Nuclear Data Sheets for A=81

Nuclear structure data pertaining to all nuclei with mass number A=81 (Ni, Cu, Zn, Ga, Ge, As, Se, Br, Kr, Rb, Sr, Y, Zr, Nb, Mo) have been compiled and evaluated and incorporated into the ENSDF data file. This evaluation for A=81 supersedes the previous one, 2008Ba34. Highlights of this evaluation are the following: From fragmentation reaction studies of 238 U beam at 345 MeV/nucleon on a Be target, one count has been assigned to 81 Ni in 2017Su15, which is assumed to correspond to the g.s. activity of 81 Ni and the Adopted Levels dataset has been proposed. The absolute I γ determined in 1982De36 ( 81 Y ε decay (70.4 s)) from total I γ /total β + recoils implies a 97% g.s. branch (from (5/2 + ) to 1/2 − ) in the 81 Y ε decay, which is discrepant compared to the g.s. feeding of <2.6 in this evaluation. The absolute I γ of 1982De36 was not considered in the previous evaluation (2008Ba34), same in this one as well. The reason for this major discrepancy is not understood. The decay scheme normalization is consequently tentative. 81 Zr g.s. half-life measurements have been reported from (113, 175, and 230 γ (t)) and decay curves for β events correlated with 81 Zr implantations. No additional data are available. A 81 Zr ε decay (5.3 s) dataset has been created based on the data from the Adopted Levels, Gammas of 81 Y.