Search

Pb-195 was investigated utilizing the reactions Dy-164(S-36, 5n)Pb-195 and Dy-164(S-34, 3n)Pb-195 at beam energies of 170 and 160MeV respectively. Two new dipole bands which feed into the yrast 25/2(+) state, were found in Pb-195. The connection between the bands and the spherical states was established and thus spins and energies of the involved collective states were determined. The deformation is understood as mainly due to excitations of protons across the Z = 82 shell gap. The observed backbends are interpreted as alignment of i(13/2) neutrons., NR 2015

The yrast superdeformed (so) band in 194Pb has been populated by means of four fusion-evaporation reactions (184W+16O, 184W+17O, 164Dy+34S, 162Dy+36S) lending to different angular momenta and excitation energies in the various compound nuclei. The yields measured for the so band relative to the total yield of the 194Pb channel do not show any dependence on excitation energies and show only a very weak increase with angular momentum. The feeding pattern of the so band in 194Pb is-compared to similar data for so bands in neighbouring nuclei. All these results can be interpreted by the fission process (an important exit channel for all fusion reactions leading to Pb isotopes) which imposes a very low limit in the angular momentum of the Pb residual nuclei.

High-spin structures of the neutron-deficient Xe-117, Xe-118, Xe-120 isotopes have been studied by in-beam gamma-ray spectroscopic techniques. The final nuclei have been identified by means of charged-particle detectors. Collective rotational bands based on the neutron d5/2, 97/2 and h11/2 configurations have been identified in Xe-117. In the even Xe-118 and Xe-120 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 Xe-118, whereas in Xe-120 three such bands were observed. In order to explain these bands, both proton and neutron (h11/2)2 alignments, as well as the shape degree of freedom, have to be invoked. The possible occurrence of a gammaS-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., NR 2015

We report on new results for the decay of the superdeformed (SD) band in 194Pb. No transitions linking the SD structure with the known level scheme of 194Pb could be found, but the feeding intensities into the normal-deformed states are determined and limits on the one-step decay of the SD band are given., NR 2015

NR 2015

High-spin states have been observed in the odd-odd isotope 120Cs in S-32-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 pi-h11/2 x nu-h11/2 band. The experimental data are compared with calculations made within the total routhian surface model and the two-particle plus triaxial rotor model. It is concluded that a significant residual pn interaction rather than triaxiality is responsible for the signature inversion phenomenon in the pi-h11/2 x nu-h11/2 band of 120Cs.(~)[GRAPHICS], NR 2015

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 established. Alignments of both h11/2 protons and neutrons are seen. Of special interest are the alignment frequencies in the (tentative) [422]3/2+ and [404]9/2+ bands which indicate a configuration-dependent proton pairing. Furthermore, the variation of the interaction strength at the first band crossing in the h11/2 bands does not follow the standard cranked-shell-model predictions. This feature is in line with previous systematic observations of alignment processes in high-j intruder bands, and might infer an additional band mixing due to a neutron-proton interaction.(~)[GRAPHICS], NR 2015

The 117I nucleus has been investigated in a high-spin gamma-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., NR 2015

For the first time, excited states of 175Ir have been observed. Remarkably different developments with rotation are found in bands built on the [541]1/2-, [505]11/2-, and [660]1/2+ orbitals. The data are analyzed within the deformed shell model. The pattern of the [505]11/2- band is interpreted as a combined stretching and alignment effect. For the [606]1/2+ band, an extremely strong interaction with the S band results in an almost entirely smeared out alignment process not explained by standard calculations. This feature might indicate a strong residual pn interaction., NR 2015

In a gamma-spectroscopic study, excited states in the very neutron deficient nucleus 121La have been established for the first time. Rotational bands build on the 9/2+[404] and 1/2-[550] Nilsson orbitals are observed up to a maximum spin of tentatively 51/2 h. The experimental results are compared with Total Routhian Surface calculations., NR 2015

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 been established. The alignments of h11/2 protons and neutrons are identified at HBAR-omega-c = 0.35-0.40 MeV in the h11/2 and g7/2 bands whereas an alignment occurs at HBAR-omega-c = 0.29 MeV in the (tentatively) d5/2 band. B(M1)/B(E2) ratios were extracted and contributed to the configuration assignments. The results are interpreted within the cranked mean-field approach., NR 2015

The yrast band of Xe118 has been extended up to tentatively I-pi = 34+ in a heavy-ion in-beam gamma-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., NR 2015

The very neutron deficient nucleus 120Ba has been investigated in a high-spin gamma-spectroscopic study. The yrast band of 120Ba is extended up to spin 22 h and one tentatively assigned negative-parity side band is observed up to spin 15 h. The experimental results are compared with Total Routhian Surface calculations., NR 2015

NR 2015