Neutron halo effect on direct neutron capture and photodisintegration

Abstract

A novel effect of the neutron halo formation is presented for the direct radiative neutron capture where a p-wave neutron is captured into an s orbit with neutron halo by emitting an E1 \ensuremath{\gamma} ray. As an example, an enormous enhancement is demonstrated for the cross section of $^{12}\mathrm{C}$(n,\ensuremath{\gamma}${)}^{13}$C(1/${2}^{+}$) at low energy in excellent agreement with a recent experiment. The S factor of the final state is evaluated. The inverse process, i.e., photo disintegration is discussed for an example of $^{11}\mathrm{Be}$. A sharp but nonresonant peak near the threshold is obtained as a result of the neutron halo in its anomalous ground state.