. The light pulse shape exhibits a pure exponential decay with a time constant of 47.2/spl plusmn/1.3 ns for both /spl gamma/-rays and /spl alpha/-particles. Energy resolutions of 10% and 14.6% for the 662 keV /spl gamma/-rays from a /sup 137/Cs source were obtained for the photomultiplier and the photodiode readout, respectively. A time resolution of 180 ns was observed for /sup 60/Co /spl gamma/-rays at 1 MeV threshold and 400 ps for 100 keV threshold. The study confirmed a number of advantages of the LSO scintillator for nuclear physics experiments, however, for small size samples. For larger volumes the natural radioactivity of the LSO, about 300 counts/s/cm/sup 3/, may limit possible applications. The high number of e-h pairs produced in the photodiodes makes LSO very attractive for small compact scintillation probes.