Application Of Neutron Activation Analysis In Geological Exploration

With the comprehensive development of the economy and society,the demand for mineral resources is increasing.It is important to improve exploration efficiency in minerals resource exploration.Neutron activation analysis technology has a high level of element identification ability and high-quality automatic analysis level.Because of its strong recognition,high ac-curacy,and non-destructive testing advantages,it is regarded as a nuclear analysis technology and can be applied to minerals resource exploration.This study was carried out by using the combination of Geant4（GEometry ANd Tracking）simulations and experimental measurements.The first step is to use Geant4 software program-ming to verify the feasibility of the neutron activation analysis for geological exploration.The second step is to use the neutron activation analysis method to analyze the elemental composi-tion and content of the ore.The specific method is to obtain theγenergy spectrum of samples after irradiation experiments,then design energy spectrum processing program based on Mat-lab in order to obtain the composition of the real ore.The analysis of the content of the ore is realized by the relative measurement method.This study provides ideas for applying neutron activation analysis to the exploration of geological ores.The main research contents include:（1）A neutron activation analysis model for geological ores was established by using Geant4 software,and the production yield of corresponding radionuclide⁵⁶Mn after neutron activation of samples with different Mn contents was counted.The simulation results show that the yield of⁵⁶Mn has a good linear relationship with the mass of Mn in the sample,and the mass of Mn in the sample can be calculated from the amount of⁵⁶Mn produced.（2）Relevant neutron irradiation experiments were carried out on the neutron beam device of China Spallation Neutron Source Back-n White Neutron Source（CSNS Back-n White Neu-tron Source）,and the simulated geological ore samples with known elemental composition and content prepared in advance Simultaneously irradiated with real geological ore samples of unknown element composition and content,theγenergy spectrum produced by the neu-tron irradiation of the above samples was measured using the CSNS low-background gamma spectrometer system.（3）Based on theγenergy spectrum obtained from the experiment,the characteristic peaks are found by using Origin’s fast peak finding function,the characteristic peak area of the target nuclide is calculated by curve fitting method,and the theoretical yield of the target nuclide is calculated by using the theoretical formula.Finally,the reason for the error between the two is analyzed.（4）A γenergy spectrum processing program is designed based on Matlab.The program includes a variety of spectral smoothing methods,peak finding methods,and peak area cal-culation methods.After comprehensively comparing the processing results of different meth-ods,the polynomial least squares method was selected as the spectral smoothing method and derivative method of theγenergy spectrum obtained in this experiment.As the peak finding method of the energy spectrum,the linear background method is used as the peak area cal-culation method of the energy spectrum.The program can realize the search for weak peaks,and the calculation results are reliable.However,since some target nuclide characteristic peak counts are too small,they are greatly affected by statistical fluctuations,so the target nuclide characteristic peaks with too few counts will not be used for activation analysis calculations.The following results were obtained through research:It is feasible to apply neutron acti-vation analysis to geological exploration.The analyzed ore sample is manganese ore,and the Mn content in the ore accounts for approximately 4.45%of the total mass.It is the important factor affecting the analysis efficiency in neutron activation analysis.According to the above research content and experimental results,it is proved that the neutron activation analysis method can be used in the composition and content analysis of unknown ores in geological exploration.The conclusions obtained in this paper can be used as a reference for similar research in the future.