Energy Levels and Electromagnetic Transitions inN15from theC13(He3,pγ)N15Reaction

Abstract

Excited states of ${\mathrm{N}}^{15}$ have been studied by the ${\mathrm{C}}^{13}({\mathrm{He}}^3,p\gamma ){\mathrm{N}}^{15}$ reaction. Proton spectra were measured with a magnetic spectrometer at two angles for ${\mathrm{He}}^3$ energies of 2 and 5 MeV. Excitation energies of 9.054±0.004, 9.225±0.003, 9.829±0.004, and 10.072±0.004 MeV were obtained for levels in ${\mathrm{N}}^{15}$. Electromagnetic branching ratios were measured for levels at 8.31, 8.57, 9.05, 9.16, 9.22, 9.76, 9.83, 9.93, 10.07, and 10.45 MeV. A comparison was made with theoretical branching ratios calculated from shell-model wave functions for levels at 8.31, 8.57, 9.05, and 9.93 MeV. Measured branching ratios for the first three of these levels agree with calculated ratios for shell-model levels of $J^{\pi }={\frac{1}{2}}^{+},{\frac{3}{2}}^{+},\mathrm{and} {\frac{1}{2}}^{+}$, respectively. Proton-$\gamma$-ray angular-correlation measurements for levels at 9.05, 9.16, and 9.22 MeV indicate $J=\frac{3}{2}$ for the 9.16-MeV state, $J=\frac{1}{2} or \frac{3}{2}$ for the 9.05-MeV level, and $J=\frac{3}{2}$ (90% probability) or $J=\frac{1}{2}$ (10% probability) for the 9.22-MeV level.