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Information × Registration Number 0217U000407, 0112U005028 , R & D reports Title Nuclear processes involving atomic shell popup.stage_title Head Fedotkin Sergey, Registration Date 02-02-2017 Organization Scientific Center "Institute for Nuclear Research" of National Academy of Sciences of Ukraine popup.description2 In the statistical model of Thomas-Fermi the estimates are obtained for the averaged total cross sections for the processes of the photoelectric effect and single-photon annihilation of positrons and atomic electrons. In the calculations of the cross sections used the analytical expression for the density of the atomic electrons in Taitz approximation for the average potential. Estimates of cross sections obtained by statistical method and the approximate quantum mechanical calculations for both processes are in good agreement for large charges Z. The proposed statistical method is an approximation, but it is more appropriate to calculate the total cross sections of the this processes because of the high complexity of other approaches. The proposed approach can be used to calculate the probabilities of various processes involving all the electrons of the atomic shell. For the first time identified the experimental values of the effective cross section of the excitation process 9Be nucleus at the annihilation of positrons and atomic electrons via direct detection of neutrons. This cross section equals sigma ef (beta +) = 5.4 *10^-28 cm2. It is shown that the experimental value of the effective cross section for this process is the same order of magnitude with the weighted average of the experimental section 9Be reactions (gamma, n) 8Be for photon energies in the range from 1.78 MeV to 5 MeV. Product Description popup.authors Вишневський Іван Миколайович Желтоножський Віктор Олександрович Коломиєць Володимир Михайлович Кривенко-Еметов Ярослав Дмитрович Саврасов Андрій Миколайович popup.nrat_date 2020-04-02 Close