Nuclear Data Sheets最新文献

Evaluated nuclear structure and decay data for all nuclei with mass number A=201 (²⁰¹Os, ²⁰¹Ir, ²⁰¹Pt, ²⁰¹Au, ²⁰¹Hg, ²⁰¹Tl, ²⁰¹Pb, ²⁰¹Bi, ²⁰¹Po, ²⁰¹At, ²⁰¹Rn, ²⁰¹Fr, ²⁰¹Ra) 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 in various decay data sets were determined using the GABS code. This work supersedes the earlier evaluation by F.G. Kondev (2007Ko06), published in Nuclear Data Sheets 108, 365 (2007).

Detailed level schemes, decay schemes, band structure, and the experimental data on which they are based are presented for all nuclei with mass number A=242. The experimental data are evaluated and adopted values are given for level and radiation properties. For references on theory refer to the NSR file at the web site given below under Cutoff Date:. This evaluation replaces the A=242 publication by Y. A. Akovali in Nuclear Data Sheets 96, 177 (2002) (2002Ak06).

Evaluated spectroscopic data and level schemes from radioactive decay and nuclear reaction studies are presented for ²⁴N, ²⁴O, ²⁴F, ²⁴Ne, ²⁴Na, ²⁴Mg, ²⁴Al, and ²⁴Si. This evaluation for A=24 supersedes the earlier one by R. B. Firestone (2007Fi14).

Highlights of this evaluation are the following:

In ²⁴O, the 7.4- and 7.65-MeV groups reported in ¹H(²⁴O,p′) (2012Ts03) and ⁹Be(²⁶F,nX) (2011Ho05), respectively, are considered as separate states in this evaluation, since the former one was observed to decay by only one neutron emission to ²³O, while the latter one by two sequential neutrons to ²²O. Based on assigned configurations, the 7.4- and 7.6-MeV groups are tentatively assigned negative and positive parities, respectively. Additional study would be useful to determine if these states are same or different.

In ²⁴Na, 2014Fi01 (n,γ) proposed J^π=(0,1,2)⁻ for 4048.8 keV level based on weaker population from the capture state (J^π=1⁺,2⁺) and mentioned to reexamine the J^π=0⁺ assignment, suggested in earlier evaluations (1990En08, 2007Fi02).

This evaluation includes the first observation of E0 transition, strength ρ²(E0)=0.380 70, for the 6432 keV transition from 0⁺ state at 6432 to 0⁺ g.s. in ²⁴Mg reported in 2020Do10. Authors proposed the first-excited 0⁺ state of ²⁴Mg to be superdeformed.

In ²⁴Al, the excited level energies deduced from (³He,t) measurements reported by different research groups vary significantly and it was not clear if some of those levels were same or different. Additional measurements are needed.

Experimental nuclear structure and decay data are evaluated for all the 17 known nuclides of mass 149 (Xe, Cs, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb). Detailed compiled and evaluated spectroscopic information is presented for each reaction and decay dataset, and recommended values are provided for level properties, α, β and γ radiations, and other spectroscopic parameters, based on an evaluation of all the available experimental data for A=149 isobaric nuclides. Although large amounts of nuclear spectroscopic data are available for nuclides of A=149, yet large gaps in knowledge exist, as described below. For the lowest atomic number nuclide ¹⁴⁹Xe, only the isotopic identification has been made, with no data for its ground-state half-life. For ¹⁴⁹Cs, ¹⁴⁹Tm and ¹⁴⁹Yb information is available for only the respective ground states. For ¹⁴⁹Ba, ¹⁴⁹La and ¹⁴⁹Er, limited data exist for excited states. Many of the decay schemes of radioactive nuclei of A=149 are considered as incomplete, either due to large energy differences between the highest observed excited states in daughter nuclides and the respective Q-values, or due to the lack of confirmed γ-ray data, as listed below: ¹⁴⁹Cs → ¹⁴⁹Ba, ¹⁴⁹Ba → ¹⁴⁹La, ¹⁴⁹La → ¹⁴⁹Ce, ¹⁴⁹Ce → ¹⁴⁹Pr, ¹⁴⁹Pr → ¹⁴⁹Nd, ¹⁴⁹Tb(4.17 min) → ¹⁴⁹Gd, ¹⁴⁹Ho(21.0 s and 56 s) → ¹⁴⁹Dy, ¹⁴⁹Er(4 s and 9.6 s) → ¹⁴⁹Ho, and ¹⁴⁹Tm → ¹⁴⁹Er. No data exist for the decay of ¹⁴⁹Yb to ¹⁴⁹Tm. Data for half-lives of the excited states in this mass chain are generally lacking as given below by the number of excited levels of known half-life / approximate number of known levels in a nuclide: 2/17 for ¹⁴⁹Ba, 0/18 for ¹⁴⁹La, 3/53 for ¹⁴⁹Ce, 3/44 for ¹⁴⁹Pr, 17/110 for ¹⁴⁹Nd, 9/90 for ¹⁴⁹Pm, 10/210 for ¹⁴⁹Sm, 2/125 for ¹⁴⁹Eu, 6/270 for ¹⁴⁹Gd, 5/200 for ¹⁴⁹Tb, 3/80 for ¹⁴⁹Dy, 3/90 for ¹⁴⁹Ho, and 3/14 for ¹⁴⁹Er. This work supersedes earlier evaluations of A=149 nuclides published by 2004Si16, 1994Si18, 1985Sz01 and 1976Ho17.