Cross sections of $1n$-removal reactions from the neutron-rich nucleus ${}^{37}\mathrm{Mg}$ on C and Pb targets and the parallel momentum distributions of the ${}^{37}\mathrm{Mg}$ residues from the C target have been measured at $240\mathrm{MeV}/\text{nucleon}$. A combined analysis of these distinct nuclear- and Coulomb-dominated reaction data shows that the ${}^{37}\mathrm{Mg}$ ground state has a small $1n$ separation energy of ${0.22}_{-0.09}^{+0.12}\mathrm{MeV}$ and an appreciable $p$-wave neutron single-particle strength. These results confirm that ${}^{37}\mathrm{Mg}$ lies near the edge of the “island of inversion” and has a sizable $p$-wave neutron halo component, the heaviest such system identified to date.

• Received 13 March 2014

DOI:https://doi.org/10.1103/PhysRevLett.112.242501