Gamma ray spectroscopy with a ⊘19 x19 mm3 LaBr3 : 0.5% Ce3+ scintillator

Pulse height spectra of various sources covering X-ray and gamma ray energies from 10 keV to 6.1 MeV were measured by the first large circle divide19 x 19 mm(3) LaBr3 : 0.5% Ce3+ scintillator. The spectra are compared with that recorded with a same sized NaI:Tl+ scintillator. Excellent energy resolution pulse height spectra are obtained showing that the scaling up from a small (approximate to3 x 3 x 10 mm(3)) sized LaBr3 : Ce3+ scintillator studied initially up to an approximate to 6 cm(3) scintillator does not lead to much deterioration of resolution and light output. Special attention is devoted to the nonproportionality in the response of LaBr3 : Ce3+ and related energy resolution. At high energy LaBr3 : Ce3+ is far superior above NaI:Tl+ in terms of energy resolution and scintillation speed. At energies below 100 keV, NaI : Tl+ shows a better energy resolution.