The decay of mass-separated ²⁰²A+ and ²⁰²Po
Date Issued
June 1, 1980
Author(s)
Ramos, Maria Paz Melebo
Advisor(s)
Carrol R. Bingham
Additional Advisor(s)
Leo L. Riedinger
Robert W. Lide
Abstract
Radioactive sources containing 202 At and 202 Po were produced in 160 bombardments of 191 Ir and 193 Ir. Multiscaled spectra of γ-rays and conversion electrons were obtained and γ-Y, γ-conversion electron coincidences were measured. On-line multiscale data were used to determine half-lives of many transitions. The difference in the half-lives of the 3.1-min 202 At ground state and the high-spin isomer was not apparent. Seventeen levels were placed in 202. Po, 11 of them previously unknown. The ground state band is observed up to the 6 + state and the coincidence data agree with earlier in-beam measurements which demonstrated the population of the 6 + state by a short-lived isomer with a half-life of 85 ns. The isomer is likely the 8 + member of the π(h9/2)2 configuration and based on a transition strength of one Weisskopf single particle unit would lie about 20 keV above the 6 + state. The level schemes are compared with a single particle-core coupling model, the simple vibrational model, and the interacting.boson model. The multiscale and coincidence data revealed 38 transitions in 202 'Bi following the decay of 45.1 min 202, 'Po, of which 29 were placed in a level scheme. The strongest γ-ray transition at 688 keV is apparently only in coincidence with the 4l and 65 keV transitions. The remaining moderately strong transitions were assigned to two other parts of the decay scheme which also could not be connected by coincidence data. The multipolarities of the transitions were measured but the uncertainties in the decay scheme and lack of knowledge of the spin of the ground state and other possible isomers made spin assignments impractical.
Degree
Master of Science
Major
Physics
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