High spin state in ${}_{}{}^{69}{}_{}{}^{}\mathrm{As}$ and ${}_{}{}^{72}{}_{}{}^{}\mathrm{Se}$ have been excited in oxygen induced reactions on ${}_{}{}^{56}{}_{}{}^{}\mathrm{Mn}$, ${}_{}{}^{54,56}{}_{}{}^{}\mathrm{Fe}$, and ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ targets. On the basis of $\gamma \gamma$ coincidences, angular distributions, and excitation functions, a level scheme of ${}_{}{}^{69}{}_{}{}^{}\mathrm{As}$ is proposed. The following mean lives (in the parentheses) have been determined by the recoil distance Doppler shift method: in ${}_{}{}^{72}{}_{}{}^{}\mathrm{Se}$ with level energies in keV, 862 (5.2 ± 0.5 ps); 1634 (2.7 ± 0.3 ps); 2466 (2.2 ± 0.3 ps); 3770 (9 ± 3 ps); in ${}_{}{}^{69}{}_{}{}^{}\mathrm{As}$, 1307 (1.95 ± 0.05 ns); 2161 (5.1 ± 0.8 ps); 5198 (11.3 ± 1.5 ps). It is suggested that the positive parity states in ${}_{}{}^{69}{}_{}{}^{}\mathrm{As}$ form a rotational aligned $g_{\frac{9}{2}}$ proton band with $\gamma \simeq 30°$. The presumed ${25/2}^{+}$ intruder state features the same deformation as deduced from the ${13/2}^{+}$ → ${9/2}^{+}$ $B\left(E2\mathrm{}\right)\mathrm{}$ value.

NUCLEAR REACTIONS ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}({}_{}{}^{18}{}_{}{}^{}\mathrm{O},p2n){}_{}{}^{69}{}_{}{}^{}\mathrm{As}$, ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}({}_{}{}^{16}{}_{}{}^{}\mathrm{O},p2n){}_{}{}^{69}{}_{}{}^{}\mathrm{As}$, ${}_{}{}^{55}{}_{}{}^{}\mathrm{Mn}({}_{}{}^{16}{}_{}{}^{}\mathrm{O},2n){}_{}{}^{69}{}_{}{}^{}\mathrm{As}$, ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}({}_{}{}^{16}{}_{}{}^{}\mathrm{O},\alpha p){}_{}{}^{69}{}_{}{}^{}\mathrm{As}$, ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}({}_{}{}^{16}{}_{}{}^{}\mathrm{O},2p){}_{}{}^{72}{}_{}{}^{}\mathrm{Se}$; measured $E_{\gamma }$, relative excitation function, angular distributions, recoil distance Doppler shift; deduced $E_x$, $I^{\pi }$, $T_{\frac{1}{2}}$, mixing ratio.

• Received 21 November 1977

DOI:https://doi.org/10.1103/PhysRevC.17.2113