Dissertation summary

SUMMARY

Sergey A. Tolstov

Mathematical and methodical support of the estimation of low activities of radionuclides for scintillation gamma- and beta-spectrometry

Keywords: scintillation spectrometry, radionuclides activities estimation, maximum likelihood method.

The problem of creation of the algorithms, based on the maximum likelihood method, for estimation of low activity of radionuclides from gamma- and beta-spectra is solved.

The radionuclides activities estimators based of the maximum likelihood method have been developed. The estimators raise the activity measurement accuracy for the scintillation gamma- and beta-spectrometry.
The necessity of taking into account of the following factors: statistical noise in calibration spectra, the influence of the pulse-height analyzer spectrometric scale parameters deviation and the variations of the investigated sample mass density, has been grounded for the problem of estimation of the radionuclides activities from gamma- and beta spectra by the maximum likelihood method. The ways of taking into account of those factors have been developed.
The statistical criterion for detecting of the "insignificant" parameters of the spectrum model has been developed. The algorithm, adapting spectrum model by means of exclusion of the "insignificant" parameters has been developed on the basis of the criterion. Here "insignificant" parameter denote parameter, whose exclusion from the spectrum model does not make worse the accuracy of the estimation of the other parameters.

The procedures of the activity measurements have been created on the basis of the developed algorithms. The procedures have been tested, coordinated and registered as MVI 656.MN -98 and MVI.MN 655 in Centre of Measurement Standards, Standardization and Metrology of Republic of Belarus. The developed algorithms are used in the production-run scintillation spectrometers and radiometer of "Atomtex" enterprise (Minsk).

The results of the research can be used when developing Software for scintillation beta-, gamma and beta-gamma- spectrometers and radiometers.

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