Population of a low-spin positive-parity band from high-spin intruder states in 177Au : The two-state mixing effect

The extremely neutron-deficient isotopes 177,179Au were studied by means of in-beam γ-ray spectroscopy. Specific tagging techniques, α-decay tagging in 177Au and isomer tagging in 179Au, were used for these studies. Feeding of positive-parity, nearly spherical states, which are associated with 2d3/2 and 3s1/2 proton-hole configurations, from the 1i13/2 proton-intruder configuration was observed in 177Au. Such a decay path has no precedent in odd-Au isotopes and it is explained by the effect of mixing of wave functions of the initial state

The 257 MeV 19/2/sup -/ two-phonon octupole state in /sup 147/Gd

The half-life of the (vf/sub 7/2/*3/sup -/*3/sup -/)/sub 19/2-/ two- phonon octupole states at 2.572 MeV in /sup 147/Gd was measured as T /sub 1/2/=0.37(8) ns, which gives a transition strength of 52(15) WU for the 1525 keV E3 transition to the 0.997 MeV (vf/sub 7/2/*3/sup -/) /sub 13/2+/ one transition to the 0.997 MeV ( nu f/sub 7/2/*3/sup -/) /sub 13/2+/ one phonon excitation. The nu i/sub 13/2/ admixture in the 13/2/sup +/ one-phonon state, as well as the dominant pi h/sub 11/2/d /sub 5//sup -1/2/ component of the /sup 146/Gd 3/sup -/ state give rise to large anharmonicities for the two-phonon excitation. An estimate of the energy shifts based on empirical coupling matrix elements gives 2.66 MeV excitation for the 19/2/sup -/ two-phonon state, in good agreement with the observed energy of that state. (9 refs)

Decay of mass-separated \u3csup\u3e189m\u3c/sup\u3eHg (8.7 min) and \u3csup\u3e189g\u3c/sup\u3eHg (7.7 min) to \u3csup\u3e189\u3c/sup\u3eAu

The decays of 189Hg (8.7 min; Jπ = 13/2+) and 189Hg (7.7 min; Jπ = 3/2-) have been studied with mass-separated sources from the UNISOR facility. Multiscaled spectra of γ-rays, X-rays, and conversion electrons, as well as γγt, γXt, eyt, and eXt coincidences were obtained. Decay schemes have been constructed incorporating \u3e 95% of the decay intensities assigned to the high-spin and low-spin decays. The γ-ray gated conversion-electron spectra permitted the determination of 119 conversion-electron subshell ratios. Portions of the level scheme bear a remarkable resemblance to the heavier and lighter odd-mass Au isotopes. An extensive band of states is observed built upon the h9/2 intruder state at 325 keV. This band is markedly different from the corresponding bands in 187Au and 185Au, indicating a major change in the cores, i.e. between 188Pt and 186,184Pt. Evidence for oblate-hole-prolate-particle symmetry in 189Au is discussed. Completeness of complex decay schemes far from stability is addressed

Nuclear systematics far from the line of beta stability: The low-lying excited states of \u3csup\u3e185,187,189\u3c/sup\u3eAu

The low-lying excited-state systematics of 185,187,189Au are presented. These are based mainly on the authors\u27 radioactive decay studies of 185,187,189Hg, some details of which are reported. All of the band structures seen in 189Au and the heavier Au isotopes are found to have counterparts in 185,187Au. This is consistent with the systematics of high-spin states in the odd-mass Au isotopes seen using in-beam reaction spectroscopy. It is at variance for 185Au, however, with the only previously published radioactive decay study of the low-medium-spin states in that nucleus. Also, recent optical hyperfine spectroscopy data have shown that 185Au, in contrast to the heavier Au isotopes, has a large ground-state deformation. The earlier results which showed a decisive break in the systematics at 185Au might be taken to be consistent with this onset of ground-state deformation, but the authors\u27 data clearly show that the systematic patterns seen for bands in 189Au and the heavier odd-mass Au isotopes persist even into 185Au. © 1988 IOP Publication Ltd

Beta-decay of light rare-earth\u3csup\u3e130, 132\u3c/sup\u3ePr and\u3csup\u3e132, 134\u3c/sup\u3ePm nuclei

Gamma-ray spectra of neutron-deficient isotopes of130, 132Ce and132, 134Nd have been investigated from the β-decay of130,132Pr and132,134Pm new gamma-bands of states were identified and the systematic trends are presented. © 1987 Springer-Verlag