Detection efficiency evaluation for low energy of a NaI(Tl) scintillation detector

To improve the characterization of the detection efficiency of a NaI(Tl) scintillation detector in the low energy range, measurements and Monte Carlo simulations were performed with a certified reference material (CRM) and disk sources. The detection efficiency as modeled. In the MCNP simulation, the detection efficiency dropped as expected at 33.17 keV. The X-ray escape correction factors of a 204Tl disk source and MCNP simulations were compared, a factor of the 204Tl was similar. Moreover, Correcting the X-ray escape and using fewer sources than the CRM resulted in better detection efficiency for the NaI(Tl) detector in the low energy range.