Elastic Scattering ofHe3byHe4from 17.8 to 30.0 MeV

Differential cross sections for the elastic scattering of ${\mathrm{He}}^3$ by ${\mathrm{He}}^4$ have been measured from 21.9 to 155.0° (c.m.) at ${\mathrm{He}}^3$ energies of 17.79, 19.99, 22.00, 23.98, 26.00, 28.00, and 30.00 MeV (lab). The relative standard deviations of the data are typically less than 2.5%, but become larger at angles where the cross section is very low. In addition to relative errors, the over-all error includes a standard deviation of 3% in the cross-section scale. The measurements are compared with theoretical calculations using the resonating-group method in the one-channel approximation. Differences between theory and experiment can be qualitatively understood as being caused mainly by the omission of reaction channels in the theory.