Full-energy peak efficiency determination for the 4π gamma-ray detector by a numerical simulation method

Abstract EN

The 4π gamma-counting system is a well suited for the analysis of small amounts of environmental samples of low activity, as it can combine both low background and high detection efficiency due to the 4π solid angle.

In the present work, a new numerical simulation method (NSM) is proposed to calculate the full-energy peak, the total efficiencies and to correct the coincidence summing effect for the HPGe well-type detector geometry.

This method is based on the calculation of the solid angle subtended by the well-type detector at a non-axial point extended to cylindrical sources measured inside detector cavity.

The attenuation of the photon within the source material itself (self-attenuation), the source container and the detector’s end-cap and dead layer materials is also included in this method.

Low activity aqueous solution γ-ray sources contain (60Co and 88Y) in small vials are usually used in the Belgium Nuclear Research Center (SCK.CEN), Boeretang 200, B-2400 Mol, Belgium, to calibrate the γ-ray p-type HPGe well-type detectors in the energy range from 60 up to 1836 keV in the laboratory of gamma-spectroscopy.

The measured efficiency values are in good agreement with those obtained by the numerical simulation method.