P. Ahonen

Signature inversion in 120Cs: Evidence for a residual pn interaction

Abstract High-spin states have been observed in the odd-odd isotope 120Cs in 32S-induced reactions. The previously known band is extended to higher spin and several new bands are identified. Band-head configurations have been inferred by comparing the band properties with known bands in the odd nuclei 121Cs and 121Ba. A remarkable signature inversion is observed in the π h 11 2 ⊗ν h 11 2

Gamma-ray spectroscopy of 110Cd

Abstract The nucleus 110Cd has been studied using the 13C and 18O induced reactions and the NORDBALL multi-detector array. The yrast band was observed to Iπ = 28+ and a large number of side bands were identified. The h 11 2 neutrons were found to play a dominant role in the observed rotational structures. The weakly populated yrast 3187 keV 8+ state is interpreted as arising from the proton g 9 2 −2 configuration. Collective bands, where the band members are connected by ΔI = 1 transitions and where the ΔI = 2 transitions are not observed, are also reported. These bands are interpreted to have prolate configurations involving both the h 11 2 neutrons and the g 9 2 protons. The experimental data are discussed in terms of the total routhian surface and cranked shell model calculations.

Lifetimes of yrast states in 110Cd

Abstract Lifetimes or lifetime limits of 20 yrast levels in 110 Cd have been measured using the recoil-distance method and the NORDBALL array of Compton-suppressed Ge detectors. From the reduced transition probabilities competing rotational and vibrational behaviour of 110 Cd is revealed. Also non-collective states, associated with proton configurations, have been observed.

Alignment processes in 119Cs, 121Cs and 123Cs

Rotational band structures have been observed in the odd-A Cs isotopes 119Cs, 121Cs and 123Cs. The previously known bands have been extended to higher spin values and several new bands have been es ...

Competing proton and neutron alignments in neutron-deficient Xe-nuclei

Abstract High-spin structures of the neutron-deficient 117,118,120 Xe isotopes have been studied by in-beam γ-ray spectroscopic techniques. The final nuclei have been identified by means of charged-particle detectors. Collective rotational bands based on the neutron d 5 2 , g 7 2 and h 11 2 configurations have been identified in 117 Xe. In the even 118 Xe and 120 Xe nuclei several new side bands were observed and the previously known bands were extended. The present level schemes include two positive-parity bands constructed to high spin in 118 Xe, whereas in 120 Xe three such bands were observed. In order to explain these bands, both proton and neutron ( h 11 2 ) 2 alignments, as well as the shape degree of freedom, have to be invoked. The possible occurrence of a γS-band is addressed and a pronounced structural change for more heavy Xe-isotopes is discussed. All negative-parity side bands are interpreted in terms of proton two-quasiparticle excitations. The experimental data are compared with total routhian surface calculations.

High-spin states in 121Ba and deformation-dependent alignments

The high-spin structure of 121Ba has been investigated by in-beam gamma-ray spectroscopic techniques. Rotational bands based on the h11/2, g7/2 and tentatively d5/2 quasineutron configurations have ...

Evidence for band termination in118Xe

The yrast band of118Xe has been extended up to tentativelyIπ = 34+ in a heavy-ion in-beam γ-spectroscopic study using the NORDBALL detector array. A band crossing is observed at the highest spins and interpreted within the Modified Oscillator Model as a transition to a terminating band.

Neutron and protonh11/2 alignment effects in121La

In a γ-spectroscopic study, excited states in the very neutron deficient nucleus121La have been established for the first time. Rotational bands built on the 9/2+[404] and l/2−[550] Nilsson orbitals are observed up to a maximum spin of tentatively 51/2ħ. The experimental results are compared with Total Routhian Surface calculations.

High spin states of120Ba

The very neutron deficient nucleus120Ba has been investigated in a high-spin γ-spectroscopic study. The yrast band of120Ba is extended up to spin 22ħ and one tentatively assigned negative-parity side band is observed up to spin 15ħ. The experimental results are compared with Total Routhian Surface calculations.

Shape coexistence in 117 I

The117I nucleus has been investigated in a high-spin γ-spectroscopic study using the NORDBALL detector array. The observed level structures are interpreted as resulting from coexisting collective prolate and oblate as well as non-collective oblate shapes.