A. J. Kreiner

Alternating parity bands in doubly odd 218Ac129 and octupole instability in the light actinide region

Abstract High-spin states of doubly odd 218 Ac1 129 have been investigated using in-beam α, γ and conversion electron spectroscopy techniques through the 209 Bi( 12(13) C,3(4)n) fusion-evaporation reactions. The level scheme of 218 Ac shows three interconnected, alternating parity structures, each one linked by strong El transitions. Two of these bands are strikingly similar to the known scheme of the isotone 217 Ra and this analogy is shown to persist for the pair 220 Ac, 219 Ra. The relation between the structure of 218 Ac and its neighbors is thoroughly discussed showing that the first signals of octupole collectivity appear for N = 129.

Pseudo-spin flip in doubly decoupled structures and identical bands

Abstract Unfavored components of doubly decoupled bands are reported for the first time. They can be interpreted as having the pseudo-spin flipped relative to the orientation in the favored components, i.e. antialigned with respect to the rotation axis. In addition, the differences in consecutive transition energies along the favored and unfavored sequences are strikingly similar among them up to Iπ = 15+and 14+ respectively. This feature arises from a cancellation of differences in alignments and moments of inertia.

Spectroscopy of 215Rn86

The yrast level structure of 215,216Rn has been studied using in beam spectroscopy α − γ − γ coincidence techniques mainly through the 207Pb(18O, 2α2n) and 208Pb(18O, 2α2n) reactions in the 91–93 MeV energy range, using the 8π GASP‐ISIS spectrometer at Legnaro. The obtained low lying level scheme of 215Rn does not exhibit the alternating parity structure observed in their heavier known isotones 216Fr, 217Ra and 218Ac. The level scheme of 216Rn resulting from this study shows >From this result, the lightest nucleus showing evidence for reflection asymmetry is 216Fr defining one lowest‐mass corner for this kind of phenomenon as N⩾129 and Z⩾87.

High-spin states in odd-odd 168Tm

High‐spin states in 168Tm were investigated by means of γ‐ray spectroscopy techniques using the GASP multidetector array. Rotational bands have been established and identified in terms of their configurations.

Doubly decoupled bands in176, 178Re

High spin states in176, 178Re have been studied using in-beam γ and e− spectroscopy techniques through heavy ion induced fusion reactions. A ΔI=2 rotational band of doubly decoupled type has been identified in each isotope.