The level structure above 13-MeV excitation energy in ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ was investigated through the reaction ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}(\alpha ,\alpha ){}_{}{}^{10}{}_{}{}^{}\mathrm{B}$ in the energy range from $E_{\alpha }=2.0\mathrm{} \mathrm{to} 4.3$ MeV. Excitation functions for elastically scattered $\alpha$ particles were measured in 20-keV steps at six c.m. angles of 67.8, 89.7, 113.5, 141.8, 154.9, and 169.1°. Besides the two strong resonances observed at $E_{\alpha }\simeq 2.21 \mathrm{and} 4.26$ MeV, respectively, two additional resonances were required to fit the excitation functions. An $R$-matrix calculation was used to obtain spin and parity assignments of $3^{+}$, $1^{+}$, $3^{+}$, and $2^{-}$ to the levels at excitation energies of $E_x=13.19,13.72,14.25,\mathrm{and} 14.66$ MeV, respectively. The partial widths of $\alpha$-particle decay and total widths of these states were also determined. In addition, the excitation function from $E_{\alpha }=1.4\mathrm{} \mathrm{to} 2.0$ MeV was measured at ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}={89.7}^{\circ }$, and no obvious resonances were observed in this energy region. Possible correlations of the strong $\alpha$-particle levels to the $\alpha$-particle core-excited threshold-state model are also discussed.

• Received 5 January 1973

DOI:https://doi.org/10.1103/PhysRevC.8.972