Spin-orbit coupling in the scattering of protons by helium is expected to result in polarization of the scattered proton beam. This effect has been established by performing a double scattering experiment, in the form of a polarizer-analyzer arrangement, and measuring the amount of polarization. These data, used in conjunction with the phase shift analysis of the single scattering differential cross-section data, give conclusive evidence that the $P_{\frac{1}{2}}$ and $P_{\frac{3}{2}}$ energy levels in the compound nucleus of ${\mathrm{Li}}^{5*}$ are inverted.

• Received 17 September 1951

DOI:https://doi.org/10.1103/PhysRev.85.80