Asymétrie du temps: Polarisation et pouvoir d'analyse dans les réactions nucléaires

Measurements of the proton polarization in the reactions ⁷Li(³He, $\text{p}$)⁹Be and ⁹Be(³He, $\text{p}$)¹¹B and of the analyzing powers of the inverse reactions, initiated by polarized protons at the same c.m. energies, show significant differences which imply the failure of the polarization-analyzing-power theorem and, prima facie, of time-reversal invariance in these reactions. The reaction ²H(³He, $\text{p}$)⁴He and its inverse have also been investigated and show some smaller differences. A discussion of the instrumental asymmetries is presented.