Neutron correlations and clustering in neutron-rich nuclear systems

TL;DR

This paper reviews recent experimental progress on neutron correlations and clustering in neutron-rich nuclei, highlighting findings from quasi-free scattering experiments on various isotopes and revealing insights into neutron halos, dineutron correlations, and cluster structures.

Contribution

It presents new experimental data and analysis on neutron correlations, halo structures, and clustering phenomena in neutron-rich nuclei, extending quasi-free scattering techniques to unstable isotopes.

Findings

Weak neutron halo in $^{17}$B with small s-wave component

Universal surface localization of dineutron correlations in Borromean nuclei

Evidence for $ ext{4}n$ resonance and cluster structures in $^{10}$Be

Abstract

In this paper, we will briefly review the recent progress on neutron correlations and clustering in neutron-rich nuclei from quasi-free scattering experiments. The quasi-free ($p$, $pn$) reaction was measured for Borromean nuclei $^{11}$Li, $^{14}$Be, and $^{17}$B. A surprisingly small $s$-wave component was found for $^{17}$B, revealing a weak neutron halo in $^{17}$B, and the comparative study of the three nuclei shows the surface localization of dineutron correlation and its universality in Borromean nuclei. The two-neutron emission of $^{16}$Be was also studied, finding strong dineutron correlation in $^{16}$Be(g.s.) but weak correlation in $^{16}$Be($2^+$). Two missing-mass measurements using $^{4}$He($^{8}$He, $^{8}$Be) and $^{8}$He($p$, $p\alpha$) reactions provided evidence for the $^{4}n$ resonance, but the $^{3}n$ resonance was not supported by the recent experiment employing the $t(t,^3$He)$^3n$ charge-exchange reaction. The quasi-free $(p,p \alpha)$ reaction has been extended to unstable nuclei, and the recent experiment unravels the $\alpha$-$2n$-$\alpha$ molecule-like cluster structure of $^{10}$Be(g.s.).