194Pt(12C, 12C′) reaction and the triaxial-rotor model
Abstract
Elastic and inelastic scattering differential cross sections for the 194Pt(12C, 12C′) reaction at a bombarding energy of 78 MeV have been measured. Data have been obtained for 0+, 2+, 4+, and 2+′, states in 194Pt. The data have been analyzed using a rigid asymmetric-rotor model in coupled-channels reaction calculations. It is found that satisfactory fits to all data can be obtained but only if the hexadecapole deformation is included in the asymmetric-rotor model.
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Cited by (18)
Nuclear Data Sheets for A=194
2021, Nuclear Data SheetsExperimental nuclear structure and decay data are evaluated for all of 14 known nuclides of mass 194 (Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, Po, At, Rn). Detailed evaluated spectroscopic information is presented for each reaction and decay experiment, and by combining all the available data, recommended values are provided for energies, spins and parities and half-lives of levels, together with energies, branching ratios and multipolarities of gamma radiations from the levels, and characteristics of beta and alpha radiations in radioactive decays. No excited states have yet been identified in 194Ta, 194W, and 194Rn. Only limited spectroscopic data are available for 194Re, with a 45−μs isomer identified, but its absolute energy yet to be determined. Only two levels at unknown absolute energies are reported for 194At, both of which are isomeric but neither can be unambiguously identified as the ground state. Data are scarce for 194Os, 194Bi and 194Po, while 194Pt, 194Au, 194Hg, 194Tl and 194Pb are well studied through decays and reactions. For 194Ir, although a major (n, γ), E=thermal study and two particle-transfer studies provide large amounts of spectral data, still several problematic issues are found in the assignment of multipolarities for the secondary gamma transitions in the (n, γ) study by 2008Ba25, 1998Ba85 and 1998Ba42, all from the same group. Some issues have been resolved by the evaluators, but we suggest that further experimental work is needed on 194Ir structure to resolve standing issues, and verify the conclusions made by 2008Ba25. Our attempt to contact the prime authors of the 2008Ba25 paper was not successful. The present work supersedes all the earlier evaluations of A=194 nuclides by 2006Si17, 1996Br26, 1989Si01 and 1972Au11.
Nuclear Data Sheets for A = 194
2006, Nuclear Data SheetsNuclear spectroscopic information for known nuclides of mass number 194 (Re,Os,Ir,Pt,Au,Hg,Tl,Pb,Bi, Po,At) with Z = 75 to 85 and N = 119 to 109 have been evaluated and presented together with adopted energies and Jπ of levels in these nuclei. No excited state data are yet available for 194Re and 194At. Many superdeformed structures are known in A = 194: three SD bands in 194Hg, two of which are connected to the normal-deformed structures; six SD bands in 194Tl; and three SD bands in 194Pb, one of which is connected to the normal-deformed structure. In addition four magnetic-rotational (MR) dipole bands are known in 194Pb together with many other dipole bands which are probable multi-quasiparticle structures. This evaluation supersedes previous full evaluations of A = 194 published by 1996Br26, 1989Si01, 1977Ha46 and 1972Au11.
Nuclear data sheets for A = 194
1996, Nuclear Data SheetsAbstract:Experimental data pertaining to all nuclei with mass A = 194 were evaluated. Level schemes from both radioactive decay and reaction studies are presented, along with associated tables of experimental data and adopted properties for levels and γ rays. The literature cutoff date for this revision is September 30, 1996. This revision replaces 89SiO1. Extensive high-spin experiments using large gamma-detector arrays have revealed superdeformed structures in194Hg (three SD bands: Yrast and pair of excited signature partners),194Tl (six SD bands: Three pairs of signature partners), and194Pb (three SD bands: Yrast and pair of excited signature partners). For yrast bands (SD-1) in194Hg and194Pb, connecting transitions between the SD band and normal bands have recently (96Kh04, 96Lo12,96Br07) been reported. Several dipole (oblate) bands in194Pb, some based on high-K (oblate) states have been reported from similar in-beam γ-ray experiments. New γγ coincidence measurements (93Ko59, 94KoZQ) using the193Ir(n,γ) reaction helped to place several transitions in the level scheme and established the 31.85-ms194Ir isomer at 147.078 KeV 5. Results from the first study of the193Ir(d,p) reaction (94Ga30) agree with those from (n,γ). Unpublished (95TeZZ) γγ coincidence results (using HERA, an array of 20 intrinsic germanium detectors) revealed a new level in194Pt at 1737.4 KeV. It also provided correct placement in the decay scheme for many γ rays from194Au ϵ decay. Recent measurements (92Hu04) of the α-decay chain202Fr–196At–194Bi confirm the existence of194Bi isomers, and show population to previously unknown levels at 218 and 396 KeV in194Bi.Cutoff Date:All data received by September 30, 1996 were evaluated.General Policies and Organization of Material:See the January issue of Nuclear Data Sheets.Acknowledgments:Evaluators wish to thank R.R.P. Teixeira (95TeZZ) for making available their unpublished data on194Au ϵ decay.General Comments:The analysis of γ-ray data is described in detail in 86BrZQ. The γ-ray energies given by various authors were fit to a level scheme for each data set through a weighted least-squares analysis. The scales for the corresponding intensities, which were assumed to be linearly related, were adjusted using the methods of Tepel (80TeZW) and Lederer (92LeZJ). Uncertainties of absolute γ-ray intensities were determined using the method of Browne (86Br21).
