Feasibility study on rare earth ion exchange resin saturation analysis based on PGNAA technique.

In this work, prompt gamma ray neutron activation analysis technique was used to monitor the REEs saturation in resin. A facility consisted of a D-T neutron generator, a BGO detector and a 3He detector was established and applied to analyze REEs (Gd and Sm) samples. Neutron self-shielding effect was also corrected. The enriched Gd and Sm in resin were close to saturation at about 400 min. The results showed a satisfactory agreement with the XRF tests, which demonstrated that PGNAA was sufficient for monitoring REEs saturation in resin.

Design of a DT neutron source based PGNAA facility for element determination in aqueous solution.

A DT neutron source-based prompt gamma ray neutron activation (PGNAA) facility for bulk sample analysis was designed and developed in this research. The aqueous samples containing chlorine and boron with known concentration were determined for the calibration curve by the facility. The neutron self-shielding effect was corrected by internal standard method. The minimum detectable concentration of boron and chlorine are 1.37 ± 0.42 and 12.51 ± 3.80 mg/L, respectively. Finally, five mixture aqueous solution samples were measured for the facility performance test. The maximum relative deviation of boron and chlorine are 4.49% and 5.32% respectively.

Research on the NIQAS device for hazardous goods identification based on PGNAA technology.

In the research, the Nuclide Identification and Quantitative Analysis System (NIQAS) for the identification of hazardous goods was designed and optimized by MCNP simulations. With the D-T neutron generator and HPGe detector set as the core of device, the modules, including reflector, moderator and shielding, etc., were optimized by a Signal-to-Noise Ratio (SNR) evaluation method. Moreover, the NIQAS device was set up for measuring the hazardous goods, and the type identification was discussed based on the established logical decision. Finally, a Graphical User Interface (GUI) was designed and the minimum detection time was further investigated.

MCNP benchmark of a 252Cf source-based PGNAA system for bulk sample analysis.

A MCNP model of a252Cf source-based prompt gamma-ray neutron activation analysis (PGNAA) system for bulk sample analysis was benchmarked. The indium foils activation and aqueous samples containing chlorine were measured using the PGNAA system, and the experimental data compared to the simulations. The discrepancies between the measurements and simulations are within 6% and 20% for thermal neutron flux and prompt gamma-ray response, respectively. The results show that the simulations agree well with the measurements, and demonstrate the proposed MCNP model can represent the system.

Efficiency calibration of HPGe detector in a PGNAA system for the measurement of aqueous samples.

In this work, a method was proposed for efficiency calibration of HPGe detector employed in a prompt gamma-ray neutron activation analysis (PGNAA) system for large aqueous sample analysis. Experimental measurements of a reference surface gamma-ray source were combined with efficiency transfer method to obtain efficiency of a volumetric source. Then efficiency curve over the energy range 0.5-8.5 MeV were determined with prompt gamma-rays of chlorine. To evaluate the performance of the calibration curve, an internal standard method was used to determine the aqueous sample containing manganese based on the calibration curve. The 7.058 MeV and 7.243 MeV manganese gamma-ray peaks were used to calculate the mass of manganese. The relative deviations of calculated values and actual value were 5.0% and 6.5%, respectively.

Designing a new type of neutron detector for neutron and gamma-ray discrimination via GEANT4.

Design of a new type of neutron detector, consisting of a fast neutron converter, plastic scintillator, and Cherenkov detector, to discriminate 14-MeV fast neutrons and gamma rays in a pulsed n-γ mixed field and monitor their neutron fluxes is reported in this study. Both neutrons and gamma rays can produce fluorescence in the scintillator when they are incident on the detector. However, only the secondary charged particles of the gamma rays can produce Cherenkov light in the Cherenkov detector. The neutron and gamma-ray fluxes can be calculated by measuring the fluorescence and Cherenkov light. The GEANT4 Monte Carlo simulation toolkit is used to simulate the whole process occurring in the detector, whose optimum parameters are known. Analysis of the simulation results leads to a calculation method of neutron flux. This method is verified by calculating the neutron fluxes using pulsed n-γ mixed fields with different n/γ ratios, and the results show that the relative errors of all calculations are <5%.