Study On Quantitative Technique For The Sample With High Cross Section In Neutron Radiography

Neutron photographic technology has become a popular quantitative analysis technology.Quantitative analysis of H-containing substances in the sample is a major application of neutron photographic.However,due to H and other elements have a high scattering cross-section,which will make a large number of scattering neutrons reach the detector,making the neutron image blur distortion,to the subsequent quantitative analysis difficult.Therefore,an effective quantitative analysis technology for high scattering cross section samples is needed.Neutron energy spectrum hardening and scattering neutrons are two problems in quantitative analysis of high scattering cross section samples.In this paper,the effective neutron cross section is used instead of the neutron macro section to correct the error caused by the spectrum hardening.The relationship between the effective neutron cross section and the sample thickness was calculated by Monte Carlo program MCNP5.The effective section calibration curve method was proposed to correct the quantitative analysis error caused by energy spectrum hardening.The neutron radiography correction method based on the point scattering function is adopted to correct the image ambiguity and the quantitative analysis error caused by the scattered neutrons.Firstly,the theoretical expression of point scattering function is deduced in theory,and simplified under certain conditions.On this basis,the concept of equivalent scattering intensity and equivalent distance is put forward.The research on the properties of the point scattering function is studied.The Monte Carlo method is used to study the properties of the point scattering function.The equivalent scattering intensity and the equivalent distance parameterization are given.The equivalent scattering intensity and the equivalent distance are studied.Method,the method of obtaining the point scattering function for the distance between the detector sample and the sample thickness is given.An iterative algorithm for quantitative analysis of samples with high scattering cross section is proposed by combining the above two methods.The results of this study show that the effective cross-sectional scale curve method can effectively correct the analysis error caused by the hardening effect of the energy spectrum.The simplified point scattering function model proposed in this paper can be used to calculate the obtained point scattering function by Monte Carlo method.The results show that the algorithm can well correct the quantitative analysis error caused by the scattering effect and the energy spectrum effect.The results show that the proposed method can be used to quantitatively analyze the six different geometric shapes of the Monte Carlo method.