Speaker
Description
6He is one of the simplest nuclei with a halo in the ground state 0+; its study has received significant theoretical attention [1]. In [2], an assumption was made about a halo-like structure in the isobar-analog state of the 3.563-MeV, 0+ 6Li state. This structure is a spatially extended halo-like structure with an alpha particle core and a proton and neutron surrounding it. One of the last theoretical results is the calculations within the ab initio NCSM (no-core shell model) [3]. Calculations showed that the radius of the ground state of 6Li, within the error limits, coincides with the radius of the 3.56 MeV state of 6Li.
Our group is studying the 6Li nucleus, especially its second excited 3.563-MeV, 0+ state for a long time. One of the first results was the Modified diffraction model (MDM) application [4] to existing literature data. The literature differential cross sections for inelastic scattering of 3He + 6Li with excitation of the 2.19 MeV state, 3+ at energies of 34 and 72 MeV and 3.56 MeV, and 0+ state at energies of 24.6 and 27 MeV were analyzed. It was shown that the radius of the 2.19 MeV, 3+ state, within errors, coincides with the radius of the ground state, and the radius of the 3.56 MeV, 0+ state is 2.5 ± 0.2 fm [4] and, within errors, coincides with the radius of 6He, which allows for the possibility of the presence of a halo (proton-neutron, and in some works called tango-halo) [5]. The obtained value is less than the previously predicted radius of this state of 2.73 fm [2].
During last year’s we are adopting “Distorted Wave Born Approximation” (DWBA) to make some qualitative estimations on radii of 6Li excited states. Two new experiments were done: 1) 7Li (d, t)6Li 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; 2) 10B(7Li,6Li)11B experiment was performed on the 7Li beam of the U-400 accelerator beam of the FLNR JINR, Dubna at energy of 58 MeV. The angular distributions for the ground and first excited states of 6Li were obtained. The experimental data were analyzed within the framework of the DWBA. We obtained radial dependences of the form factors and the ANC values for 6Lig.s and 6Li (3.56 MeV) states. The obtained values of the ANC for the 6Lig.s. and 6Li(3.56 MeV) states are similar to those in the literature. This fact confirms correctness of our DWBA analysis. Comparison of the radial dependences of form factors shows that the wave function of the 6Li nucleus in the 6Li (3.56 MeV) state has increased spatial dimension compared to the 6Lig.s. state.
[1] Y. Suzuki, Nucl. Phys. A 528, 395 (1991).
[2] K. Arai et al., Phys. Rev. C 51, 2488 (1995).
[3] D. M. Rodkin, Yu. M. Tchuvil’sky, JETP Letters, 118 (3), 153 (2023).
[4] A.S. Demyanova et al., “Possible existence of neutron-proton halo in 6Li” KnE Energy & Physics, 1, DOI 10.18502/ken.v3i1.1715 (2018).
[5] I.N. Izosimov, Phys. At. Nucl. 80, 867 (2017).
