p-He3Scattering at 9.75-Mev Proton Energy

The differential cross section for the elastic scattering of 9.75-Mev protons from ${\mathrm{He}}^3$ has been measured in the range of center-of-mass angles from 30 to 150 degrees. The cross section varies from 345 millibarns/steradian at 30 degrees, through a minimum of 18.2 mb at 110 degrees, and rises to 84.5 mb at 150 degrees. Comparison of the data with the distributions calculated theoretically by Swan gives only rough agreement, the closest being for ordinary forces in the four-body system. This conflicts with the good agreement obtained by Swan with the 14-Mev $n$-T data of Coon et al., in which a symmetric exchange force scheme was clearly preferable.