Speaker
Description
$^{6}$He is one of the simplest nuclei with a halo in the ground state 0$^{+}$; its study has received considerable theoretical attention [1]. In [2], an assumption was made about a halo-like structure in the isobar-analogue state of the 3.56 MeV state, 0$^{+}$ $^{6}$Li. This structure is a spatially extended halo-like structure with an alpha particle core and a proton and neutron surrounding it. In [3], it was shown that the radius of the 3.56 MeV, 0+ state is 2.5 $\pm$ 0.2 fm and, within errors, coincides with the radius of $^{6}$He, which allows for the possibility of the presence of a halo (proton-neutron, and in some works called tango-halo) [4]. Let us recall that the spatial structure of the $^{6}$He nucleus was predicted to be quite complex, in which correlations of two types appeared: “cigar” and “dineutron”.
The question arises: does the structure of the state change so much when going from $^{6}$He to the isobar analogue in $^{6}$Li that it requires the introduction of a special type of “tango-halo” [4]. To answer this question, new experimental data were required. Not long ago, the $^{7}$Li(d,t)$^{6}$Li experiment was performed on the deuteron beam of the U-150M cyclotron at the Institute of Nuclear Physics (Almaty, Republic of Kazakhstan) at an energy of 14.5 MeV. The angular distributions of the studied nuclear reactions cover the angle range from 18$^\circ$ to 128$^\circ$ (lab.). The angular distributions for the ground and first four states were obtained: 2.19, 3.56, 4.31 and 5.36 MeV. The experimental data were analysed within the framework of the DWBA method and the coupled channel method. The analysis is currently ongoing to estimate the radii of low-lying excited states. There is some indication of an increased radius of the 3.56 MeV state, confirming its halo nature.
[1] Y. Suzuki, Nucl. Phys. A 528, 395 (1991).
[2] K. Arai et al., Phys. Rev. C 51, 2488 (1995).
[3] A.S. Demyanova et al., KnE Energy & Physics, 1, DOI 10.18502/ken.v3i1.1715 (2018).
[4] I.N. Izosimov, Phys. At. Nucl. 80, 867 (2017).
| Section | Nuclear structure: theory and experiment |
|---|
