A correlated background in invariant mass spectra of three-body systems

The high-spin structure of the nucleus 183Re has been studied following the 176Yb(11B,4n) reaction. High- K, multi-quasiparticle excitations compete with collective rotation in the formation of the yrast and near-yrast structures. Broken-pair (i13/2)^2 excitations (t-bands) play a dominant role, generating considerable angular momentum both along and perpendicular to the prolate symmetry axis. The stability of axially symmetric, prolate shapes is explored through comparisons with potential-energy-surface calculations. The possible onset of oblate rotation at high angular momentum is discussed.