He++pElastic Scattering below 1 MeV

The cross section at 90° (lab) for elastic scattering of protons by ${\mathrm{He}}^3$ has been measured from $E_p=0.125\mathrm{}$ MeV to above 1 MeV. No significant departure of the $s$-wave phase shifts from the hard-sphere value is seen. Experimental upper limits for the dimensionless reduced width of a $J=0^{+}$ state vary from 4×${10}^{-3\mathrm{}}$ at the lowest energy to ${10}^{-4\mathrm{}}$ at 1 MeV, and lead to the assignment of $T=0\mathrm{}$ to the $0^{+}$ state at 20 MeV in ${\mathrm{He}}^4$.