Rotational bands near the [ital Z]=50 closed shell: [sub 51][sup 111]Sb

Rotational states have been identified in [sup 1][sub 51][sup 11]Sb for the first time. Three decoupled ([Delta][ital I]=2) bands extending to over 1 MeV in rotational frequency have been observed. At the highest frequencies, the [ital scrJ][sup (2)] moments of inertia for these three bands are seen to decrease steadily to unexpectedly low values; this is interpreted as evidence for a novel form of band termination. One of these bands is interpreted as being based on the [pi][ital h][sub 11/2] orbital coupled to a deformed [([pi][ital g][sub 9/2])[sup [minus]2][direct product]([pi][ital g][sub 7/2])][sub 0+] state of the [sup 1][sub 50][sup 10]Sn core. The interaction strength for the alignment of a pair of [ital h][sub 11/2] neutrons has been extracted and compared with calculations. Two possible quasiparticle configurations are discussed for the other decoupled bands. Two strongly coupled ([Delta][ital I]=1) bands have been identified and both shown to involve the [([pi][ital g][sub 9/2])[sup [minus]1][direct product]([pi][ital g][sub 7/2])[sup 2]] configuration. A large number of spherical states have also been observed, which can be explained on the basis of valence protons coupled to spherical states in the [sup 110]Sn core.