Nuclear Data Sheets for A=194

Abstract

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.