The Treatment of Efficiency of NaI(Tl) Detector By Using Monte Carlo Simulation

An efficient Monte Carlo computer program for simulation and calculation of the total and full energy peak efficiency (absolute and intrinsic) of the cylindrical NaI(Tl)detector (with different: volumes, source-detector separation and gamma rays energies) is described. All the fundamental physical processes (photoelectric effect, compton scattering effect and pair production effect) occurring inside the detector are taken into account. Very fast analytical expressions for the absorption coefficients are obtained. The same program can be used to calculate the response function of the detector to gamma ray. The results show quite well agreement with experimental data and with other calculations within error rate less than 2%. The results can be used in gamma spectroscopy and determining the activity of sources.