Smooth band termination in ¹⁰⁸Sn

Three rotational bands in ¹⁰⁸Sn have been investigated to high frequency via the ⁵⁴Fe(⁵⁸Ni,4p) reaction at 243 MeV. One of these bands is observed to undergo a band crossing at high spin. All three bands show a large decrease in their dynamic moments of inertia, to approximately one third of the rigid body value, as the rotational frequency approaches 1 MeV/ħ. The structures of these bands are thought to be based on 2p-2h proton excitations across the Z=50 shell gap and their properties can be interpreted in terms of cranked Nilsson-Strutinsky calculations. Such calculations predict smooth band terminations for all three struc- tures and a gradual shape change from collective prolate, at low spin, to noncollective oblate at high spin. © 1996 The American Physical Society.