DETEFF: An improved Monte Carlo computer program for evaluating the efficiency in coaxial gamma-ray detectors

We present the new improved version of our Monte Carlo program DETEFF for detector efficiency calibration in gamma-ray spectrometry. It can be applied to a wide range of sample geometries commonly used for measurements with coaxial gamma-ray detectors: point, rectangular, disk, cylindrical, and Marinelli sources (the last being newly included in this version). The program is a dedicated code, designed specifically for computation of gamma-ray detector efficiency. Therefore, it is more user-friendly and less time consuming than most multi-purpose programs that are intended for a wide range of applications. The comparison of efficiency values obtained with DETEFF and MCNP4C for a typical HpGe detector and for energies between 40 and 1800 keV for point, cylindrical, and Marinelli geometries gave acceptable results, with relative deviations <2% for most energies. The validity of the program was also tested by comparing the DETEFF-calculated efficiency values with those obtained experimentally using a coaxial HpGe detector for different sources (point, disk, and 250 mL Marinelli beaker) which contain 241Am, 109Cd, 57Co, 139Ce, 85Sr, 137Cs, 88Y, and 60Co. The calculated values were in good agreement with the experimental efficiencies for the three geometries considered, with the relative deviations generally being below 3.0%. These results and those obtained during the application of the previous versions indicate the program's suitability as a tool for the efficiency calibration of coaxial gamma-ray detectors, especially in routine measurements such as environmental monitoring.