10He low-lying states structure uncovered by correlations

TL;DR

This study uncovers the low-lying states of 10He using correlation measurements, revealing an unusual level ordering that suggests shell structure breakdown similar to 12Be.

Contribution

The paper provides the first detailed analysis of 10He low-energy states through angular correlations, revealing anomalous level ordering and shell structure breakdown.

Findings

Identified the 0+ ground state at about 2.1 MeV above threshold.

Observed interference patterns indicating excited states at 4-6 MeV and above 6 MeV.

Revealed shell structure breakdown in 10He similar to 12Be.

Abstract

The 0+ ground state of the 10He nucleus produced in the 3H(8He,p)10He reaction was found at about $2.1\pm0.2$ MeV (\Gamma ~ 2 MeV) above the three-body 8He+n+n breakup threshold. Angular correlations observed for 10He decay products show prominent interference patterns allowing to draw conclusions about the structure of low-energy excited states. We interpret the observed correlations as a coherent superposition of the broad 1- state having a maximum at energy 4-6 MeV and the 2+ state above 6 MeV, setting both on top of the 0+ state "tail". This anomalous level ordering indicates that the breakdown of the N=8 shell known in 12Be thus extends also to the 10He system.