Technical noteIndications of the validity of the liquid drop model for spontaneous fission half-lives
Abstract
The liquid drop model predicts a linear dependence between the logarithm of spontaneous fission half-lives and the parameter Z2/A. This linear dependence is obtained when assuming that barrier curvature is constant. We have found this linear dependence only in long-lived even-even isotopes with Z2/A less than 38.5, with the same 2Z-N values.
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Nuclear Data Sheets for A=236
2022, Nuclear Data SheetsExperimental nuclear structure and decay data are evaluated for all of 10 known nuclides of mass 236 (Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf). For each nuclide, detailed evaluated spectroscopic information is presented in each reaction and decay, and the best values combining all available data are recommended for level properties, γ and β radiations, and other spectroscopic properties in the Adopted Levels and Gammas. The present evaluation supersedes the earlier one on A=236 by E. Browne, J. K. Tuli (2006Br20), published in Nuclear Data Sheets 107, 2641 (2006).
The atomic nucleus, nuclear radiation, and the interaction of radiation with matter
2020, Handbook of Radioactivity Analysis: Volume 1: Radiation Physics and DetectorsThe chapter includes a history of the discovery and characterization of radioactivity. It follows with a description of the properties of atomic constituents, and the relation between mass and energy. This is followed with a treatment on the properties of the nucleus, nuclear forces, binding energy, nuclear models, and the relativistic properties of nuclear radiation. Natural and artificially produced radionuclides are discussed including radionuclides of cosmogenic origin and natural radionuclide decay chains. Nuclear reactions are discussed including reaction types, energy of reactions (Q value), and reaction cross section. A treatment of alpha decay, beta decay including negatron emission, positron emission, electron capture (EC), double beta (ββ) decay, and the interactions of alpha and beta radiation with matter. Also discussed are internal conversion and Auger electron emissions and a detailed treatment of neutron sources, interaction of neutrons with matter, neutron attenuation and cross section, and neutron decay. The wave-particle dual nature of matter is discussed and a treatment of electromagnetic radiation or photons including the mechanisms of photon interaction with matter. Cherenkov radiation, its origin, and properties are discussed. The origins, properties and applications of synchrotron radiation are also discussed. The chapter continues with a treatment of nuclear recoil and the calculations of recoil energy following alpha, beta, gamma, X-ray, and neutrino emission in radionuclide decay. Cosmic radiation is discussed including the origins, properties, classification, and showers of the cosmic radiation. A treatment of radiation dose, stopping power, and linear energy transfer is included. The principles of radionuclide decay, ingrowth, and equilibrium are included. There is also a discussion of radioactivity units and the correlation of radioactivity and radionuclide mass.
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 = 239
2014, Nuclear Data SheetsSpectroscopic data and level schemes from radioactive decay and nuclear reaction studies are presented here for all nuclei with mass number A=239.
In general, a relatively small amount of new data on this mass chain has been reported since the previous evaluation in 2003. However, special evaluations, such as “Database of prompt gamma rays from slow neutron–capture from elemental analysis” (2007ChZX), have provided additional precise data for levels in 239U. Also, new Coulomb excitation measurements in 239Pu have extended the knowledge of the 1/2[631] rotational band up to , and that of the octupole vibrational band up to .
For historical knowledge it is worth mentioning the report on the “Discovery of isotopes of the transuranium elements with 93 <= Z <= 98” (2013Fr02), where the information for elements Np, Pu, Am, and Cf with mass number A=239 is presented.
The alpha hindrance factors (HF) presented in this evaluation were calculated using values of the radius parameter (r0) interpolated from those for even–even adjacent nuclei given by 1998Ak04.
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).