Radiations fromHf181

Abstract

The radiations from ${\mathrm{Hf}}^{181}$ have been examined with a magnetic lens spectrometer. Four gamma-rays were found having energies of 0.087, 0.134, 0.347, and 0.485 Mev. There is evidence for the existence of a fifth gamma-ray. The maximum energy of the beta-rays was estimated to be 0.41 Mev. The three higher energy gamma-rays were found to have intensities proportional to 11, 29, and 100, respectively. The total internal conversion coefficient for the 0.134-Mev transition was calculated to be 11. Calculations on the lifetime and the ratio of the conversion electrons in the $K$ and $L$ shells indicate that in the transition from the metastable state the nucleus undergoes a spin change of three units.