Application of modern anticoincidence (AC) system in HPGe γ-spectrometry for the detection limit lowering of the radionuclides in air filters

The use of active and passive shields can substantially reduce the Minimum Detectable Activity (MDA) of the γ-ray counting systems, rejecting events induced by cosmic-rays or by environmental radioactivity. However, the size and geometry of the samples lead to limitations in the background reduction in routine measurements. The Minimum Detectable Activity (MDA) values for low energy of γ-ray emitting radionuclides (<200 keV) deposited in three typical air filter geometries have been compared for anticoincidence and single HPGe detector mode of γ-spectrometry systems. The relative increase in the Figure Of Merit (FOM) values from to 10-37% has been achieved for AC counting mode for radionuclides of 210Pb, 234Th, 235U and 226Ra deposited on the three kinds of air filters.