Alpha-Particle Angular Distributions with Respect to Spin Direction

Angular distribution of alpha particles with respect to the spin direction of residual nuclei from fusion of 176-MeV ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ with ${}_{}{}^{150}{}_{}{}^{}\mathrm{Nd}$ has been measured with the spin spectrometer. Below the Coulomb barrier, the ratio of the 90° to 0° yields with respect to spin direction increases with decreasing $E_{\alpha }$. This effect is not shown by a statistical-model calculation using penetrabilities for spherical potentials, which suggests that the $\alpha$-mitting nuclei are deformed with their longest axis perpendicular to the spin direction. If so, the deformation increases as the spin rises from ∼ 34 to $64\hslash$.