Hou, XL (reprint author), Acad Sinica, Inst High Energy Phys, POB 2732, Beijing 100080, Peoples R China.
Repeated irradiation enhances the precision and sensitivity of INAA based on short-live radionuclides, but entail systematic losses due to dead time. The relative standard deviation in the net peak area decreases with the square root of the number of cycles while the systematic bias increases with it. The limits of decision, detection and determination decrease in a somewhat more complicated way with the number of cycles. The derived formulation is applied to the determination of selenium in hair by the 161.9 keV photopeak of Se-77m, T-1/2=17.8 s.