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Published March 1, 1961 | public
Journal Article Open

Decay of Hf180m


The energies and relative intensities of the gamma radiation and the relative intensities of the conversion electrons following the decay of 5.5-hr Hf180m have been measured using the curved-crystal gamma-ray spectrometer (recently calibrated for accurate intensity measurements), the ring-focused beta-ray spectrometer, and the semicircular spectrometer at the California Institute of Technology. The measured transition energies are: 57.54±0.01, 93.33±0.02, 215.25±0.13, 332.5±0.3, and 443.8±0.6 kev. The energy levels deduced from these values are not entirely consistent with the two-parameter rotational formula. Conversion coefficients derived from the measurements were absolutely normalized using a method involving information available from the decay scheme. All of the 57.54-kev transition conversion coefficients are anomalously high if compared with the theoretical E1 coefficients. No admixture of M2+E3 can account for the anomaly. The K conversion coefficients of the E2 transitions are all about 10% low with exception of the 93.33-kev transition. The L coefficients have a varying deviation, the maximum being 12%. The K conversion coefficient of the 501.3-kev transition has the value 0.037±0.012 which is consistent with the theoretical E3 value of 0.040.

Additional Information

©1961 The American Physical Society. Received 26 October 1960. We wish to acknowledge the assistance of E. Seppi, A. Lebor, and R. Cohen in the collection of data, and of Dr. E. R. Cohen for outlining the least-squares procedure to be used where the input data is highly correlated. Thanks are also due to Dr. J. W. M. DuMond and Dr. G. Nijgh for helpful discussions and criticism.


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