A self-absorption correction method for self-emitting γ-rays under complex medium conditions

Abstract

The invention relates to a self-absorption correction method of a self launching gamma ray under a complex medium condition. The method includes the following steps that detection efficiency and each energy parameter of gamma rays of different energies are measured; the measured counting rate of each energy parameter is converted to activity degree, and the activity degree serves as an initial activity degree value; a set of ratio Smi (Tm, Ei) under the test condition is obtained through comparing the initial activity degree obtained from each feature gamma ray with the initial activity degree corresponding the gamma ray of the largest branching ratio; a self-absorption factor of each feature gamma ray is obtained by the adoption of the above ratio; radioactive isotope activity degree fim corresponding to each feature gamma ray is obtained according to the self-absorption factor of each feature gamma ray; the fim is converted to quality of the radioactive isotope. According to the self launching gamma ray self-absorption correction method under the complex medium condition, self launching gamma ray self-absorption correction is conducted to an object to be tested when medium density, ingredients and thickness are variable parameters and the transmission measurement correction cannot be implemented by the adoption of an additional transmission source due to limitation of environmental conditions.

Description

technical field [0001] The invention relates to a correction method, in particular to a self-absorption correction method for self-emitting gamma rays under complex medium conditions. Background technique [0002] Most radioactive material isotopes can emit more than one γ-ray, and these γ-rays will interact with substances, so the medium in which the radioactive material is located will absorb part of the γ-ray, that is, the self-absorption effect of the medium. The main factors affecting the self-absorption of γ-rays are the density, composition and thickness of the medium, etc. The type of reaction between the ray and the substance is related to the energy of the ray and the type of medium, so γ-rays with different energies will self-absorb independently of each other in the medium effect, which varies with media density, composition, and thickness. Under certain conditions, the three parameters are known, and the self-absorption factor can be calculated by existing algo...

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Problems solved by technology

[0003] The radioactive material in the material can be qualitatively and quantitatively analyzed by measuring the γ-ray emitted by the material itself, and the isotope ratio of the nuclear material is also called the enrichment degree and the quality of the isotope of interest. However, there is generally a problem of self-absorption correction of the γ-ray , and nuclear materials exist in different forms in different substances, and the density, thickness and composition of the medium are not completely the same, so the methods of self-absorption correction are also different

[0004] Usually, the nuclear material for enrichment analysis has a single medium composition, the sample can meet the requirements of gamma-ray measurement of infinite thickness, and the density and activity distribution are uniform; while the nuclear material for mass quantitative analysis has complex medium composition, density and radioactivity. Inhomogeneous or approximately uniform activity distribution

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