P. Mason

Charged particle feeding of hyperdeformed nuclei in the A=118?126 region

A breakthrough was recently obtained in the analysis of the so-called Hyper-Long-HyperDeformed (HLHD) experiment made at the EUROBALL-IV γ-detector array (EB). The 64Ni + 64Ni ⇒ 128Ba* fusion reaction was studied at Ebeam = 255 and 261 MeV, reaching the highest angular momentum that the compound nuclei can accommodate. To date no discrete HD rotational bands have been identified. However, rotational patterns in the form of ridge-structures in three-dimensional (3D) rotational mapped spectra are identified with dynamic moments of inertia J(2) ranging from 71 to 1112 MeV-1 in 12 different nuclei selected by charged particle- and/or γ-gating. The four nuclei, 118Te, 124Cs, 125Cs and 124Xe found with moment of inertia J(2)≥100 2 MeV-1, are most likely hyperdeformed, the remaining nuclei with smaller values of J(2), are considered to be superdeformed, in qualitative agreement with recent theoretical calculations.

Hyperdeformed Shapes and Jacobi Transitions in 126Ba

Systematic searches for exotic shapes, hyperdeformation (HD) and Jacobi transitions, have been made in Hf, Nd, Ba, Xe, Sn and Cd nuclei during the last 4 years, guided by theoretical predictions. The most promising results showing patterns of rotational correlations (e.g. 2. order ridges of multiple rotational bands) are found for 126Xe and 126Ba when the very highest multiplicity cascades are selected by various techniques. In particular, the results on 126Ba obtained in 3 different experiments, using both Gammasphere in Berkeley and Euroball IV in Strasbourg are discussed and compared to theoretical predictions and to simulations by a double‐potential statistical model for population and γ‐decay. A very surprising result was obtained in the last experiment at Euroball, in a full month running time, namely that the observed ridge structure depends very sensitively on the bombarding energy, which points to entrance channel effects. The analysis shows that a discrete HD yrast band intensity will be signifi...

Octupole signatures in Ba-124,Ba-125

The γ decay of the nuclei 124,125 Ba has been investigated with the EUROBALL array, using the reaction 64 Ni+ 64 Ni at Ebeam = 255 and 261 MeV. Six new E1 transitions have been found in the nucleus 125 Ba, suggesting a significant role of octupole correlations in the origin of its parity doublets. The J π = 3 − level

Octupole signatures in 124,125Ba

The γ decay of the nuclei 124,125 Ba has been investigated with the EUROBALL array, using the reaction 64 Ni+ 64 Ni at Ebeam = 255 and 261 MeV. Six new E1 transitions have been found in the nucleus 125 Ba, suggesting a significant role of octupole correlations in the origin of its parity doublets. The J π = 3 − level

Octupole signatures in124,125Ba

The γ decay of the nuclei 124,125 Ba has been investigated with the EUROBALL array, using the reaction 64 Ni+ 64 Ni at Ebeam = 255 and 261 MeV. Six new E1 transitions have been found in the nucleus 125 Ba, suggesting a significant role of octupole correlations in the origin of its parity doublets. The J π = 3 − level