Test of Time-Reversal Invariance in the ReactionsMg24+d⇄Mg25+p

No evidence for a violation of time-reversal ($T$) invariance has been found in a study of the inverse reactions ${\mathrm{Mg}}^{24}+d\rightleftarrows {\mathrm{Mg}}^{25}+p$ using approximately 10-MeV deuterons and 15-MeV protons. In order to reduce systematic uncertainties, the reactions were compared by measuring, as a function of incident energy, the ratio of differential cross sections at angles corresponding to maxima in the angular distributions. Particular attention was paid to accurately determining solid angles, peak areas, counter efficiencies, electronic efficiencies, contributions of target impurities, and beam energies. Ratios for the two reactions agree to within an over-all uncertainty (standard deviation) of 0.3%. Lack of an adequate model for the reaction makes quantitative interpretation of the result difficult. However, a tentative upper limit of 0.3% is set on the ratio of the $T$-noninvariant to $T$-invariant reaction amplitudes.