# Enhanced E1 transition between weakly-bound excited states in the nucleus 27Ne

## TL;DR

This paper models the enhanced E1 transition in 27Ne, explaining it through deformation and weakly-bound neutron effects, particularly the halo structure and shell-structure peculiarities.

## Contribution

It provides a theoretical explanation for the strong E1 transition in 27Ne by incorporating deformation and halo neutron effects, advancing understanding of weakly-bound nuclear states.

## Key findings

- E1 transition strength explained by prolately deformed states
- Transition between halo components accounts for observed strength
- Shell-structure influences weakly-bound neutron behavior

## Abstract

Inspired by the recently-reported strong electric-dipole (E1) transition between the weakly-bound first and second excited states, 3/2- at 765 keV and 1/2+ at 885 keV, in the nucleus 27Ne, the E1 transition is estimated in a model by properly taking into account the effect of both deformation and weakly-bound neutrons. In addition to both the spin-parities, 1/2+ and 3/2-, and observed nearly degenerate energies of the two excited states, the observed order of magnitude of the E1 transition strength between the two states is very naturally explained in the case that these two excited states are prolately deformed, in terms of the transitions between the halo components of the wave functions of the weakly-bound odd-neutrons, s1/2 -> p3/2 and s1/2 -> p1/2, in addition to the large probability of the p3/2 component in the weakly-bound neutron [330 1/2] orbit. The large probability is the result of the shell-structure unique in weakly-bound or resonant neutrons.