E.M. Beck

High-spin state spectroscopy in 165, 166Yb

Abstract Level schemes of 165Yb and 166Yb are studied up to high spins. Triple γ-ray coincidence spectra are analyzed for the first time. The observed bands in both nuclei are interpreted in terms of the cranked-shell model. In particular, the continuation of the lowest i 13 2 single quasineutron aligned band beyond the first observed backbend is seen in an odd-N nucleus and the interaction strength between this band and the three-quasiparticle band is evaluated. Constancy of the moment of inertia in 166Yb is observed at high spins and interpreted.

Superdeformed bands in Nd nuclei

Abstract Superdeformed bands were found in 134, 136 Nd. Their dynamic moments of inertia are about as large as those of the known superdeformed bands in 135 Nd and 132 Ce, corresponding to β ≈ 0.5. A high probability for staying in band is measured for the discrete superdeformed bands in 134, 136 Nd, in contrast to the unresolved superdeformed ridges.

New structures at high spin in 159Er

Abstract The nucleus 159 Er was studied with the HERA γ-ray spectrometer. Three rotational bands were extended to higher spins, and three new bands were found. It is shown that specific orbitals rather strongly influence the high-spin behavior, some states remaining collective (somewhat triaxial), others evolving towards a non-collective oblate structure. One of the new bands is a higher- K band, similar to those found in heavier nuclei.

Particle-hole states at high spin in 150Dy

Abstract The level scheme of the nucleus 150 Dy up to spin around 40 was obtained using the reaction 114 Cd( 40 Ar, 4n). Above spins 20 to 22 — the highest obtainable from the valence nucleons — the breaking of the 146 Gd pproton and neutron cores occurs in separate parallel cascades.