NEW FEATURES OF COLLECTIVE NUCLEAR ROTATION AT VERY HIGH-FREQUENCY INSB-109

Three rotational bands have been discovered in the nucleus Sb-109 that extend in angular momentum to similar or equal to 81/2 (h) over bar. The rotational frequency at the highest spins reaches (h) over bar ome ga similar or equal to 1.4 MeV, the highest frequency so far observed in a heavy nucleus. With increasing frequency the collective moments o f inertia of all three bands smoothly diminish to unexpectedly low val ues, J((2)) similar to 13 (h) over bar(2) MeV(-1), approximately one-t hird the rigid-body value, and, contrary to expectations, the moments of inertia become nearly equal to one another and to those of rotation al bands in the core nucleus Sn-108.