Abstract
To obtain more data on the system of levels in even-even nuclei, a number of such nuclei () were studied with electron-capturing sources in permanent magnet spectrogaphs. Some measurements were made with scintillation counters. Data confirming recently reported results on the decay of , , and have been obtained. It was found that has two isomeric states ( hr and > 5 yr). Levels at 740.7 (0+) and 773.3 (4+) kev in are proposed. A study of the two isomeric activities of indicated the existence of levels in which may be described as a gamma-vibrational band (at 997.3 kev) and a beta-vibrational band (at 680.6 kev). The new data for (7.7 hr) are consistent with levels in at 2137.3 and 2164.6 kev, both of which are probably 3 states and which exhibit considerably different branching ratios of the de-exciting transitions. The decay of appears to populate a large number of even-parity levels in which may be arranged in rotational bands corresponding to primary or base states at 1174.0 kev (), 1467.5 kev (), 1664.3 kev (), 1702.1 kev (), 2075.0 kev (), and 2287.3 kev (). The very complex decay of the two isomers of excite many odd-parity levels which may be arranged in seven or more bands. In addition, even-parity beta- and gamma-vibrational bands may be populated. Electron-capture decay of populates a gamma-vibrational band in of spins 2, 3, and 4. Data relevant to the rotational energy parameters and ratios of gamma-ray transition probabilities from the various states are presented. As a corollary, data on the decay of are presented since this activity was present in some of our composite sources.
- Received 17 April 1961
DOI:https://doi.org/10.1103/PhysRev.123.1758
©1961 American Physical Society