The Auger effect in the heaviest elements has been investigated with magnetic beta-ray spectrometers. $K$-Auger yields for ytterbium, polonium, and uranium of 0.064±0.01, 0.058±0.005, and 0.033±0.010, respectively, were obtained. The $K$-Auger electrons of ytterbium and polonium were resolved into two groups, $K-LL$ and $K-LX$, according as two or one $L$ electrons were involved. The ratios of the intensities of the $K-LX$ electrons to the $K-LL$ electrons for ytterbium and polonium were found to be 0.64±0.05 and 0.55±0.03, respectively. A summary of measurements of $K$-fluorescence yields and $K$-Auger electron intensity ratios is given. A revised decay scheme for ${\mathrm{Np}}^{236}$ and a redetermination of the half-life of ${\mathrm{At}}^{211}$ (7.20±0.05 hours) is included.

• Received 7 November 1955

DOI:https://doi.org/10.1103/PhysRev.101.1306