Investigation of 3/2$_2^-$ state of $^{9}$Li nucleus with microscopic structure and reaction models

TL;DR

This study combines microscopic structure and reaction models to analyze the low-lying states of the $^{9}$Li nucleus, revealing its cluster structure, deformation, and reaction cross sections at intermediate energies.

Contribution

It introduces a unified microscopic framework to describe $^{9}$Li's structure and reactions, highlighting the 3/2$_2^-$ state's cluster features and deformation.

Findings

Identification of the 3/2$_{2}^{-}$ state with characteristic inelastic scattering distribution.

Evidence of $ ext{alpha} + t$ cluster structure and valence neutron configurations.

Indications of triaxial deformation and di-neutron mixing in $^{9}$Li.

Abstract

The low-lying states of the $^{9}$Li nucleus are investigated with a unified framework of microscopic structure and reaction models. In the structure model, the wave function is fully antisymmetrized and the $^{9}$Li nucleus is described as an $\alpha$ + $t$ + $n$ + $n$ four-body system, and low-lying 1/2$^{-}$, 3/2$^{-}$, 5/2$^{-}$, and 7/2$^{-}$ states are obtained by the stochastic multi-configuration mixing method. Using these wave functions, the quasi-elastic cross section at $E/A$ = 60 MeV and the elastic and inelastic cross sections at $E/A$ = 50 MeV on the $^{12}$C target are calculated in the framework of the microscopic coupled channel (MCC) method. The characteristic inelastic angular distribution is seen in the 3/2$_{2}^{-}$ state, whose $\alpha+t$ cluster structure and valence neutron configurations are discussed in detail. We find the possibility of triaxial deformation and mixing of di-neutron components in the $^{9}$Li nucleus.