ABSTRACT
A prompt gamma neutron activation analysis (PGNAA) facility utilizing 252Cf source has been developed for in situ analysis of copper samples. Monte Carlo simulation is employed to determine optimal sizes for neutron moderator, gamma-ray shielding material, and thermal neutron absorber. Subsequently, based on the parameters optimized by MCNP, the PGNAA facility was constructed. Five sets of experimental samples containing low-grade copper concentration of 0 %, 0.5 %, 1 %, 1.5 % and 2 % are measured with the PGNAA facility. The results show that the minimum detectable concentration of copper is 0.218 %. The maximum relative deviation of copper is 8.53 %.
ABSTRACT
A prompt gamma ray neutron activation analysis detection system was developed to detect the heavy metals in sediments by using an (241)Am-Be neutron source and BGO detector. The samples containing cadmium and mercury were used to test the performance of setup. The linear relationship between prompt gamma ray counts and the concentrations was studied. The results showed the counts of the prompt gamma rays from cadmium do not increase linearly with its concentrations, while the prompt gamma ray counts from Hg vary nearly linearly with the concentrations, due to the neutron self-shielding. Then a method was used to correct the effect and the non-linearly response was restored after the correction. And the minimum detectable concentration of Cd and Hg were 52.8 (at 8.484MeV) and 81.6 (at 5.967MeV) ppm, respectively.
