Phase Shifts in Proton-Alpha-Scattering

Phase-shifts in $S$ and $P$ waves are found that fit the observed scattering of protons by helium (4) within the experimental accuracy of the recent Minnesota results. The $S$ wave phase is negative and rather small. The $P_{\frac{1}{2}}$ and $P_{\frac{3}{2}}$ waves have different phase-shifts, both positive, but there are two sets of possible values, one corresponding to a normal doublet in ${\mathrm{Li}}^5$, the other to an inverted doublet. In both cases there is resonant scattering and strong polarization of the proton beam. Measurement of the polarization would decide between the doublets. The values of the phase-shifts presented are those that minimize the sum of squares of percent differences between observed and calculated differential cross sections.