One-Neutron Removal Cross Sections for $^{16}$N Isomeric State

Abstract

It is well known that the enhancement of halo neutron removal cross sections in neutron halo nuclei. This is one of the evidence for the neutron halo structure. Because the valence neutron of the isomeric state in $^{16}$N is considered to be mainly occupying in the s-orbital, we studied the nuclear structure of $^{16}$N as a candidate for neutron halo nucleus. In this study, we measured one-neutron removal cross sections $\sigma _{-1n}$ using secondary beams of $^{16}$N with a mixture of ground and isomeric states. We used two types of primary beams, $^{15}$N and $^{18}$O, to produce $^{16}$N beams with different isomeric ratios (8.7, 24.2a $^{16}$N beam with a large isomeric ratio is large compared to that obtained with another beam with a small isomeric state. This result suggests that the $^{16}$N isomeric state is considered to have a neutron-halo-like structure.