The 90-keV transition in Ru99 is a very interesting, but as yet little exploited, case for recoilfree resonance studies. The multipolarity of the transition is a mixture of magnetic dipole and electric quadrupole, with a mixing ratio δ2 = 2.7. The half life of 20 nsec results in a linewidth to gamma-energy ratio which is somewhat smaller than that for the case of Fe57. The level in Ru99 is fed in the decay of 16-day Rh99 which is produced by p,n reaction on Ru99. A source host of ruthenium gives an unsplit emission line with a recoilfree fraction of ~15% at 4.2°K. By bombarding enriched isotope and doing a chemical separation, high specific activity sources in the several millicurie range can be prepared. The complex magnetic hyperfine spectrum of 18 lines resulting from the 3/2 → 5/2 transition can be completely resolved in the 500 kG.field which acts on the ruthenium nucleus situated in an iron host. By making use of accidental separation of left and right circularly polarized hyperfine components, it is possible to measure the sense and magnitude of relatively small aligned fields acting on the ruthenium nuclei. Details of source and absorber preparation are presented.
KeywordsSource Host Nonresonant Background Ruthenium Metal Magnet Arrangement Drive Tube
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- 2.R. P. Elliott, Constitution of Binary Alloys, Ist Supplement ( McGraw-Hill, New York, 1965 ), p. 431.Google Scholar