J.F. Sharpey-Schafer

Quadrupole Moment of a High-Spin Yrast Trap in Gd 147

Static quadrupole interactions of three

Quadrupole moments of yrast isomers in 144, 147, 148Gd

^{147}\mathrm{Gd}

Yrast isomers and very high spin states in 148, 149, 151, 152Dy and 147Gd

isomers in single crystals of hexagonal gadolinium have been observed. The quadrupole moments increase with increasing spin and imply a substantial (oblate) deformation (

Quadrupole moment of high-spin yrast trap in /sup 147/Gd

\ensuremath{\beta}\ensuremath{\sim}0.2

Single particle nature of the yrast line at high angular momentum in 152Dy

) for the 500-ns high-spin yrast trap.

Single-particle states at very high spin in the light dysprosium isotopes

Abstract Isomeric nuclei of 144, 147, 148 Gd were produced by 120, 124 Sn ( 28 Si , x n ) fusion evaporation reactions and implanted into single crystals of Gd. The perturbed angular distribution spectra at various orientations of the crystal axis are dominated by static quadrupole interactions. The ratio of quadrupole moment Q to spin I was determined for the 10 + isomer in 144 Gd, the 13 2 + , 27 2 − and (T 1 2 = 510 ns ) isomers in 147 Gd, and the 9 − isomer in 148 Gd. In addition a tentative value of I = ( 47 2 ± 1) was obtained for the spin of the 510 ns isomer in 147 Gd. The observed quadrupole moments provide the first experimental evidence for the substantial oblate deformation ( β ∼ −0.2) predicted by the deformed independent particle model of Neergard, Dossing and Sagawa for high-spin isomers in 147 Gd. The oblate deformation is observed to increase when the number of valence nucleons (and the isomer spin) increases, and furthermore when the neutron core at N = 82 is broken. The g -factors and quadrupole moments of the 3 − and 10 + core states in 146 Gd have also been deduced.

Measurement of the linear polarization of continuum gamma rays from (32S, xn) reactions to prolate and oblate rare-earth nuclei

Abstract We have studied level schemes for the feeding and decay of high-spin isomers in the nuclei 148, 149, 151, 152 Dy and 147 Gd. A variety of techniques involving γ-ray spectroscopy with pulsed heavy-ion beams have been applied including linear polarization, γ-γ correlations and recoil distance measurements. The general aspect of these level schemes is in accordance with the idea that the states near and along the yrast line can be described by a spheroidal shell model in which the nucleus is axially symmetric with respect to the total spin. In these cases the spin is generated not by collective rotation, but by alignment of many single-particle orbits around a common axis.

The ground-state rotational band in 159Tb

Static quadrupole interactions of three

Remeasurement of lifetimes for high spin states in 154Er

^{147}\mathrm{Gd}

Lifetimes for Levels above the "Rotational Phase Change" inEr158

isomers in single crystals of hexagonal gadolinium have been observed. The quadrupole moments increase with increasing spin and imply a substantial (oblate) deformation (