Decay of 167Yb

Abstract

The decay of 167Yb has been investigated by means of β- and γ-scintillation spectrometry. A positon emission of 0.2% with the end point energy of 700±70 keV was found to accompany the main electron capture transition from the ground state ( 5 2 −(523) of 167Yb to the 292.7 keV level ( 7 2 −(523)) of 167Tm. The log ft value for this transition was determined to be 4.63±0.03, which is consistent with an allowed and unhindered characteristic of this transition. A new γ-ray of 1050 keV was observed, and a corresponding intrinsic state 5 2 +(413) was proposed at the 1230 keV excited state of 167Tm from the cascade relation of the γ-rays. Half lives of the 179.4 keV and 292.7 keV levels were determined to be 1.1±0.1 μsec and 0.9±0.1 μsec, respectively, from fast γ-γ coincidence and delayed γ-γ coincidence experiments. An E2 transition from the 179.4 keV level ( 7 2 +(404) ) to the 10.4 keV level ( 3 2 , 1 2 +(411)) was established from γ-γ coincidence measurements. On the basis of the unified model, a decay scheme is discussed to incorporate the present experimental results.