Observation of Charge-Asymmetry Effects in the ReactionH2(α, H3)He3AT 27.4 MeV c.m.

The differential cross section for the reaction ${}_{}{}^2{}_{}{}^{}\mathrm{H}(\alpha , {}_{}{}^3{}_{}{}^{}\mathrm{H}){}_{}{}^3{}_{}{}^{}\mathrm{He}$ was measured from 31° to 149° c.m. with an 82-MeV $\alpha$-beam. The measurements were made to test the Barshay-Temmer theorem which requires ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ yields to be independently symmetric about 90° c.m. We find a pronounced and angle-dependent deviation from 90° symmetry, as large as 10% at some angles. Our results thus constitute the first clear-cut evidence for a violation of the above theorem.