Dependence on the gamma radiation energy of the NaI(Tl) scintillation detector efficiency

A mathematical method, based on Monte Carlo procedure, has been elaborated in order to determine the dependence of the NaI(Tl) scintillation detector efficiency on the gamma radiation energy. The calculus program elaborated for an isotropic point source takes into account the other parameters the detector efficiency depends on: the NaI(Tl) scintillation crystal dimensions and the source-detector distance. The result obtained by Monte Carlo Method, for two NaI(Tl) crystals of different dimensions are compared with the results given in the literature and with those ones obtained experimentally. A good agreement of the results can be observed.(authors)