Analytical expression to calculate total and full-energy peak efficiencies for cylindrical phoswich and lanthanum bromide scintillation detectors

An analytical expression for the total and full-energy peak efficiencies for cylindrical phoswich and lanthanum bromide (LaBr3:Ce) scintillation detectors is derived. This approach depends on the accurate analytical calculation of two important factors; the path length d, the photon traverses within the active volume of a gamma detector, and the geometrical solid angle Ω, subtended by the source to the detector at the point of entrance. In addition, the attenuation of photons by the detector housing materials is also treated by calculating the photon path length through these materials. The comparisons with the experimental and Monte Carlo method data reported in the literature indicate that the present method is useful in the efficiency calibration of the cylindrical phoswich and lanthanum bromide scintillation detectors.