Monte Carlo model of NaI(Tl) detector unit for investigation of X-ray spectra in the energy range from 3 to 150 keV

Full text: To obtain original spectrum of any X-ray source - for instance X-ray tube - with the help of NaI(Tl) detector unit it is necessary first to find the response of the system to monoenergetic photons in the energy range of interest and appropriate geometry [1]. For this purpose a Monte Carlo program was created which imitates all important interactions of the incident photons in the crystal and surroundings, non-linearity ti the detector response, and the light collection process. Calculated spectra are compared to experimental ones obtained with 2 mm crystal for a set of standard sources: 55Fe, 109Cd, 241Am, and 57Co. It is clear that the distortion of each source line caused by the poor energy solution, process of the radiation scattering, and incomplete light collection can be taken into account to provide coincidence of calculated and experimental results. Thus it seems realistic to reconstruct initial spectrum of an arbitrary X-ray source on the basis of the model created. [1] R.P.Gardner, Avneet Sood. A Monte Carlo simulation approach for generating NaI detector response functions (DRFs) that accounts for nonlinearity and variable flat continua, NIM B213 (2004) 87-99