Spin-isospin excitations in ${}^{13}\mathrm{N}$ have been studied by means of the $\left({}^3\mathrm{He},t\right)$ and $\left({}^3\mathrm{He},tp\right)$ reactions at a bombarding energy of $E\left({}^3\mathrm{He}\right)=450\mathrm{MeV}$. The zero-degree $\left({}^3\mathrm{He},t\right)$ spectrum is found to be similar to those from the $(p,n)$ reactions at intermediate energies, suggesting a simple direct reaction mechanism at $E\left({}^3\mathrm{He}\right)=450\mathrm{MeV}$. The Gamow-Teller $\left(\mathrm{GT}\right)$ states with $J^{\pi }=1∕2^{-}$ and $3∕2^{-}$ have been strongly excited at ${\theta }_{\mathrm{lab}}=0°$. The angular distribution of cross sections for the ${}^{13}\mathrm{C}\left({}^3\mathrm{He},t\right){}^{13}\mathrm{N}$ reaction and the elastic ${}^3\mathrm{He}$ scattering off ${}^{13}\mathrm{C}$ were obtained at ${\theta }_{\mathrm{lab}}=0°–17°$ and at ${\theta }_{\mathrm{lab}}=2°–22°$, respectively. The obtained experimental results were compared with calculations performed in distorted-wave Born approximation. Microscopic structures of the states in ${}^{13}\mathrm{N}$ have further been studied by observing decay protons in coincidence with high-energy tritons measured at ${\theta }_{\mathrm{lab}}=0°$. The branching ratios for proton decay from the $\mathrm{GT}$ states in ${}^{13}\mathrm{N}$ to the final low-lying $T=0$ states in ${}^{12}\mathrm{C}$ were obtained. The wave functions of the excited states in ${}^{13}\mathrm{N}$ are discussed on the basis of obtained experimental data and relevant theoretical calculations.

• Received 12 February 2004

DOI:https://doi.org/10.1103/PhysRevC.69.064327