Nuclear Data Sheets for A=189

Abstract

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.