Heavy metals detection in sediments using PGNAA method

• A new method for simulating sediment environment was used.
• An original device for detecting heavy metal was designed.
• Non-linearly response caused by the neutron self-shielding effect was restored.
• A smaller minimum detection concentration of Cd and Hg was studied.

A prompt gamma ray neutron activation analysis detection system was developed to detect the heavy metals in sediments by using an 241Am-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 8.484 MeV) and 81.6 (at 5.967 MeV) ppm, respectively.