No abstract available

No abstract available

[en] In-beam γγ coincidence data have been collected for ¹⁸⁶Pb by combining the JUROGAM Ge-detector array and the GREAT spectrometer with the RITU gas-filled recoil separator for recoil-decay tagging measurements. In addition to the known prolate yrast band in ¹⁸⁶Pb, these data have enabled a new low-lying side band to be identified. Based on the analysis of its decay pattern and comparison with Interacting Boson Model (IBM) calculations, the new band is associated with an oblate shape

[en] This measurement represents the first observation of a non-yrast band in the ¹⁸⁶Pb nucleus by employing the Recoil-Decay Tagging (RDT) technique. Previously known yrast levels have been confirmed and the band is extended up to level I^π=(16⁺). (orig.)

[en] Recoil-decay tagging technique has been employed in the study of non-yrast states in 186Pb. High quality γγ-coincidence data have revealed three new bands and the yrast band has been extended up to Iπ=20+. A low-lying non-yrast band provide evidences for an oblate structure

[en] High-spin states in ³⁶₇₆Kr₄₀ have been populated in the ⁴⁰Ca(⁴⁰Ca,4p)⁷⁶Kr fusion-evaporation reaction at a beam energy of 165 MeV and studied using the Gammasphere and Microball multidetector arrays. The ground-state band and two signature-split negative parity bands of ⁷⁶Kr have been extended to ∼30(ℎ/2π). Lifetime measurements using the Doppler-shift attenuation method show that the transition quadrupole moment of these three bands decrease as they approach their maximum-spin states. Two signatures of a new rotational structure with remarkably rigid rotational behavior have been identified. The high-spin properties of these rotational bands are analyzed within the framework of configuration-dependent cranked Nilsson-Strutinsky calculations

[en] Two of the four known rotational bands in ⁷⁵Rb were studied via the ⁴⁰Ca(⁴⁰Ca,αp)⁷⁵Rb reaction at a beam energy of 165 MeV. Transitions were observed up to the maximum spin I_max of the assigned configuration in one case and one-transition short of I_max in the other. Lifetimes were determined using the residual Doppler shift attenuation method. The deduced transition quadrupole moments show a small decrease with increasing spin, but remain large at the highest spins. The results obtained are in good agreement with cranked Nilsson-Strutinsky calculations, which indicate that these rotational bands do not terminate, but remain collective at I_max.

[en] Lifetimes have been deduced in the intermediate/high-spin range for the three known rotational bands in ⁷³Kr and the T=0 band in ⁷⁴Rb using the residual Doppler shift method. This has enabled relative transition quadrupole moments to be studied for the first time in triaxial nuclei as a function of spin. The data suggest that the additivity principle for transition quadrupole moments is violated, a result that is in disagreement with predictions from cranked Nilsson-Strutinsky and cranked relativistic mean-field theory calculations. The reasons for the discrepancy are not understood but may indicate that important correlations are missing from the models

[en] A new setup has been designed to perform Coulomb excitation experiments with fragmentation beams at intermediate energy and to measure at the same time conversion electrons from isomeric states populated in the fragmentation reaction. The newly designed setup is described and experimental results from a first experiment are shown. Radioactive even-even nuclei in the mass region A≅70 close to the N=Z line were Coulomb excited after fragmentation of an intense primary ⁷⁸Kr beam and selection in flight with the LISE3 spectrometer at GANIL. The γ rays emitted after Coulomb excitation were detected in an array of four large segmented HPGe clover detectors in a very close geometry. The scattered ions were identified in a stack of highly segmented annular silicon detectors combined with a time-of-flight measurement using beam tracking detectors. Conversion electrons from isomeric 0₂⁺ states decaying via electric monopole transitions were detected in an array of segmented cooled silicon detectors surrounding a telescope of plastic scintillators. Reduced transitions probabilities B(E2;0₁⁺→2₁⁺) were deduced for several stable and radioactive nuclei

[en] Four previously known rotational bands in ⁷⁶Rb have been extended to moderate spins using the Gammasphere and Microball γ ray and charged particle detector arrays and the ⁴⁰Ca(⁴⁰Ca, 3pn) reaction at a beam energy of 165 MeV. The properties of two of the negative-parity bands can only readily be interpreted in terms of the highly successful Cranked Nilsson-Strutinsky model calculations if they have the same configuration in terms of the number of g_9/2 particles, but they result from different nuclear shapes (one near-oblate and the other near-prolate). These data appear to constitute a unique example of shape coexisting structures at medium spins.