A full spectral analysis method for the gamma spectrum: weighted library least squares.

The traditional library least squares approach (LLS) is affected by the inconsistency of the statistical uncertainties of different channels in a gamma spectrum, which leads to large fluctuations in the analysis results. This work proposes a weighted library least squares approach (WLLS) that uses the square root of the count to weight the regression objective function and has implemented a verification experiment based on Prompt Gamma Neutron Activation Analysis (PGNAA). The results showed that, after weighing using the square root of the count, the fluctuation level of statistical uncertainty in the spectrum was reduced from 44.34 to 2.25. After the analysis of the WLLS approach, the average standard deviation of the results was reduced to at least 0.37 times that of the LLS approach.

Development of a compensation system for thermal neutron measurements based on Cd(Cu)-covered NaI(Tl) detectors.

A compensation system based on NaI (Tl) detectors and cadmium sheet was proposed for thermal neutron detection in the neutron/gamma field. The system consisted of two identical NaI (Tl) detectors covered with copper and cadmium sheets, respectively. The Cd-covered NaI (Tl) recorded the prompt gamma rays produced by the 113Cd (n, γ)114Cd reaction, while the Cu-covered structure "rejected" the background gamma rays. The moderated thermal neutron fluxes at different distances from an Am-Be neutron source, calibrated by the activation foil method, were investigated using the compensation system. The thermal neutron detection efficiency of this compensation system was compared to those obtained by the CdZnTe detector and He-3 proportional counter. The feasibility of the compensation system used as a thermal neutron counter was demonstrated by the obtained results.