Abstract
The beta decay of ( h) was studied by beta and gamma spectrometry, with beta counting (supported by other methods) for finding absolute intensities. Gamma transitions (keV), with intensities including internal conversion, are 306.3±0.3 (5.4%), 319.3±0.3 (19.4%), 442.7±0.5 (0.04%), and a (38.77±0.07)-(280.5±0.4) cascade (0.17%). The energy separation between the 306.3- and 319.3- keV gammas is 12.97±0.10 keV. From Pd x-ray intensities, are 5.8±0.6, 0.020±0.004, and 0.012±0.001 for gammas 38.77, 280.5, and (306.3, 319.3) keV, respectively. Several gammas reported by earlier investigators are absent. Population of known levels at 344 and 489 keV does not occur to an observable extent. The beta maximum is 550±54 keV; there is no gamma coincident with it. Betas with maxima 249±17 and 133±15 keV are coincident with the main gamma group (280.5, 306.3, 319.3 keV) and the 442.7-keV gamma, respectively. The Pd x ray is coincident with betas of end point roughly 250 keV. There is no evidence for any levels below 280 keV, and certainly there are no levels below ∼200 keV reached directly by beta transitions. Beta transitions to the indicated 280.5-keV level do not occur (≤0.03%). Inferring spin and parity assignments from these data, we conclude that the decay of (, keV) takes place by beta transitions to levels at 0 (, 75%), 306 (probably , 5.4%), 319 ((, 19.5%), and 443 ( or , 0.04%) keV; and, via a gamma transition from the 319-keV level, to a level at 280 keV (). The results are discussed in terms of the spherical-potential shell model with phonon states, and the spheroidal-potential (Nilsson) model with rotational states. The Nilsson model gives a better account of the findings than might have been expected, although neither model is completely successful.
- Received 18 January 1965
DOI:https://doi.org/10.1103/PhysRev.140.B1516
©1965 American Physical Society