Nuclear Data Sheets for A=164

Abstract

Experimental nuclear structure data for the known A=164 isobaric nuclides (Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Os, Ir) have been evaluated, and presented together with Adopted properties of level energies, and associated γ rays. The decay data for these nuclides have also been evaluated, providing Adopted values of γ and β radiations, and log ft values. No excited states are known in 164 Eu, 164 Tb, and 164 Ir. Information for 164 Gd, 164 Re and 164 Os is limited due to insufficient experimental data. For radioactive nuclides, decay schemes of 164 Sm, 164 Gd and 164 Re are not known, and those of 164 W, 164 Tb, 164 Lu, 164 Hf, 164 Ta and 164 W are incomplete. The decay schemes of 164 Ho and the two activities of 164 Tm seem fairly complete. The decay scheme of 164 Yb presents a major problem that the Q(ε) value of 887 keV 29 recommended in 2017Wa10 is in disagreement with the population of levels at 928, 952 and 1060 keV in the daughter nucleus. This decay scheme, which so far has been mainly reported in a secondary reference (1982AdZZ) needs further investigation. Also the masses of 164 Yb and 164 Tm need either new measurements or a re-evaluation to resolve discrepancy of about 220 keV in the Q value of 164 Yb decay to 164 Tm. The reactions and decays for which no new experimental information has become available since the 2001 update have undergone revisions to incorporate conversion coefficients from BrIcc code, and evaluated Q values from 2017Wa10, but the essential content of such datasets may have remained the same as in previous evaluations. Finally, in this respect the present work greatly benefited from all the previous NDS evaluations (2001Si27,1992Sh07, 1986Sh03,1974Bu30), but at the same time data presented herein supersede all the previous published evaluations.