Optimization of in situ prompt gamma-ray analysis of lake water using a HPGe-252Cf probe

A self-designed HPGe-252Cf probe based on neutron-induced prompt gamma-ray techniques is described in this work to identify the optimum conditions of various-intensity 252Cf neutron sources employed in the in situ measurement of elemental concentrations in water. 252Cf neutron sources weighing 1.3, 8.0, 44 and 260 μg, resepctively, were available for the laboratory test which simulated the field operation. The optimized operating depth for each neutron source was determined according to the minimum detectable concentration of chlorine measured by the 6111 keV prompt gamma ray, resulting in optimum neutron-source depths below the water line of 20, 35, 70 and 105 cm, respectively. The detecting efficiencies and detection limits for other elements were evaluated and calculated at optimized conditions to judge potential application of the probe in a rapid field survey. (orig.)