Triple configuration coexistence in 44 S

The neutron-rich N=28 nucleus S44 was studied using the two-proton knockout reaction from Ar46 at intermediate beam energy. We report the observation of four new excited states, one of which is a strongly prolate deformed 4 + state, as indicated by a shell-model calculation. Its deformation originates in a neutron configuration which is fundamentally different from the "intruder" configuration responsible for the ground-state deformation. Consequently, we do not have three coexisting shapes in S44, but three coexisting configurations, corresponding to zero-, one-, and two-neutron particle-hole excitations. � 2011 American Physical Society

Complex band interactions in 170Er

Inelastic excitation of 170Er by a 238U beam, studied at near-barrier energies, has led to the observation of unusual features in rotational bands built on low-lying vibrations. The population of the high-spin members of the Kπ=0+, β-vibrational band is enhanced due to mixing with the Kπ=2+, γ-vibrational band at spin 4+. Strong mixing of the Kπ=0+ band with a rotationally aligned 2 qp band results in this band losing its β-vibrational character and in a rapid gain in spin alignment leading to a crossing with the ground-state band between spins 2O+ and 22+. The low-lying Kπ=3+ band also is populated. It subsequently decays to both the γ-vibrational and the ground-state bands. The occurrence of appreciable K-forbidden E2 transitions from the Kπ=3+ to the ground-state band is attributed to mixing with the Kπ=2+ band, caused by the interaction between the quadrupole γ-vibrational and the hexadecapole vibrational motions

Effective charge of the [pi]h11/2 orbital and the electric field gradient of Hg from the yrast structure of 206Hg

The γ-ray decay of excited states of the two-proton hole nucleus, 206Hg, has been identified using Gammasphere and 208Pb+238U collisions. The yrast states found include a T1/2 = 92(8)ns 10+ isomer located above the known 5- isomer. The B(E2;10+→8+) strength is used to derive the quadrupole polarization charge induced by the h11/2 proton hole. Also, the implied quadrupole moment has been used to provide an absolute scale for the electric field gradient of Hg in Hg metal

Cluster Interpretation of Properties of Alternating Parity Bands in Heavy Nuclei

The properties of the states of the alternating parity bands in actinides, Ba, Ce and Nd isotopes are analyzed within a cluster model. The model is based on the assumption that cluster type shapes are produced by the collective motion of the nuclear system in the mass asymmetry coordinate. The calculated spin dependences of the parity splitting and of the electric multipole transition moments are in agreement with the experimental data.Comment: 29 pages, 10 figure

Odd-even staggering in the πg9/2vg9/2 band in 72Br

High-spin positive-parity states in 72Br have been studied using the 16O+58Ni reaction. The πg9/2vg9/2 decoupled band in 72Br has been observed up to ∼10 MeV excitation energy and the expected odd-even staggering has been delineated. A larger signature splitting is observed for this band in 72Br than in the same collective structures in the heavier 74,76,78Br. No signature inversion at low spin is observed for this band in 72Br, in contrast to the heavier isotopes, 74,76,78Br, in which signature inversion is observed below ∼10(Latin small letter h with stroke sign). The observations are in general agreement with theoretical models in this mass region which predict no signature inversion for nuclei with less than 39 protons and neutrons

Structure of the Odd-A, Shell-stabilized nucleus No102253

In-beam γ-ray spectroscopic measurements have been made on No102253. A single rotational band was identified up to a probable spin of 39/2, which is assigned to the 7/2+[624] Nilsson configuration. The bandhead energy and the moment of inertia provide discriminating tests of contemporary models of the heaviest nuclei. Novel methods were required to interprete the sparse data set associated with cross sections of around 50nb. These methods included comparisons of experimental and simulated spectra, as well as testing for evidence of a rotational band in the γγ matrix