RADIOACTIVE DECAY OF IRIDIUM$sup 18$$sup 9$
To produce radioactive Ir/sup 189/ a cyclotron bombardment with 10 Mev protons was performed on a target sample of osmium enriched in the isotope Os/sup 189/ to a composition of 87.3%. Also present (8.5% composition) was the isotope Os/sup 190/ which would be expected to react with the protons to produce the Ir/ sup 190/ activity with a half life about equal to that of Ir/sup 189/. A low energy proton bombardment (6 Mev) was performed on an osmium sample enriched to 95% in Os/sup 190/ The radiations from both bombardments were observed with several types of scintillation detectors and pulse height analyzers and compared over a period of four months. A typical spectrum of radiation from the enriched Os/sup 190/ target showed photo peaks for an x-ray energy of 63 kev, a strong 187 kev gamma ray, and numerous other higher energy gamma rays. The half life was measured to be 12.1 plus or minus 0.2 days. The early radiation from the enriched Os/sup 189/ target contained many gamma rays with a 41-hour half life that was identified as the well-known Ir/sup 188/ decay and therefore attributed to a (p,2n) reaction with the Os/sup 189/. The spectra of later radiations were compared under identical conditions of source to crystal geometry and analyzer gain settings with the spectra of radiation emitted by the enriched Os/sup 190/ target samp1e. The Os/sup 190/ target spectrum was then used to subtract from the Os/sup 189/ target spec trum all radiation due to this impurity. The resuiting spectrum showed only a strong 63 kev x-ray photo peak and a strong 245 kev photo peak. The spectrum was further unscrambled by subtracting other gamma rays whose energies were previously determined. On the basis of multipolarity assignments and some conversion electron intensities, it was possible to use the gamma ray intensity measurements obtained from the unscrambling calculations and the K and L x-ray measurements to construct a decay scheme for Ir/sup 189/. The branching ratios and the transition intensities were computed and the excited energy levels of Os/sup 189/ with their spin and parity assignments were proposed. The energy levels were set at 30.9, 69.6, 106, 164, 219, 269, and 275 kev. The half life of the K capture Ir/sup 189/ decay was measured to be 13.3 plus or minus 0.1 days.
- Research Organization:
- Ohio State Univ., Columbus
- NSA Number:
- NSA-16-033813
- OSTI ID:
- 4778831
- Journal Information:
- Dissertation Abstr., Journal Name: Dissertation Abstr. Vol. Vol: 23
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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