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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

The use of neural networks for approximation of nuclear data

The article discusses the possibility of using neural networks for approximation or reconstruction of data such as the reaction cross sections. The quality of the approximation using fitting criteria is also evaluated. The activity of materials under irradiation is calculated from data obtained using neural networks.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Nuclear Data Sheets for A=189

Evaluated experimental data are presented for 13 known mass 189 nuclides (Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, Po). Since the 2003Wu02 publication, structure and decay data from 25 new and primary publications have been incorporated in the current work, while adding a new 189 Hf nuclide. New data have been added for all nuclides except 189 Au and 189 Hg. Moreover, several previous datasets were modified for β-decay Q values and conversion coefficients even when no new publications appeared since 2003Wu02. In spite of large amounts of data available for A=189 nuclides, several deficiencies remain, which are pointed out below in the hope that further experimental work may improve our knowledge of structure of these nuclides. For 189 Hf and 189 Ta, ground-state half-lives, and their decay schemes are unknown. An isomer in 189 Ta has recently been established but its decay characteristics are unknown, even though several gamma rays were connected with its decay. No excited states are known in 189 W and only one in 189 Po. The decay scheme of 189 W is known poorly with most gamma rays left as unassigned. The decay schemes of 189 Au and 189 Pb g.s. suffer from incompleteness, while those for the g.s. and isomer of 189 Tl are almost absent. The decay schemes of g.s. and isomer of 189 Hg are very complex as apparent from the study by 1996Wo04. Evaluators feel that these two decay schemes could be improved with modern gamma-ray detector arrays. While several isomers are known in many of the A=189 nuclides, there is in general lack of information of level half-lives, thus limiting the knowledge of transition probabilities. High-spin structures, including SD bands in 189 Hg and 189 Tl, are known in 189 Re, 189 Ir, 189 Pt, 189 Au, 189 Hg, 189 Tl, 189 Pb and 189 Bi. Single-particle transfer data are available for 189 Re, 189 Os, and 189 Pt; and two-neutron transfer data for 189 Ir.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2018

Recommended nuclear data for medical radioisotope production: diagnostic gamma emitters

An extensive series of evaluations have been performed as part of an IAEA coordinated research project to study a set of nuclear reactions that produce the diagnostic gamma-ray emitting radionuclides Cr- 51 , Tc- 99m , In- 111 , I-123 and Tl- 201 . Recommended cross-section data in the form of excitation functions have been derived, along with quantifications of their uncertainties. These evaluations compiled the compilation of all previously published values and newly measured experimental data, followed by critical assessments and selection of those experimental datasets and accompanying uncertainties judged to be fully valid and statistically consistent for model-independent least-squares fitting by means of Pade approximations. Integral yields as a function of the energy were also calculated on the basis of the recommended cross sections deduced from these various fits. All evaluated numerical conclusions and their corresponding uncertainties are available online at www-nds.iaea.org/medical/gamma_emitters.html and also on the medical portal of the International Atomic Energy Agency/Nuclear Data Section (IAEA-NDS) www-nds.iaea.org/medportal

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

Nuclear Data Sheets for A=252

The experimental results from the various reaction and radioactive decay studies leading to nuclides in the A=252 mass chain have been reviewed. Nuclides ranging from U (Z=92) to Lr (Z=103) are included. For these nuclei, level and decay schemes, as well as tables of nuclear properties, are given. This work supersedes the previous evaluation of the data on these nuclides (2005Ni22).

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