SUPERFLUIDITY IN ASYMMETRIC NUCLEAR-MATTER

The onset of superfluidity in isospin-asymmetric nuclear matter is inv estigated within the BCS theory. A neutron-proton superfluid state in the channel S-3(1)-D-3(1) comes about from the interplay between therm al excitations and separation delta mu of the two Fermi surfaces. The superfluid state disappears above the threshold value of the density-a symmetry parameter alpha=(n(n)-n(p))/n similar or equal to 0.35. For l arge enough shift between the two Fermi surfaces delta mu=1/2(mu(n)-mu (p)) the transition to the normal state becomes a first-order transiti on and a second gap solution develops. This solution, however, corresp onds to a metastable superfluid state which is unstable with respect t o the transition to the normal state.