Upper Limit ofTNonconservation in the ReactionsMg24+α⇄Al27+p

Time-reversal invariance has been tested via detailed balance in the compound-nuclear reactions ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}+\alpha \rightleftarrows {}_{}{}^{27}{}_{}{}^{}\mathrm{Al}+p$. The relative differential cross sections agree within the experimental uncertainties, leading to an estimated upper limit for the ratio of the $T$-nonconserving to the $T$-conserving reaction amplitudes of (2-4)×${10}^{-3\mathrm{}}$. The same upper limit is found for the nuclear matrix elements which are odd with respect to time reversal.