Spins and Lifetimes of the 6.91- and 6.95-MeV Excited States ofCa40

Resonant scattering of $\gamma$ rays by the 6.91- and 6.95-MeV excited states of ${\mathrm{Ca}}^{40}$ has been observed with a 30-${\mathrm{cm}}^3$ Ge(Li) detector. The reaction ${\mathrm{F}}^{19}(p,\alpha ){\mathrm{O}}^{16}$ served as the source of the resonant $\gamma$ rays. The angular distributions of the 6.91- and 6.95-MeV radiations were found to be compatible only with the assignment of spin 2 to the 6.91-MeV level, and of spin 1 to the 6.95-MeV level. No evidence for cascade de-excitation of the two levels was found. If $\frac{{\Gamma }_0}{\Gamma }$ is assumed to be unity for both levels, the observed scattering cross sections correspond to ground-state transition widths ${\Gamma }_0\mathrm{}\left(6.91\right)=0.18\mathrm{}\pm 0.03$ eV and ${\Gamma }_0\mathrm{}\left(6.95\right)=0.47\mathrm{}\pm 0.06$ eV.