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| Home > Publications database > Beta decay studies of shell model aspects of N=83 and 84 nuclei |
| Book/Report | FZJ-2018-03634 |
1991
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
Jülich
Please use a persistent id in citations: http://hdl.handle.net/2128/19043
Report No.: Juel-2529
Abstract: It is known since some time that the $^{164}_{64}$Gd$_{82}$ nucleus displays several features characteristic of a doubly closed nucleus, in some respects similar as $^{208}$Pb. The nuclei in the neighbourhood of such doubly closed cores are well described in terms of the spherical shell model. Shell model analyses in heavynuclei have originally been developed in the $^{208}$Pb region, and they were particularly successful when the single particle energies and the two-body nucleon-nucleon interactions were extracted from experimental data. More recently, the empirical shell model has also been applied with good success to the nuclei around $^{146}$Gd. In contrast to $^{208}$Pb, which is a stable nucleus, the neutron deficient $^{146}$Gd lies far off the stability valley. Consequently, the spectroscopic data an the nuclei around $^{146}$Gd originate to a large extend from in-beam $\gamma$-ray measurements following fusion-evaporation reactions where preferably the levels at the yrast line are excited. This often presents a limitation since many specific basic excitations that are needed as input for the shell model analysis lie above the yrast line and therefore are still largely unknown. The only means to identify above-yrast levels in these nuclei is to excite them in $\beta$-decay. For allowed transitions, the ß-decay directly locates specific configurations in the daughter nucleus, which in their $\gamma$-decay will often populateother above-yrast configurations. In the present thesis I will report results obtained from $\beta$-decay studies of nuclei above $^{146}$Gd, namely the decays of the 1/2$^{+}$ and 11/2$^{- }$ activities of the N=82 nuclei $^{147}$Tb and $^{149}$Ho, and the $\beta$-decay branch of the 27/2$^{-}$ 3-quasiparticle isomer at 3 MeV excitation in $^{149}$Dy. These decay studies have been carried out at accelerators with a separator on-line, where the activity, after extraction from the production target, is mass separated in a magnetic sector field and in general deposited an a transport tape that is periodically moved to the measuring position. The data reported here have been obtained at the GST-, the ISOCELE II- at Orsay, and the ISOLDE-CERN on-line mass separators. [...]
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