Speaker
Description
The characteristics of various nuclear processes are rather simple to calculate in statistical model [1,2]. In particular, the transition-width distribution is described by the Porter–Thomas equation, there are no correlations between different partial widths, the strength function of $\beta$-transitions $S_\beta (E)$ depends smoothly on energy, and the ratios of the amplitudes for decay via various spin channels follow the Cauchy distribution.
Deviations from the statistical theory have been observed in (p,p’γ ) and (p,γ ) reactions, $\beta^-$ and $\beta^+/EC$-decays [1-4]. Non-statistical effects are closely related to the symmetry of the nuclear interaction and intermediate resonance structure [3,4].
In this report non-statistical effects manifested in reactions involving low-energy protons and in β- decay are analyzed. In (p,γ) reactions for non-analog resonances in N>Z nuclei non-statistical effects are connected with neutron excess and domination of the simple configuration such as proton-particle neutron-hole in the wave function of nonanalog resonances [1-3]. The association of non-statistical effects in (p,γ) reactions and in the $\beta$-decays with spin–isospin $SU(4)$ symmetry are discussed. The non-statistical effects taking into account non-statistical correlations in $E2$ and $M1$ γ-transitions for the γ-decay of the non-analog resonances in (p,γ) reactions are analysed.
[1] I.N. Izosimov, Physics of Particles and Nuclei, 30,131(1999).
[2] I.N. Izosimov, JINR Preprint E6-2024-14. Dubna, 2024; http:www1.jinr.ru/Preprints/2024/14(E6-2024-14).pdf.
[3] I.N. Izosimov, et al, Phys. Part. Nucl., 42,1804(2011). DOI:10.1134/S1063779611060049
[4] O.E. Kraft, Yu.V.Naumov, V.M.Sigalov, I.V. Sizov, Sov. J. Part. Nucl., 17, 573 (1986).
