Configuration-dependent pairing and deformation in 163Er

Recent Nuclear Structure Studies in Rapidly Rotating Nuclei

“…Quasiproton crossing, based (25) on aligned low-Q hl 1 / 2 orbitals below the Fermi level, however, are observed up to hm � 0.5 MeV. The existence of sizeable proton pair correlations, therefore, must remain up to this rotational frequency, where static neutron pair correlations are greatly reduced, see the ensuing dis cussion and (31)(32)(33)(34)(35)(36)(37). This observation not only implies that the quenching of static neutron and proton pair correlations (1 1) is uncoupled, but also emphasizes the role of particle alignment in the reduction of pair correlations.…”

“…These plots are given both in the limit of correlated (upper) and uncorrelated (lower) behavior of these systems with respect to the shape and neutron pair degrees of freedom. Just as the irregular pattern of lx(m) indicates a noncorrelated, or single particle, behavior of 150DY 8 4 (59) with respect to the shape degree of freedom, a similar pattern of N(l) indicates (3 1, 58, 60) an uncorrelated behavior of rapidly rotating odd-N ytterbium isotopes (31,36,(61)(62)(63)(64)(65)(66)(67) with respect to the neutron pair degree of fr eedom. The energy associated with the addition of the least bound pair of neutrons coupled to spin zero and positive parity in odd-mass ytterbium isotopes, i.e.…”

“…Similarly, the discontinuity in the aligned angular momentum plot (upper left-hand portion of Figure 9) is just the backbend associated with the shift of the yrast sequence of 1 6 8Hf9 6 (24) to a different intrinsic confi guration. Particle-number plots for the lowest positive-parity configurations both in odd-and even-N ytterbium isotopes (31,36,55,(61)(62)(63)(64)(65)(66)(67)(68)(69)(70) and for the lowest negative-parity configuration in odd-N ytterbium isotopes 9 are compared at small and large rotational frequencies in Figure 10. The change from the linear behavior of N(J.,) with minimal configuration depen dence at small rotational frequencies to an irregular behavior dependent on the confi guration at large hw indicates a dramatic reduction of the neutron pair correlations at large rotational fr equencies.…”

High-spin state spectroscopy in 165, 166Yb

“…Most recently the interplay between the aligned (quasi-) particles and the shape of the nucleus has been studied experimentally, yielding valuable information for the understanding of nuclear structure at high spins. 3,8,9) Considerable effort has gone into the high-spin spectroscopy of ytterbium nuclei recently 1 0-14), which makes it one of the best studied isotope chains. In this article we study the two well deformed ytterbium isotopes 165yb and 166yb at high spins.…”

Determination of the Spreading Width for the Collective Transition Strength at Finite Temperature

“…This damping mechanism may also explain our inability to observe more discrete-line sequences. With the very sensitive techniques presently available only high-A^ bands, 16 for which the effective density of states is probably low, have been isolated at more than 1 MeV above the yrast band. For other bands the spreading width mixes the decay paths so effectively that selectivity is much reduced.…”