Quasiparticle spectra near the yrast line

The configuration assignments for the known energy levels of the odd-$A$ deformed nuclei in the mass range $150lAl190$ have been systematically reviewed. For each nucleus, a summary is given of the intrinsic states that are considered well identified, and the main arguments that support particular assignments are outlined. A discussion is presented of the theoretical framework used in the analysis which is basically the Nilsson single-particle model with pairing correlations and Coriolis coupling taken into account, and with appropriate consideration given to vibrational excitations and their mixing with the one-quasiparticle states. Energy systematics are shown for the one-quasiparticle excitations and for the gamma-vibrational excitations (most of which have significant one-quasiparticle admixtures), and these systematics are discussed in terms of current theory.

A Survey of Nonrotational States of Deformed Odd-A Nuclei (150<A<190)

A description of high-spin phenomena in atomic nuclei is presented from both the experimental and theoretical points of view. The characteristic features of collective nuclear motion, such as rotational bands, band crossings, and backbending, as well as noncollective aspects, like high-spin isomers and irregular decay patterns, are discussed in detail. Recent achievements of the cranking model including the independent quasiparticle and the shell correction methods are reviewed. Changes in the structure of nuclei excited up to the highest possible angular momenta are analyzed; in particular, angular momentum alignment effects, shape changes, possible phase transitions, and sudden rearrangements in the single-particle structure are discussed. Phenomena related to the nuclear quasicontinuum spectra are also examined.

High-spin phenomena in atomic-nuclei

Evidence for a “singularity” in the nuclear rotational band structure

A review of the empirical data on intrinsic states of odd-$A$ nuclei in the mass range $151\ensuremath{\le}A\ensuremath{\le}193$ and $A\ensuremath{\ge}221$ is presented. Global summaries of the data are presented in tables for each isotopic and isotonic chain, wherein the excitation energy, the $log\mathrm{ft}$ values, the moment-of-inertia parameter, and the decoupling parameter (for $K=\frac{1}{2}$ bands) are listed for single-particle, vibrational admixed, and pure vibrational states. Similar data are separately presented for three-quasiparticle excitations in the rare-earth region. Taking guidance from the systematics on nuclear deformation, the single-particle deformed potential for axially symmetric and reflection-symmetric shapes (the Nilsson model) modified by the hexadecapole deformation is used to interpret the data. Other variations of the Nilsson model, which include axially asymmetric shapes ($\ensuremath{\gamma}$ deformation) and especially reflection-asymmetric shapes (octupole deformation), have also been used to interpret the data in certain limited regions. Systematics for the intrinsic excitations are presented and discussed in terms of these models. The newly emerging regions of the octupole-quadrupole deformation and superdeformation are also discussed.

H. Ryde

Papers

Strongly perturbed positive-parity bands in odd-mass erbium isotopes

Angular velocity expansions of nuclear rotational energies

Location and description of some low-lying high-spin states in 155Gd

High-spin rotational and three-quasiparticle excitations in 177Ta

Rotational states and coriolis interaction in 171Yb