Transition densities for γ-unstable nuclei
1989, Nuclear Physics, Section AA prescription to construct transition densities for the inelastic excitation of γ-unstable nuclei is introduced. The presence in the spectra of two low-lying 2+ states whose transition densities have significantly different radial dependences provides an opportunity for testing unusual blendings of the Coulomb and nuclear components in the coupling. An extension of the formalism to construct transition densities to the members of the excited β-band is also given.
Nuclear data sheets for A = 194
1989, Nuclear Data SheetsSpectroscopic data for known nuclei of A=194 (Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, Po, At) have been evaluated and presented with adopted level properties and associated γ rays. No experimental data exist on 194Hf and 194W, but amongst other nuclides in heavy mass region these have been included and nuclear structure calculations by 85Ro21, 85He14, 84Sa16, and 83Ba47. Except for the isotopic identification, nothing much is known about the level structure of 194Bi, 194Po, and 194At.
Since the 1997 evaluation of A=194 (77Ha46), the following are the main additions to the present revision: excited state data are now available for 194Os through a 2-neutron transfer reaction and for 194Tl from 194Pb ɛ decay and (Hl,xnγ) study. New high spin data for 194Au, 194Hg, 194Tl, and 194Pb from in—beam γ—ray studies reveal band structures. A new isomer is tentatively identified in 194Bi; its ɛ decay reveals a low lying 0+ state as the first excited state in 194Pb. From α decay studies, 194At isotope has been identified.
Further experimental work is needed in the following causes: in a recent neutron capture work on 194Ir, only about 60 of the 900 reported γ rays can be placed in a level scheme, although a large number of levels are indicated from primary γ rays. The existence of isomerism in 194Bi remains to be confirmed through a more detailed study of 194Bi ɛ decay. The radioactive decays of 194Os (6.0 y), 194Ir (31.85 ms), and 194Tl (33.0 min and 32.8 min) need more definitive work. The newly discovered first excited state in 194Pb with Jπ=0+ has been interpreted as the starting member of a collective band; however, high—spin members of such a band have not yet been found in the (hl,xnγ) studies of 194Pb.
Elastic and inelastic scattering of 120 MeV <sup>18</sup>O from <sup>208</sup>Pb and the spin alignment of the 2<sup>+</sup> state of <sup>18</sup>O
1983, Nuclear Physics, Section AThe elastic and inelastic scattering of 18O ions at 120 MeV from a target of 208Pb have been studied. Cross sections for excitation of the 2+ state at 1.982 MeV in 18O and of the 3− state at 2.61 MeV in 208Pb were measured. In addition, the populations of the m-substates for the 18O excitation were deduced from the Doppler-broadened line shapes. The data were subjected to a coupled-channels analysis using either Woods-Saxon or folding-model potentials. In addition, the 18O excitation was found to be described very well by use of a semi-microscopic model. The analyses consistently indicated the presence of a positive static hexadecapole moment of several e · fm4 for the 2+ state of 18O. The m-substate population distributions were found to be better fitted if a vector spin-orbit coupling was introduced for the 2+ state of 18O with a sign opposite to that for the nucleon-nucleus case.
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Work supported by NSF Grant PHY 76-08788 and by Oak Ridge Associated Universities, Inc.
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Operated by Union Carbide Corp. for the US Department of Energy.