Study of Unbound Levels inN14by theC12(He3, pγ)N14Reaction

The 8.49-, 8.96-, and 9.17-MeV unbound levels of ${\mathrm{N}}^{14}$ have been studied by particle-$\gamma$ angular-correlation measurements for the ${\mathrm{C}}^{12}({\mathrm{He}}^3, p\gamma ){\mathrm{N}}^{14}$ reaction at 8.92 MeV bombarding energy. These levels were found to $\gamma$ decay in competition with proton decay with the width ratios $\frac{{\Gamma }_p}{{\Gamma }_{\gamma }}=3.7\mathrm{}\pm 1.1, 4.09\pm 0.49, \mathrm{and} 10\pm 3$, respectively. The spin and parity of the ${\mathrm{N}}^{14}$ 8.96-MeV level have been definitively established as $J^{\pi }=5^{+}$. The $\gamma$ widths of the $E2\mathrm{}$ transitions from the 8.96- and 8.49-MeV levels have been compared with shell-model predictions. In addition, an unusual result was obtained for the ${\mathrm{N}}^{14}$ 7.03-MeV level. While at $E_{{\mathrm{He}}^3}=5.11\mathrm{}$ MeV, the $m=0\mathrm{}$ substate of this level was predominantly populated, it was found that at $E_{{\mathrm{He}}^3}=8.92\mathrm{}$ MeV the $\mathrm{}\left|m\right|=1\mathrm{}$ substates were strongly populated. The latter has been interpreted as due to $s=1\mathrm{}$ transfer in a possible heavy-particle stripping reaction.