Measurement of talc in flour by the prompt-gamma ray neutron activation analysis method

Prompt gamma-ray neutron activation analysis method (PGNAA) was used to measure the talc content in flour. Neutron activation prompt gamma spectrum measured by NaI(Tl) detector has complex components, poor energy resolution, and high Compton plateau, how to obtain accurate element content from the prompt γ spectrum is one of the core problems of PGNAA. To reduce the systematic uncertainty caused by the variation of the neutron energy spectrum and γ self-absorption in different samples, the spectral decomposition method based on library least-squares was improved. As a result, the average relative deviation between the calculated values from measured spectra and the theoretical values based on the known composition was reduced from 6.1% to 0.3%. The relative uncertainty of 30 measurements on the same sample was reduced from 4.8% to 3.0%. The detection time can be reduced to 1 min, which meets the requirement of on-line measurement for talc in flour.