Calculation of total and full energy peak efficiencies of Ge(Li) and NaI(Tl) detectors by introducing the mean chord length

Abstract An approximate method has been given to determine the total, the full energy peak, the intrinsic, the intrinsic full energy peak efficiencies and the full energy peak-to-total ratio of Ge(Li) and NaI(Tl) detectors, for the gamma rays coming from a point source which is placed on the detector axis at a distance D from the detector surface.