A novel and universal polarization phenomenon

Abstract:  We present a simple, yet previously unnoticed, polarization phenomenon involving ion beams accelerated at medium energies. In the 7Li(12C,12C)7Li(7/2-) reaction at 24 MeV/A, a large longitudinal polarization of the excited 7Li outgoing product has been observed, by measuring the angular correlations between the fragments (alpha+t) of the decay of the populated 7/2- resonance. A theoretical account of the reaction process supports the idea that we are dealing with a universal effect present under very general conditions whenever there is a transfer of angular momentum from the relative motion of the colliding nuclei to the internal degrees of freedom of the projectile. We make an attempt at unveiling the origin of this effect with a simple kinematical argument.