Nuclear Data Sheets for A=81

Abstract

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 ²³⁸U beam at 345 MeV/nucleon on a Be target, one count has been assigned to ⁸¹Ni in 2017Su15, which is assumed to correspond to the g.s. activity of ⁸¹Ni and the Adopted Levels dataset has been proposed.

The absolute Iγ determined in 1982De36 (⁸¹Y ε decay (70.4 s)) from total Iγ/total β⁺ recoils implies a 97% g.s. branch (from (5/2⁺) to 1/2⁻) in the ⁸¹Y ε decay, which is discrepant compared to the g.s. feeding of <2.6 in this evaluation. The absolute Iγ 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.

⁸¹Zr g.s. half-life measurements have been reported from (113, 175, and 230γ(t)) and decay curves for β events correlated with ⁸¹Zr implantations. No additional data are available. A ⁸¹Zr ε decay (5.3 s) dataset has been created based on the data from the Adopted Levels, Gammas of ⁸¹Y.