Direct mass measurements of 19B, 22C, 29F, 31Ne, 34Na and other light exotic nuclei

TL;DR

This paper reports precise mass measurements of 16 light neutron-rich nuclei, including first measurements for some, supporting the existence of neutron halos in certain isotopes and providing new data on their nuclear structure.

Contribution

First direct mass measurements of $^{19}$B, $^{22}$C, $^{29}$F, and $^{34}$Na, advancing understanding of exotic light nuclei and halo phenomena.

Findings

$^{22}$C exhibits a two-neutron halo with a $ u2s_{1/2}^2$ configuration.

$^{31}$Ne shows a single-neutron halo with a 2$p_{3/2}$ orbital.

$^{19}$B's halo development is hindered by valence neutron configuration.

Abstract

We report on direct time-of-flight based mass measurements of 16 light neutron-rich nuclei. These include the first determination of the masses of the Borromean drip-line nuclei $^{19}$B, $^{22}$C and $^{29}$F as well as that of $^{34}$Na. In addition, the most precise determinations to date for $^{23}$N and $^{31}$Ne are reported. Coupled with recent interaction cross-section measurements, the present results support the occurrence of a two-neutron halo in $^{22}$C, with a dominant $\nu2s_{1/2}^2$ configuration, and a single-neutron halo in $^{31}$Ne with the valence neutron occupying predominantly the 2$p_{3/2}$ orbital. Despite a very low two-neutron separation energy the development of a halo in $^{19}$B is hindered by the 1$d_{5/2}^2$ character of the valence neutrons.