THE NUCLEAR ENERGY LEVELS AND METASTABLE STATES IN THE DECAY OF Yb$sup 16$$sup 9$
The transitions in the electron capture decay of Yb/sup 169/ to Tm/sup 169/ were studied by means of an intermediateimage beta spectrometer to detect internal conversion electrons, and a scintillation detector to study gamma rays. Transition energies of 8.4, 20.8, 63.1, 93.6, 307.7 kev were measured. Measurements of gammagamma as well as beta-gamma coincidences were conducted which included both prompt and delayed coincidence Mns. These data established the existence of nuclear energy levels at 8.4, 118.2, 139.0, 316.2, 379.3, and 472.9 kev above the ground state of Tm/sup 169/. The 316.2 and 379.3 kev levels were determined to be metastable with half-lives of 0.66 mu sec and 0.06 mu sec, respectively. The transition from the level at 472.9 kev was measured to be definitely prompt to less than 0.03 mu sec. Multipolarity assignments were made based on the determined internal conversion coefficients, and spin and parity assignments to the nuclear energy levels were deduced on the basis of the transition multipolarities. The level assignments are in excellent agreement with those predicted by the Bohr-Mottelson unified model of the nucleus. The occurrence of the two metastable states as well as the rather unusual Kcapture ratios are discussed. (auth)
- Research Organization:
- Ames Lab., Ames, Iowa
- DOE Contract Number:
- W-7405-ENG-82
- NSA Number:
- NSA-13-020518
- OSTI ID:
- 4244462
- Report Number(s):
- ISC-1007
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BETA SPECTROMETERS
CAPTURE
COINCIDENCE METHODS
COLLECTIVE MODEL
DECAY
ELECTRONS
ENERGY
ENERGY LEVELS
EXCITATION
GAMMA DETECTION
GAMMA RADIATION
HALF-LIFE
INTERNAL CONVERSION
K-CAPTURE
MEASURED VALUES
METASTABLE STATES
NILSSON-MOTTELSON MODEL
NUCLEAR MODELS
PARITY
PHYSICS AND MATHEMATICS
SCINTILLATION COUNTERS
SPIN
THULIUM 169
TRANSIENTS
YTTERBIUM 169