Gamma ray spectroscopy with a O19×19 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 O19×19 mm³ 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 (≈3×3×10 mm³) sized LaBr₃:Ce³⁺ scintillator studied initially up to an ≈6 cm³ 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.