Investigation of the excitation spectrum of [superscript8]He via deuteron inelastic scattering

Abstract

<p>Halo nuclei form due to weak binding at extreme proton-neutron asymmetries near driplines and these uncovered alterations in nuclear shell structure. These halos can exhibit a phenomenon known as a soft dipole resonance. It was postulated that 2⁺ state of ⁸He may be a mixed with lowlying soft dipole resonance state but it is an unsettled issue. In this work, the deuteron inelastic scattering off a neutron halo nucleus, ⁸He, has been studied in inverse kinematics at the IRIS facility at TRIUMF. This study presents findings of first excited state at E = 3.57 &plusmn; 0.02 MeV with resonance width of 0.64 &plusmn; 0.06 MeV along with the ground state. The possibility of absence of low-energy soft dipole resonance in the extracted excitation spectrum might be due to the stronger binding of ⁸He. There is also no intruder s-orbital known in ⁸He which can allow L=1 particle-hole excitation.</p>