Evaluation of fission barrier parameters from near-barrier fission and isomeric half-life data
Abstract
A combined analysis of data from narrow intermediate structure in near-barrier fission cross sections and from shape-isomer half-lives has been tried in a very phenomenological model. Among the results, one observes a marked even-odd effect in the ħω values, whilst the barrier heights do not show a significant effect of this type. It seems that one of the most important open questions is whether or not narrow intermediate structure exists close to the neutron binding energy in the Cm isotopes.
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Nuclear Data Sheets for A=245
2023, Nuclear Data SheetsAvailable information pertaining to the nuclear structure of ground and excited states for all known nuclei with mass numbers A=245 have been compiled and evaluated. The adopted level and decay schemes, as well as the detailed nuclear properties and configuration assignments based on experimental data, are presented for these nuclides. When there are insufficient data, expected values from systematics of nuclear properties and/or theoretical calculations are utilized. Unexpected or discrepant experimental results are also noted. Since the last evaluation, new rotational bands in 245Pu have been observed to high spin from transfer reaction 244Pu(209Bi, 208Biγ) by 2014Ho16. While in 245Am, the 249Bk α decay measurements by 2013Ah03 added a new rotational band based on π3/2[521] configuration. The 245Pu β− decay scheme is basically what was proposed in the late 60's and 47 γ rays have still not been placed. In 245Cm, precise alpha energies and intensities were measured by 2015Ah03 in 249Cf α decay. Their reported alpha energies of the main α group were about 2 keV lower than in the previous evaluation. The spin and parity of the g.s. of 245Es is still ambiguous as more detailed information on the decay is needed. With the production of 249No via fusion evaporation reaction by groups in Dubna and GSI, it's alpha decay was studied and some properties of the daughter 245Fm were published and included in this evalaution. Information on the other nuclides is scarce and not much has been investigated since the last evaluation. A summary and compilation of the discovery of the various nuclides in this mass region is given in: 2013Fr02 (245Pu, 245Am, 245Cm, 245Bk, 245Cf), 2011Me01 (245Es), and 2013Th02 (245Md, 245Fm).
Nuclear Data Sheets for A=242
2022, Nuclear Data SheetsDetailed level schemes, decay schemes, band structure, and the experimental data on which they are based are presented for all nuclei with mass number A=242. The experimental data are evaluated and adopted values are given for level and radiation properties. For references on theory refer to the NSR file at the web site given below under Cutoff Date:. This evaluation replaces the A=242 publication by Y. A. Akovali in Nuclear Data Sheets 96, 177 (2002) (2002Ak06).
Nuclear Data Sheets for A=244
2017, Nuclear Data SheetsAvailable information pertaining to the nuclear structure of ground and excited states for all known nuclei with mass numbers A=244 have been compiled and evaluated. The adopted level and decay schemes, as well as the detailed nuclear properties and configuration assignments based on experimental data are presented for these nuclides. When there are insufficient data, expected values from systematics of nuclear properties and/or theoretical calculations are quoted. Unexpected or discrepant experimental results are also noted. Information provided in 244U is tentative as it is from the possible production in the study of 1960Di03 of debris of the first large-scale thermonuclear test (Ivy Mike) of November 1, 1952 in the Pacific Ocean. No new experimental data are available for 244Np with the information for g.s Jπ considered tentative. Experimental work is needed for 244Np as theoretical work and systematics along with the Gallagher-Moszkowski rules that suggest either Jπ=2+ or . Jπ = () g.s has been considered by the evaluator due to population of high spin states in the beta decay study. In 244Pu, a new K isomer was identified and in addition rotational bands built on the isomer have been observed via the deep inelastic excitation. However, there has been no new measurements since the last evaluation to determine the ratio of the energy levels of the first 4+ state to the first 2+ state (E4+/E2+) in 244Pu that showed a discrepancy from a typical value of 3.333. In the current evaluation, the evaluator has considered the 110γ measured in the 244Np β-decay questionable. Further research into the determination of the gammas depopulating these levels is necessary. In 244Am, specifically the (d,p) transfer reaction and in the (n, γ) secondary γ's, there are a large number of gammas that are unplaced. Since its last measurement in 1966, the electron capture dataset has been updated with a tentative partial level scheme for 244Cm which also provided a new half-life measurement for 244Bk. In 244Fm, a fusion evaporation experiment measured the half-life and provided upper limits for the SF, α decay, and ε branching. A summary and compilation of the discovery of various isotopes in this mass region is given in 2013Fr02 (244Np, 244Pu, 244Am, 244Cm, 244Bk, and 244Cf), 2011Me01 (244Es), and 2013Th02 (244Fm). This work supersedes the 2003 evaluation by Y.A. Akovali (2003Ak04).
Nuclear Data Sheets for A = 238
2015, Nuclear Data SheetsNuclear Data Sheets for A = 241
2015, Nuclear Data SheetsAvailable information pertaining to the nuclear structure of ground and excited states for all known nuclei with mass numbers have been compiled and evaluated. The adopted level and decay schemes, as well as the detailed nuclear properties and configuration assignments based on experimental data are presented for these nuclides. When there are insufficient data, expected values from systematics of nuclear properties or/and theoretical calculations are quoted. Unexpected or discrepant experimental results are also noted. A summary and compilation of the discovery of various isotopes in this mass region is given in 2013Fr02 (241Np, 241Pu, 241Am, 241Cm, 241Bk, and 241Cf), 2011Me01 (241Es), and 2013Th02 (241Fm).
Nuclear Data Sheets for A = 243
2014, Nuclear Data SheetsAvailable information pertaining to the nuclear structure of all nuclei with mass numbers A=243 is presented. Various decay and reaction data are evaluated and compared. Adopted data, levels, spin, parity and configuration assignments are given. When there are insufficient data, expected values from systematics of nuclear properties or/and theoretical calculations are quoted. Unexpected or discrepant experimental results are also noted. A summary and compilation of the discovery of various isotopes in this mass region is given in 2013Fr02 (243Np, 243Pu, 243Am, 243Cm, 243Bk, and 243Cf), 2011Me01 (243Es), and 2013Th02 (243Fm).