Study of linearity and internal background for LaBr3(Ce) gamma-ray scintillation detector

Cerium-doped lanthanum bromide, LaBr3(Ce), crystal is the latest among the family of scintillation counters and shows same attracting properties for gamma spectroscopy that makes it a suitable solution for security, medical, geophysics and high energy physics applications. Among these properties are good density (5.1 g/cm3), brightness (>65000 photon/MeV), time resolution and excellent energy resolution (<3% FWHM at E_gamma=662 keV, the best obtainable with scintillators). LaBr3(Ce) exhibits a proportional light yield response to gamma-ray energy. Very good linearity was seen up to 2 MeV. LaBr3(Ce) has also relatively high intrinsic radiation background due to naturally occurring 138La and 227Ac radioisotopes. A good use of LaBr3(Ce) needs an accurate determination of the self activity, particularly when low background is required or when events are collected at very low trigger rates. The impact of internal background on energy resolution and linearity is discussed.