Nuclear Data Sheets最新文献

The ²³⁹Pu(n,f)/²³⁵U(n,f) cross-section ratio has been measured with the fission Time Projection Chamber (fissionTPC) from 100 keV to 100 MeV. The fissionTPC provides three-dimensional reconstruction of fission-fragment ionization profiles, allowing for a precise quantification of measurement uncertainties. The measurement was performed at the Los Alamos Neutron Science Center which provides a pulsed white source of neutrons. The data are recommended to be used as a cross-section ratio shape. A discussion of the status of the absolute normalization and comparisons to ENDF evaluations and previous measurements is included.

The evaluated experimental data are presented and evaluated for 13 known nuclides of mass 64 (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se). For each nuclide, the best values combining all available data are recommended for spectroscopic properties. No excited states have been identified in ⁶⁴Ti, ⁶⁴As, and ⁶⁴Se. Only one excited state in ⁶⁴V as an isomer, and three in ⁶⁴Cr have been identified. Data for excited states in ⁶⁴Mn, ⁶⁴Fe, and ⁶⁴Co remain limited. ⁶⁴Ni, ⁶⁴Cu, and ⁶⁴Zn are the most studied nuclides through various reactions and decays, followed by ⁶⁴Ga and ⁶⁴Ge. In the opinion of the evaluators, there are several incomplete or discrepant aspects of the high-spin portion of the level scheme for ⁶⁴Zn above ≈5 MeV excitation which need to be resolved in further experiments using large γ-detector arrays. The decay schemes of ⁶⁴Ti β⁻, ⁶⁴As ε and ⁶⁴Se ε are unknown, while very little information is available for ⁶⁴V β⁻ and ⁶⁴Cr β⁻. The decay schemes of ⁶⁴Mn β⁻, ⁶⁴Fe β⁻, ⁶⁴Co β⁻ and ⁶⁴Ge ε are somewhat better known, but still considered incomplete by evaluators. The decay scheme of ⁶⁴Ga ε decay is known in detail, however there is the possibility of additional levels populated above 4713 keV, as the Q(ε) value is 7171 keV. The β⁻, β⁺ and ε decay modes of ⁶⁴Cu are well known, as this radionuclide is of great importance in applications, for example, as a dosimeter for neutron flux determination in nuclear reactors, and as a radiopharmaceutical for positron emission tomography (PET). This work supersedes earlier full evaluations of A=64 by 2007Si04, 1996Si12, 1991Si03, 1979Ha35 and 1974Au04.

Evaluated nuclear structure and decay data for all nuclei with mass number A=203 (²⁰³Os, ²⁰³Ir, ²⁰³Pt, ²⁰³Au, ²⁰³Hg, ²⁰³Tl, ²⁰³Pb, ²⁰³Bi, ²⁰³Po, ²⁰³At, ²⁰³Rn, ²⁰³Fr, ²⁰³Ra) are presented. All available experimental data are compiled and evaluated, and best values for level and γ-ray energies, quantum numbers, lifetimes, γ-ray intensities and transition probabilities, as well as other nuclear properties, are recommended. Inconsistencies and discrepancies that exist in the literature are discussed. A number of computer codes (https://www-nds.iaea.org/public/ensdf_pgm/index.htm) developed by members of the NSDD network were used during the evaluation process. For example, the reported absolute γ-ray emission probabilities and their uncertainties were determined using the GABS code. The γ-ray transition probabilities were determined using the RULER code and the corresponding uncertainties were estimated by means of a Monte-Carlo approach. This work supersedes the earlier evaluation by F.G. Kondev (2005Ko20), published in Nuclear Data Sheets 105, 1 (2005).

Experimental nuclear structure and decay data are evaluated for all of 14 known nuclides of mass 194 (Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, Po, At, Rn). Detailed evaluated spectroscopic information is presented for each reaction and decay experiment, and by combining all the available data, recommended values are provided for energies, spins and parities and half-lives of levels, together with energies, branching ratios and multipolarities of gamma radiations from the levels, and characteristics of beta and alpha radiations in radioactive decays. No excited states have yet been identified in ¹⁹⁴Ta, ¹⁹⁴W, and ¹⁹⁴Rn. Only limited spectroscopic data are available for ¹⁹⁴Re, with a 45−μs isomer identified, but its absolute energy yet to be determined. Only two levels at unknown absolute energies are reported for ¹⁹⁴At, both of which are isomeric but neither can be unambiguously identified as the ground state. Data are scarce for ¹⁹⁴Os, ¹⁹⁴Bi and ¹⁹⁴Po, while ¹⁹⁴Pt, ¹⁹⁴Au, ¹⁹⁴Hg, ¹⁹⁴Tl and ¹⁹⁴Pb are well studied through decays and reactions. For ¹⁹⁴Ir, although a major (n, γ), E=thermal study and two particle-transfer studies provide large amounts of spectral data, still several problematic issues are found in the assignment of multipolarities for the secondary gamma transitions in the (n, γ) study by 2008Ba25, 1998Ba85 and 1998Ba42, all from the same group. Some issues have been resolved by the evaluators, but we suggest that further experimental work is needed on ¹⁹⁴Ir structure to resolve standing issues, and verify the conclusions made by 2008Ba25. Our attempt to contact the prime authors of the 2008Ba25 paper was not successful. The present work supersedes all the earlier evaluations of A=194 nuclides by 2006Si17, 1996Br26, 1989Si01 and 1972Au11.

The experimental results published before May 2021 from the various reaction and decay studies leading to nuclides of Z=59 to Z=75, ¹⁶⁰Pr, ¹⁶⁰Nd, ¹⁶⁰Pm, ¹⁶⁰Sm, ¹⁶⁰Eu, ¹⁶⁰Gd, ¹⁶⁰Tb, ¹⁶⁰Dy, ¹⁶⁰Ho, ¹⁶⁰Er, ¹⁶⁰Tm, ¹⁶⁰Yb, ¹⁶⁰Lu, ¹⁶⁰Hf, ¹⁶⁰Ta, ¹⁶⁰W, ¹⁶⁰Re in the A=160 mass chain have been reviewed. These data are summarized and presented, together with adopted level schemes and properties. This work is intended to supersede the previous evaluation of the A=160 nuclides by C.W.Reich (2005Re18), which was published in Nuclear Data Sheets 105, 557 (2005).