[en] Low-lying proton-based intruder states have been observed in the odd-mass isotopes ^189,191,193Pb in experiments at the RITU gas-filled recoil separator. The identification has been performed by observing the fine structure in the α decay of the parent ^193,195,197Po nuclei in prompt coincidence with conversion electrons and γ rays in the daughter lead isotopes. Along with the literature data these results establish a systematics of intruder states in the odd-mass lead isotopes from ¹⁹⁷Pb down to ¹⁸⁵Pb. Interpretation of these states involves the coupling of the 1i_13/2 or 3p_3/2 odd neutron to the 0⁺ state in the oblate minimum in the even-mass lead core. Conversion coefficients have been determined for some of the transitions, revealing mixing between the coexisting states. The experimental results are compared to potential energy surface calculations

[en] Excited states in the nucleus ¹⁹¹Pb have been investigated by in-beam γ-ray spectroscopic techniques using the Gammasphere array. The reaction ¹⁷³Yb(²⁴Mg,6n) at a beam energy of 134.5 MeV was used to populate states of ¹⁹¹Pb. The level scheme of ¹⁹¹Pb has been extended up to 5.1 MeV excitation energy and spin 45/2. The lower part (below ∼2.3MeV) presents the general features common in all odd-mass Pb isotopes, i.e., spherical states built on the 13/2⁺ isomer, with bandlike structures that follow weak-coupling expectations. In the upper part of the level scheme two dipole bands are observed with bandhead energies of ∼2.512 and 2.291 MeV. A comparison of dipole band 1 with the strongest negative-parity dipole bands in the heavier odd-mass Pb isotopes reveals striking similarities. The spherical states are interpreted as the coupling of the i_13/2 neutron hole to the yrast states in the even-mass ¹⁹²Pb core. The dipole bands are interpreted as M1 cascades which arise from the coupling of two protons in high-j orbitals above the Z=82 gap to neutron holes in the i_13/2 orbital. copyright 1998 The American Physical Society

No abstract available

[en] This evaluation presents spectroscopic data and level schemes from radioactive decay and nuclear reactions for nuclei with mass number A=191. A salient topic includes the recent experimental results on superdeformed bands observed in ₁₉₁Au, ¹⁹¹Hg, and ¹⁹¹Tl

[en] Levels of ¹⁹¹Tl were populated by the β decay of ¹⁹¹Pb. Singles gamma spectra as well as γ-γ-time coincidences were accumulated for ¹⁹¹Pb mass-separated sources produced via the ¹⁵⁰Sm + ⁴⁸Ti reaction. Fifteen γ transitions were assigned to the ¹⁹¹Tl level scheme, thus providing additional information about this incompletely studied nucleus far from stability. (author)

[en] The ¹⁹¹Pb isotope, produced through different A (b,xn) ¹⁹¹Pb reactions, where b stands for nuclei such as ¹⁶O, ²⁰Ne, and ³¹P, is studied. The half-life of some excited levels being greater than 10 ns, the recoil catcher method is suitable to look into the de-excitation γ ray and conversion electron spectra of these states. The conversion coefficients are deduced and e^--γ and γ-γ coincidence measurements lead to the part of the level scheme de-exciting these isomers. This level scheme is compared to theoretical predictions obtained through a microscopic calculation in a three quasi-particle approximation, using a surface delta interaction with a reduced pairing component. The conclusions are very similar to those previously obtained for ¹⁹³Pb

[en] Shape coexistence in the nuclei Pb^182-192 is analyzed with the Hartree-Fock-Bogoliubov approach and the Gogny force. Good agreement with the experimental energies is found for the coexisting spherical, oblate, and prolate states. Contrary to the established interpretation, it is found that the low-lying prolate and oblate 0⁺ states are predominantly characterized by neutron correlations whereas the protons behave, in general, rather as spectators than playing an active role

[en] Prompt, in-beam γ rays in coincidence with evaporation residues were measured in the ^164,166Er + 164 MeV ³²S reactions. A level scheme built on the 13/2⁺ isomer has been deduced from four transitions assigned to ¹⁹¹Pb. The states in ¹⁹¹Pb are interpreted in terms of a weak coupling of the odd i_13/2 neutron-hole to the spherical states in the even-mass ¹⁹²Pb core. (orig.). With 4 figs

[en] We report here on the measurement of isotope shift and hyperfine splitting of ^{190,191,193,197}Pb for the 723 nm atomic optical transition. Detailed analysis of the optical data has been done by combining them with the available muonic and electronic X-ray isotope shift data. The magnetic dipole moments and the electric quadrupole moments of the odd isotopes have been extracted from the hyperfine coupling constants of the atomic states involved in the optical transition used. (orig.)

[en] The ¹⁹¹Pb isotope, produced through different A(b,xn)¹⁹¹Pb reactions, where b stands for nuclei as ¹⁶O, ²⁰Ne and ³¹P, is studied. The half-lives of some excited levels being greater that 10 ns, the recoil catcher method is suitable. The study of the de-excitation γ ray and conversion electron spectra, together with γ - γ and γ - e^- coincidence measurements leads to a level scheme. The characteristics are similar to those observed in ¹⁹³Pb. This experimental level scheme is compared to the theoretical one obtained through a microscopic calculation in a three quasi-particle approximation, using a surface delta interaction with a reduce pairing component. The conclusions reached are very close to those for the ¹⁹³Pb study. (authors)