Auger Effect in Astatine

The $K$-capture decay of ${\mathrm{At}}^{211}$ has been studied using photographic emulsions. The number of Auger electrons per $K$ shell vacated, defined as the Auger coefficient, has been found to be 0.106. This value is somewhat higher than that calculated from theory. ${\mathrm{Bi}}^{207}$, which arises from the alpha-decay of ${\mathrm{At}}^{211}$, was observed to decay by $K$-capture.