Nuclear Data Sheets最新文献

Evaluated spectroscopic data and level schemes from radioactive decay and nuclear reaction studies are presented for ¹⁹¹Hf, ¹⁹¹Ta, ¹⁹¹W, ¹⁹¹Re, ¹⁹¹Os, ¹⁹¹Ir, ¹⁹¹Pt, ¹⁹¹Au, ¹⁹¹Hg, ¹⁹¹Tl, ¹⁹¹Pb, ¹⁹¹Bi, ¹⁹¹Po, and ¹⁹¹At. This evaluation for A=191 supersedes the earlier one by V.R. Vanin et. al. (2007Va21), published in Nuclear Data Sheets 108, 2393 (2007).

The experimental nuclear spectroscopic data for known nuclides of mass number 76 (Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Kr, Rb, Sr, Y) have been evaluated and presented together with Adopted properties for levels and γ rays. With the exception of structure data for ⁷⁶Ga nucleus, significant new data have been incorporated for all the other nuclides of A=76 since the previous 1995 update in ENSDF database and NDS publication 1995Si03. No data are yet available for excited states in ⁷⁶Fe, ⁷⁶Cu and ⁷⁶Y. Decay scheme characteristics for the decay of ⁷⁶Co, ⁷⁶Ni, and ⁷⁶Y are unknown while those for decays of ⁷⁶Cu and ⁷⁶Sr seem incomplete. For ⁷⁶Ni, very little structure data are available, and for ⁷⁶Ga and ⁷⁶As, only low-spin ($\text{J}<4$ or so) information is available. This work supersedes the data presented in the previous (1995Si03) NDS evaluation of A=76.

Experimental nuclear spectroscopic data are compiled and evaluated for 18 known nuclides of mass 165 (Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Os, Ir, Pt). Detailed information is presented for each reaction and decay experiment. Combining all the available data, recommended values are provided for energies, spins and parities, and half-lives of levels, with energies, branching ratios and multipolarities of γ radiations, and characteristics of β and α radiations in radioactive decays. ¹⁶⁵Dy, ¹⁶⁵Ho, ¹⁶⁵Er, ¹⁶⁵Tm, ¹⁶⁵Yb, ¹⁶⁵Lu and ¹⁶⁵Hf are among the most extensively studied nuclides via decay and high-spin gamma-ray spectroscopy measurements, followed by limited data for ¹⁶⁵Tb, ¹⁶⁵Ta, ¹⁶⁵W, ¹⁶⁵Re, and ¹⁶⁵Os. No excited states have yet been identified in ¹⁶⁵Sm, ¹⁶⁵Gd, and ¹⁶⁵Pt, while for ¹⁶⁵Eu and ¹⁶⁵Ir, information is available for only the g.s. and an isomer, but with no γ rays. This work supersedes earlier evaluation of A=165 nuclides by 2006Ja09.

Precise integral measurement of fast neutron-induced fission product yields for various actinides is of high interest for applied nuclear science. The goal of this effort is to improve uncertainties in fission product yield values of ²³⁷Np. Fission was induced in a NpO₂(NO₃) target using the Godiva IV critical assembly in burst mode. The irradiated sample was transferred to a high-resolution γ-ray detection setup within 50 minutes. γ-ray list mode data was collected from 50 minutes to 1 week after the irradiation. γ-ray spectroscopy was performed to analyze the time dependent γ-ray yields using an automated peak search algorithm to identify isotopes by their decay γ-ray energy and half-life. The initial activity for each isotope identified was used to calculate their fission product yield.

The half-life of ²²Na has been determined through 523 activity measurements over 14.5 years with a re-entrant ionisation chamber in a temperature-stabilised room. The data were selected and aggregated from in total 127 830 ionisation current measurements with a reproducibility of the order of 0.065 % standard deviation. The ionisation current was collected over an air capacitor and measured as a change of voltage over time, which warrants excellent linearity with activity throughout the experiment. The residuals to an exponential decay curve show a distinct annual cycle of 0.0055 (5) % amplitude, which reduces to 0.0012 (5) % after compensation for a correlation with ambient humidity. The data confirm the validity of the exponential-decay law, in absence of cyclic perturbations at daily, monthly, and multi-annual scale at the level of 0.0005 % standard deviation. The ²²Na half-life value obtained in this study is 950.68 (12) d or 2.60290 (34) a, with a relative standard uncertainty of 0.013 %. This value is consistent with the mean value of other measurement results in the literature, although the latter have an issue with incomplete uncertainty budgets. Owing to the high statistical accuracy and conservative uncertainty estimate of systematic errors, the result obtained in this work can be recommended as a reliable reference value.

Precise integral measurement of fast neutron-induced fission product yields for various actinides is of high interest for applied nuclear science. The goal of this effort is to improve uncertainties in fission product yield values of ²³⁹Pu. Fission was induced in a pure ²³⁹Pu ($>99\text{\%}$) target using the Godiva IV critical assembly in burst mode. The irradiated sample was transferred to a high-resolution γ-ray detector within 45 minutes. γ-ray list mode data was collected from 45 minutes to 1 week after the irradiation. γ-ray spectroscopy was performed to analyze the time dependent γ-ray yields using an automated peak search algorithm to identify isotopes by their decay γ-ray energy and half-life. The initial activity for each isotope identified was used to calculate their fission product yield.