Modern γ-ray spectroscopy and exotic behavior in rare-earth N∼90 nuclei at the limits of excitation energy and angular momentum

Significant advances in our ability to detect γ-ray signals from excited nuclei have been made in recent decades. These advances have allowed a wide range of exciting new phenomena to be discovered throughout the chart of nuclides. A new generation of detectors systems utilizing the γ-ray energy tracking technique will allow this revolution in high-resolution γ-ray spectroscopy to continue. To illustrate the progress made over recent decades the rare-earth nucleus 158Er has been selected as an example. This nucleus exhibits a number of textbook structural changes as it evolves with increasing excitation energy and angular momentum. For example, after undergoing Coriolis induced alignments of high-j neutron and proton pairs, a dramatic prolate collective to oblate non-collective transition takes place via the mechanism of band termination. At the highest spins, a spectacular return to collective rotation is observed in the form of triaxial strongly deformed bands consistent with long standing predictions t...