Pairing in nuclei near the proton-drip line
Abstract
Pairing properties of nuclei close to the proton-drip line are studied within the framework of the quasiparticle lagrangian method. It is shown that the density dependence of effective pairing forces plays a significant role in the experimentally discovered effect of increase of proton pairing near the proton-drip line.
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Nuclear Structure and Decay Data for A=167 Isobars
2023, Nuclear Data SheetsExperimental nuclear spectroscopic data are compiled and evaluated for 17 known nuclides of mass 167 (Sm, Eu, Gd, Tb, Dy, Ho, Er Tm, Yb, Lu, Hf, Ta, W, Re, Os, Ir, Pt), 23 years after the previous full evaluation by 2000Ba65. Detailed information is presented for each reaction and decay experiment. Combining all the available data, recommended values are provided for energies, spins and parities, and half-lives of levels, with energies, branching ratios and multipolarities of γ radiations, and characteristics of β and α radiations in radioactive decays. The α decays of A=171 nuclei to A=167 daughters are included in this work, while for α decays of A=167 nuclei to A=163 daughters, consult Nuclear Data Sheets (2010Re03) or the ENSDF database for A=163. 167Er, 167Tm, 167Yb, 167Lu and 167Ta are among the most extensively studied nuclides via decay and high-spin gamma-ray spectroscopy measurements, followed by 167Ho, 167Hf, 167W, and 167Os. Information for excited states in 167Dy, 167Re, and 167Ir are limited; no excited states have yet been identified in 167Sm, 167Eu, 167Gd, 167Tb and 167Pt, with the ground-state half-life of 167Sm remaining unknown. This work supersedes the earlier evaluation of A=167 nuclei by 2000Ba65.
Nuclear Data Sheets for A = 151
2009, Nuclear Data SheetsNuclear spectroscopic information for known nuclides of mass number 151 (Cs,Ba,La,Ce,Pr,Nd,Pm,Sm,Eu, Gd,Tb,Dy,Ho,Er,Tm,Yb,Lu) with Z = 55 to 71 and N = 96 to 80 have been evaluated and presented together with adopted energies and Jπ of levels in these nuclei. No excited state data are yet available for 151Cs, 151Ba and 151La; only the isotopic identification has been reported, without information about their half-lives or decay modes. The 151Hf nuclide has not yet been identified. The radioactive decays of 151Ce, 151Ho (35.2-s and 47.2-s activities), 151Er (23.5-s and 0.58-s activities), 151Yb (two activities of about the same half-life) are not well established. For the decay of 151Lu, only the half-life is known.
Superdeformed structures are well established in 151Dy and 151Tb with a total of five SD bands in 151Dy and ten SD bands in 151Tb. In 151Gd, six SD bands have been tentatively assigned. In 151Tb, yrast SD-1 band has now (2008Ro23) been linked to normal-deformed structures through two well-defined high-energy γ transitions and possibly four other tentative γ rays.
This evaluation represents a revision of earlier (1997Si03,1988Si15,1976Ha35) evaluations of A = 151.
Symmetry-unrestricted Skyrme-Hartree-Fock-Bogoliubov calculations for exotic shapes in N=Z nuclei from <sup>64</sup>Ge to <sup>84</sup>Mo
2001, Nuclear Physics ABy performing fully 3D symmetry-unrestricted Skyrme–Hartree–Fock–Bogoliubov calculations, we discuss shape coexistence and possibility of exotic deformations simultaneously breaking the reflection and axial symmetries in proton-rich nuclei: 64Ge, 68Se, 72Kr, 76Sr, 80Zr and 84Mo. Results of calculation indicate that the oblate ground state of 68Se is extremely soft against the triangular deformation, and that the low-lying spherical minimum coexisting with the prolate ground state in 80Zr is extremely soft against the tetrahedral deformation.
Large-scale fission-barrier calculations with the ETFSI method
1998, Nuclear Physics AWithin the context of a project to treat all the nuclear aspects of the astrophysical r-process on a unified microscopic basis, we have extended the ETFSI (extended Thomas-Fermi plus Strutinsky Integral) method to the calculation of fission barriers, and compared our results to a large number of measured barrier heights. With the force SkSC4, on which the ETFSI-1 mass formula was based, we find that if the primary (highest) barrier is lower than 10 MeV, the error never exceeds 1.4 MeV, with either sign being possible. For primary barrier heights lying between 10 and 15 MeV we probably overestimate the height by around 1.5 MeV. It should thus be possible to use the ETFSI method to make reliable calculations of the experimentally inaccessible fission barriers relevant to the r-process.
Deformation of nuclei close to the two-neutron drip line in the Mg region
1997, Nuclear Physics AWe present Hartree-Fock-Bogoliubov (HFB) calculations of the ground states of even Mg isotopes. A Skyrme force is used in the mean-field channel and a density-dependent zero-range force in the pairing channel. 40Mg and 20Mg are predicted to be at the two-neutron and two-proton drip lines respectively. A detailed study of the quadrupole deformation properties of all the isotopes shows that the ground states of 36,38,40Mg are strongly deformed with significantly different deformations for the neutrons and protons. Our study supports the disappearance of the N = 28 shell gap in the Mg and Si isotopes.
Nuclear data sheets for A = 151
1997, Nuclear Data SheetsAbstract:Nuclear spectroscopic information for known nuclides of mass number 151 (Cs, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) with Z=55, 58 to 71 and N=96, 93 to 80 have been evaluated and presented together with adopted energies and Jπ of levels in these nuclei. No excited state data are yet available for151Cs,151Ce, and151Lu. The existence of151Cs is reported from mass separation of products from U(p,X) reaction but there is no information about its half-life.
In151Tb and151Dy, Several excited superdeformed bands have been reported, in addition to the yrast superdeformed band. This evaluation represents a revision of earlier (88Si15) Nuclear Data Sheets for A = 151.
Cutoff Date:Literature available up to January 15, 1997 has been consulted.
General Policies and Organization of Material:See the January issue of Nuclear Data Sheets.
Acknowledgments:The evaluator thanks M. J. Martin at Oak Ridge National Laboratory for a detailed and constructive review of the mass chain, especially, concerning adopted γ-ray branching ratios.
General Comments:The statistical analysis of γ-ray data and deduced level schemes is carried out through computer codes available at Isotopes Project, Berkeley and Nuclear Data Center, Brookhaven. The methodology and procedures for some of these codes are described by 86BrZQ and 86Br21. A general 3% uncertainty is assumed is quoted theoretical internal conversion coefficients taken mainly from 68Ha53. The values of μ and Q are from compilation by 89Ra17, when available.