The Radiations from Hafnium

The 70-day, 45-day, 5.5-hour, and 19-second activities of Hf have been investigated by spectrometric, spectrographic, absorption, and coincidence methods. From activation experiments on the separated Hf isotopes, the following assignments have been made: 70-day—${}_{72}{}^{}{}_{}{}^{}\mathrm{Hf}_{}^{175}{}_{}{}^{}$; 19-second—${}_{72}{}^{}{}_{}{}^{}\mathrm{Hf}_{}^{179*}{}_{}{}^{}$; 5.5-hour—${}_{72}{}^{}{}_{}{}^{}\mathrm{Hf}_{}^{180*}{}_{}{}^{}$; 45-day—${}_{72}{}^{}{}_{}{}^{}\mathrm{Hf}_{}^{181}{}_{}{}^{}$.