Speaker
Description
The probability of the $\beta$-transition is proportional to the product of the lepton part described by the Fermi function $f( \textit{Q}_{\beta} - E)$ and the nucleon part described by the $\beta$-decay strength function $S_{\beta}(\textit{E})$ . Until recently, experimental investigations of the $S_{\beta}(\textit{E})$ structure were carried out using total absorption gamma-ray spectrometers $(TAGS)$ and total absorption spectroscopy methods, which had low energy resolution. With $TAGS$ spectroscopy, it became possible to demonstrate experimentally the resonance structure of $S_{\beta}(\textit{E})$ for Gamow–Teller ($GT$) $\beta$-transitions [1]. However, $TAGS$ methods have some disadvantages arising from low energy resolution of $TAGS$ spectrometers. Modern experimental instruments allow using nuclear spectroscopy methods with high energy resolution to study the fine structure [2] $S_{\beta}(\textit{E})$.
In this report the fine structure of $S_{\beta}(\textit{E})$ in halo nuclei is analysed. When the parent nuclei has $nn$ Borromean halo structure, than the Gamow-Teller resonance and pygmy resonances in $GT$ $\beta$-decay strength function $S_{\beta}(\textit{E})$ in daughter nuclei may have structure corresponding to $np$ tango [3,4] halo. When neutron excess is high enough, resonances in $S_{\beta}(\textit{E})$ may simultaneously have both $nn$ Borromean halo component and $np$ tango halo component and form so-called mixed halo [3,4]. Analysis of the $S_{\beta}(\textit{E})$ structure in halo nuclei allow to determine the most suitable region for the Wigner $SU(4)$ spin-isospin symmetry. Value $Z/N \approx\ 0.5 - 0.6$ may correspond to the $SU(4)$ spin-isospin symmetry region.
- Yu.V. Naumov, A.A. Bykov, I.N. Izosimov, Sov.J.Part.Nucl., $\textbf{14}$, 175(1983).
https://www.researchgate.net/publication/233832321 - I.N. Izosimov, V.G. Kalinnikov, A.A. Solnyshkin, Phys. Part. Nucl., $\textbf{42}$, 1804(2011). DOI: 10.1134/S1063779611060049
- I. N. Izosimov, Physics of Particles and Nuclei Letters $\textbf{16}$, 754 (2019). DOI: 10.1134/S1547477119060207
- I. N. Izosimov, EPJ Web of Conferences $\textbf{239}$, 02003 (2020).
DOI: 10.1051/epjconf/202023902003
| Section | Nuclear structure: theory and experiment |
|---|
