One-neutron halo structure inC15

Abstract

The one- or two-neutron removal reactions as well as reaction cross sections for ${}^{14,15}\mathrm{C}$ on carbon target have been studied by using $110A\text{MeV}$ ${}^{22}\mathrm{Ne}$ primary beam on Riken Projectile Fragment Separator in RIKEN. The longitudinal momentum distributions of ${}^{13,14}\mathrm{C}$ fragments from ${}^{15}\mathrm{C}$ and ${}^{13}\mathrm{C}$ fragments from ${}^{14}\mathrm{C}$ breakup have been measured at $83A\text{MeV}$ by means of direct time-of-flight method. Full width at half maximum (FWHM) of the distributions have been determined to be $71\pm 9\text{MeV}∕c$ and $223\pm 28\text{MeV}∕c$ for ${}^{14}\mathrm{C}$ and ${}^{13}\mathrm{C}$ from ${}^{15}\mathrm{C}$, and $195\pm 21\text{MeV}∕c$ for ${}^{13}\mathrm{C}$ from ${}^{14}\mathrm{C}$. The FWHM for ${}^{13}\mathrm{C}$ fragments from ${}^{15}\mathrm{C}$ and ${}^{14}\mathrm{C}$ breakup are consistent with the Goldhaber model’s prediction. While the FWHM of ${}^{14}\mathrm{C}$ fragments from ${}^{15}\mathrm{C}$ is much smaller, which confirms the experimental results from MSU and GANIL, an anomalous enhancement from its neighbors has been observed in the measured reaction cross section of ${}^{15}\mathrm{C}$. The experimental data are discussed in the framework of the Glauber model. The analysis of both the fragment momentum distributions and reaction cross sections indicates a dominant $s$-wave component in the ground state of ${}^{15}\mathrm{C}$.