Search

Recent data from the EUROGAM array have revealed dipole transitions linking signature partner superdeformed bands in 194Tl and 195Tl nuclei. Measurements of the decay branching ratios, taken together with the average quadrupole moment of the neighboring superdeformed nuclei, enable the absolute M1 strengths to be determined. From these data and using the strong coupling model, we find that two SD bands in 195Tl are due to the 81st proton being in the [642]5/2+ orbital and four from the six SD bands in 194Tl correspond to a configuration where the intrinsic spins of the single proton and single neutron are aligned.

Two regular dipole gamma -ray cascades have been observed in 194Pb. A comprehensive level scheme related to these structures has been built and first members of rotational bands built on K=8 and K=11 two-proton oblate states have been identified. From the excitation energies, spin values, behaviours of the moments of inertia and alignments, and from the comparison with the isotone 192Hg, multiparticle configurations can be attributed to three high-spin structures of 194Pb built respectively on the 4966 keV, 4334 keV and 6198 keV levels: ( pi 9/2(505) pi 13/2(606))(vi13/2)2, ( pi 9/2(505) pi 13/2(606))(vf5/2vi13/2), ( pi 9/2(505) pi 13/2(606)) (vf5/2(vi13/2)3). Within this interpretation, the regular dipole bands correspond to the presence of two or three i13/2 decoupled neutrons.

The 192Hg nucleus has been produced via the 36S(160Gd, 4n) reaction at a beam energy of 159 MeV. The γ-rays have been detected with the multi-detector array EUROGAM phase 1. The level scheme has been extended up to 10.4 MeV excitation energy and spin 34. Two new structures, composed of competing ΔI = 1 and ΔI = 2 transitions, have been observed and, for the first time in Mercury isotopes, some links with the previously known low-lying states have been established. These experimental results are discussed in terms of mean-field Hartree-Fock plus BCS calculations and the new bands are proposed to originate from deformation-aligned quasi-proton excitations. π(i13/2 * h9/2)kπ=11 and π(h9/2)2kπ=8+ coupled to rotation-aligned quasi-neutrons v(i13/2)n and quasi-proton π(h11/2)2 excitations.