Speaker
Prof.
Pieter Van Isacker
(GANIL, France)
Description
It is shown that the aligned neutron-proton pair with angular momentum
J=9 and isospin T=0 plays a central role in the low-energy spectroscopy of
the N~Z nuclei approaching 100Sn. This observation is made in the context
of the spherical shell model on the basis of a realistic two-nucleon
interaction constructed for the g9/2 orbit. Shell-model results are analyzed
in terms of a variety of two-nucleon pairs corresponding to different
choices of their coupled angular momentum J and isospin T. The analysis is
performed exactly for four holes (96Cd) and carried further for six and
eight holes (94Ag and 92Pd) by means of a mapping to an appropriate
version of the interacting boson model.
On the basis of these results one concludes that a realistic model can be
formulated in terms of s (with J=0) and b (i.e., aligned J=9) bosons. Due to
its simplicity, such a model could be of use to elucidate the main structural
features of N~Z nuclei in this mass region. Examples of simple predictions
of such a model will be given.
