Enhanced Discrimination in Co-doped LaBr3Ce

Abstract

LaBr $_3$ :Ce crystal scintillator can be co-doped with various alkaline earth metals to improve light output and energy resolution of the basic scintillator. Another benefit is improvement of alpha/gamma discrimination via pulse shape analysis. LaBr $_3$ :Ce contains a low level of actinium contamination, which produces an alpha particle background in radiation energy spectra. This background is difficult to discriminate from gamma rays. Conversely, the addition of co-dopant into the crystal makes the alpha response much easier to distinguish. LaBr $_3$ :Ce, Sr, for example, produces a slow decay component in the scintillation pulse when excited by radiation. The amplitude of the slow decay component changes in response to a gamma ray versus a heavy charged particle. The change in pulse shape can be used to eliminate the alpha background or enable detection of neutron reaction products.