Applications of the non-negative least-squares deconvolution method to analyze energy-dispersive x-ray fluorescence spectra.

We used the Monte Carlo simulation method to establish a detector response matrix and the non-negative least-squares method to deconvolute x-ray spectra. The simulation and experimental data verified the effectiveness of this method, and the influence of full-width at the half of the maximum calibration accuracy on the deconvolution results was investigated. The non-negative least-squares method had high accuracy and efficiency compared with others.

A New Temperature Correction Method for NaI(Tl) Detectors Based on Pulse Deconvolution.

To overcome the temperature effect of NaI(Tl) detectors for energy spectrometry without additional hardware, a new correction method was put forward based on pulse deconvolution, trapezoidal shaping and amplitude correction, named DTSAC. To verify this method, actual pulses from a NaI(Tl)-PMT detector were measured at various temperatures from -20 °C to 50 °C. Pulse processing and spectrum synthesis showed that the position drift of the Cs 662 keV peak was less than 3 keV, and the corresponding resolution at 662 keV of the sum spectra ranged from 6.

Neutron spectrometry of DO-moderated Cf with Bonner sphere spectrometer.

For neutron spectrometry of the DO-moderated Cf source with a Bonner sphere spectrometer (BSS), it is difficult to use the large and heavy shadow cone to correct the neutron scattering effect. To overcome this problem, Monte Carlo (MC) simulation method was applied to calculate the neutron scattering ratio and to establish the BSS response functions. The simulated response functions were verified by experimental measurements in reference mono-energetic neutron fields.

Gamma spectrum stabilization method based on nonlinear least squares optimization.

To suppress spectral drift in lengthy gamma spectrum measurements, a convenient and practical spectrum stabilization method with software-only adjustment is studied. The gamma energy spectra are recorded in consecutive small time intervals. The drifts in different time intervals relative to the first reference spectrum are estimated with a full spectrum nonlinear optimization technique, and the drifted spectra are corrected and accumulated to form a drift-free spectrum.

PIN silicon diode fast neutron detector.

Two batches of diodes, with different structural ratios (the ratio of area and thickness), were made using different manufacturing processes. The energy response of the first batch to 15 kinds of monoenergetic neutrons ranging from 180 keV to 17.56 MeV was tested, and the neutron source response of both batches to 239Pu-Be neutron source was measured.