[en] Heavy neutron-rich nuclei close to N = 126 were produced by fragmentation of a 1A GeV ²⁰⁸Pb beam at the FRS at GSI. The β-decay half-lives of 7 nuclides have been determined using a novel numerical analysis method. The half-lives of ^202,199Ir, ^200,199Os and ¹⁹⁶Re are reported for the first time. The comparison of the data with model calculations provides indications on the importance of first-forbidden transitions on the β-decay of nuclei around N = 126 and Z < 82. (orig.)

[en] A large amount of experimental information was obtained on heavy neutron-rich nuclei in the Hf-Hg region during the last decade. In the majority of the cases these nuclei were populated in relativistic energy fragmentation and studied via isomeric and β decays. In addition, deep-inelastic studies gave information to nuclei close to stability. The experimental data were used to establish the sign of quadrupole deformation, prolate or oblate. In the present paper this information is compared with two global theoretical calculations, one which is constrained to axial symmetry and one which considers triaxiality. The prolate-oblate transitional region was reached for (Z=76) Os and Ir (Z=77), as proved by the observation of oblate isomeric states in ^197,198,199Os and ²⁰¹Ir. For Ta (Z=73) and W (Z=74) isotopes no clear evidence of oblate deformation exists so far, with ¹⁹²W and ¹⁸⁹Ta being the most neutron-rich isotopes with spectroscopic information.

[en] Nuclear spectroscopic information for known nuclides of mass number 199 (Os,Ir,Pt,Au,Hg,Tl,Pb,Bi,Po,At,Rn,Fr) with Z = 76 to 87 and N = 123 to 112 have been evaluated and presented together with adopted energies and Jπ of levels in these nuclei. No excited state data are available for ¹⁹⁹Os and ¹⁹⁹Fr, and very little information is available for levels in ¹⁹⁹Ir, ¹⁹⁹Rn and ¹⁹⁹At. The decay of ¹⁹⁹Ir to ¹⁹⁹Pt has not been studied. The decay of the 90-min activity of ¹⁹⁹Pb to ¹⁹⁹Tl is known in detail but remains unpublished in the open literature, while the decay of the 12.2-min isomer remains mostly unknown. The decays of the two activities of ¹⁹⁹Tl to ¹⁹⁹Pb are not known as separate decay scheme for each of the activities, thus only a composite decay scheme is presented. Similar is the case for the decay of the two activities of ¹⁹⁹Po to ¹⁹⁹Bi. In (³He,d) and (α,t) studies for ¹⁹⁹Au, disagreements are found between two independent contemporary studies. The most detailed structure known is for ¹⁹⁹Pb with five magnetic-rotational (MR) dipole bands together with many other dipole bands which are of probable multi-quasiparticle nature. This work supersedes previous evaluations of A = 199 published in update mode by 1994Ar13; as full A-chain updates by 1988Sc02, 1978Ha12 and 1971Le37; and a mid-stream update of ¹⁹⁹Pb nuclide by 2001Si44

[en] Very neutron-rich nuclei near the A = 195 r-process waiting point were produced as projectile fragments from a ²⁰⁸Pb primary beam at GSI, Darmstadt, by cold fragmentation. After in-flight separation, the fragments were implanted in an active catcher, and time correlations to the subsequent beta-decay were established. Due to the periodic operation cycles of the synchrotron, providing the primary beam, the background shows a complex time structure, which prevents applying well established analytical methods to extract the half-life information. A new mathematical analysis method has been developed, which is based on a Monte Carlo code, simulating the time sequence of implantation and beta detection according to the experimental conditions, leaving the beta lifetimes and the beta detection efficiency as free parameters. In addition, both the analysis of the experimental data and the simulation were performed in time-reversed sequence. The ratio of forward/backward time spectra contains the information of the 'true' fragment-beta correlations. Half-lives were obtained from two-dimensional fits of the measured and simulated ratios of time correlations in forward- and backward-time direction by the least-squares method, being the lifetime and the beta-detection efficiency the two fitting parameters. Half-lives of 8 heavy neutron-rich nuclei approaching the r-process waiting point A = 195 have been determined. (authors)

[en] Heavy neutron-rich nuclei were populated via the fragmentation of a E/A=1 GeV ²⁰⁸₈₂Pb beam. Secondary fragments were separated and identified and subsequently implanted in a passive stopper. By the detection of delayed γ rays, isomeric decays associated with these nuclei have been identified. A total of 49 isomers were detected, with the majority of them observed for the first time. The newly discovered isomers are in ^204,205₈₀Hg, ^{201,202,204,205}₇₉Au, ^197,203,204₇₈Pt, ^195,199-203₇₇Ir, ^193,197-199₇₆Os, ¹⁹⁶₇₅Re, ^190,191₇₄W, and ¹⁸⁹₇₃Ta. Possible level schemes are constructed and the structure of the nuclei discussed. To aid the interpretation, shell-model as well as BCS calculations were performed.