Isoscalar Pairing and Pairs in Nuclei

Abstract : The question whether isoscalar pairing between neutrons and protons gives rise to correlation effects similar to those observed for the isovector pairing between identical nucleons remains unanswered. Some schematic properties of “ideal” isoscalar-pair condensates are pointed out. Isoscalar-pairing correlations can be probed with deuteron transfer reactions, which are the subject of an experimental programme at GANIL. It is shown that simple predictions based on the assumption of a pair vibrational behaviour can assist in the interpretation of such experiments. A different but related question is whether the low-energy structure of N~Z nuclei can be interpreted in terms of spin-aligned isoscalar pairs. This hypothesis can be tested, for example by measuring magnetic and quadrupole moments of isomeric levels in odd-odd N=Z nuclei, such as for instance 94Ag or 90Rh, which is one of the aims of the S3 project in preparation at GANIL.