The authors combine modern theoretical calculations with evaluated selected experimental data to produce a comprehensive data resource of K- and L-x-ray transition and absorption edge energies for all of the elements from neon to fermium. The theoretical and experimental components of this work are the result of programs of parallel development extending over more than 20 years. At each of several progressively more refined comparisons, it was possible to identify theoretical components whose systematic improvement then led to the next level of refinement in comparisons with an increasingly robust experimental reference data set. We have now reached a certain practical limit in what can be undertaken with reasonable levels of theoretical effort. This limit is not very different from the practical level of accuracy that can be meaningfully associated with the experimental data. For the more prominent diagram lines, experiment and theory are concordant with a zero-centered distribution of residuals whose statistical metrics allow the uncertainties to be estimated. For the light elements $(Zl20)$ and the very heavy elements $(Zg90)$ there are significant difficulties, as is also the case for a few isolated elements and transitions for $20lZl90.$ Overall, the results reported here represent improvements over previously available data compilations not only because of their scope but also because of their attempt to offer internal metrics of the database accuracy. The identified regions of difficulty are areas where further experimental work may be directed to see if there may remain theoretical issues that are still unresolved.

X-ray transition energies: new approach to a comprehensive evaluation

This document is the latest in a series of compilations of fission yield data Fission yield measurements reported in the open literature and calculated charge distributions have been used to produce a recommended set of yields for the fission products The original data with reference sources, and the recommended yields axe presented in tabular form These include many nuclides which fission by neutrons at several energies These energies include thermal energies (T), fission spectrum energies (F), 14 meV High Energy (H or HE), and spontaneous fission (S), in six sets of ten each Set A includes U235T, U235F, U235HE, U238F, U238HE, Pu239T, Pu239F, Pu241T, U233T, Th232F Set B includes U233F, U233HE, U236F, Pu239H, Pu240F, Pu241F, Pu242F, Th232H, Np237F, Cf252S Set C includes U234F, U237F, Pu240H, U234HE, U236HE, Pu238F, Am241F, Am243F, Np238F, Cm242F Set D includes Th227T, Th229T, Pa231F, Am241T, Am241H, Am242MT, Cm245T, Cf249T, Cf251T, Es254T Set E includes Cf250S, Cm244S, Cm248S, Es253S, Fm254S, Fm255T, Fm256S, Np237H, U232T, U238S Set F includes Cm243T, Cm246S, Cm243F, Cm244F, Cm246F, Cm248F, Pu242H, Np237T, Pu240T, and Pu242T to complete fission product yield evaluations for 60 fissioning systems in all This report also serves as the primary documentation for the second evaluation of yields in ENDF/B-VImore » released in 1993« less

/pdf/evaluation-and-compilation-of-fission-product-yields-1993-ytlx59c9lt.pdf

Evaluation and compilation of fission product yields 1993

Nuclear-charge distribution and delayed-neutron yields for thermal-neutron-induced fission of 235U, 233U, and 239Pu and for spontaneous fission of 252Cf

Relativistic radioactive beams: A new access to nuclear-fission studies

Unambiguous evidence for fission-produced nuclides in meteorites has been shown in the abundance pattern of the Xe isotopes from the Pasamonte meteorite. Calculation of the age of the meteorite from fissiogenic Xe136 and uranium contents of the meteorite yields a value of T′ = 2 × 1010 years, which seems far too large. The result of this calculation leads to the conclusion that part of the fissiogenic Xe in Pasamonte must have been produced by other fissionable nuclide(s), such as Pu244, in addition to U238. Assuming that the fissiogenic Xe136 in Pasamonte is produced from spontaneous fission of U238 and extinct Pu244, then Ξ, the time interval between the cessation of nucleosynthesis and formation of the meteorite, is estimated to be ∼300 m.y.

Fissiogenic xenon from the pasamonte meteorite

The distribution of mass in the spontaneous fission of $^{256}\mathrm{Fm}$ has been investigated by the radiochemical determination of the fission yields for 28 mass chains. The mass distribution is asymmetric with a peak-to-valley ratio of \ensuremath{\sim}12. The average masses of the light and heavy groups are 111.9 and 141.0, respectively. The fission-yield data indicate a value of 3 \ifmmode\pm\else\textpm\fi{} 1 for $\overline{\ensuremath{\nu}}$, the average number of neutrons emitted per fission. A comparison of the characteristics of the mass distribution for low-energy fission of nuclides ranging from $^{227}\mathrm{Th}$ to $^{256}\mathrm{Fm}$ is given.

Distribution of Mass in the Spontaneous Fission of Fm 256

Nuclear properties of 242Cf, 243Cf, 244Cf and 245Cf

Nuclear decay properties of light einsteinium isotopes

The mass distribution for spontaneous fission of /sup 254/Fm was determined for both pre- and post-neutron-emission fragments. The post-neutron-emission (final) mass distribution was deduced from radiochemical measurements of 24 mass yields. Starting with an assumed distribution of neutron yield versus fragment mass, the pre-neutron-emission (initial) mass distribution and neutron-yield distribution were derived from the kinetic-energy measurements of the fragments and the final-mass distribution by an iterative method. These distributions together with distributions of fragment kinetic energy, total kinetic energy of both fragments, and average kinetic energy and average total kinetic energy as functions of fragment mass are presented. The results are discussed in terms of a scission-point model of fission.

R.K. Sjoblom

Papers

Distribution of Mass in the Spontaneous Fission of Fm 256

Nuclear properties of 242Cf, 243Cf, 244Cf and 245Cf

Nuclear decay properties of light einsteinium isotopes

Distribution of mass, kinetic energy, and neutron yield in the spontaneous fission of /sup 254/Fm

Pulse radiolysis studies of americum(III) and curium(III) ions in perchlorate media. The preparation of Am II, Am IV, Cm II and Cm IV