L TO K RATIOS IN THE ELECTRON CAPTURE DECAY OF W$sup 181$ AND Ta$sup 17$$sup 9$
The L to K ratios in the electron capture decay of the isotopes Ta/sup 179/ and W/sup 181/ have been redetermined. Thin (0.060 in.) NaI crystals with thin (0.002 in.) Be windows were used to detect the L and K x rays. The partial fluorescence yields of the L subshells of Hf and Ta were also measured by determining the coincidence rates between the L and the K x rays emitted by the sources. It is necessary to know the fluorescence yields if the L to K ratios are to be determined from the measured intensities of the L and the K x rays. The L to K ratio of Ta/sup 179/ was found to be 0.63 plus or minus 0.06, which implies a total decay energy of approximately 115 plus or minus 5 kev for this isotope. This energy is consistent with the observation that no gamma rays accompany the decay of Ta/sup 179/ since the first excited level of Hf/sup 179/ has an energy (122 kev) exceeding the total decay energy of Ta/sup 179/. The L to K ratio of W/sup 181/ was foun d to be 0.23 = 0.05, from which a decay energy of approximately 260 kev is computed. This result is in agreement with the fact that two weak gamma rays are emitted by the source, one at 137 kev and the other at 152 kev. These gamma rays correspond to excited levels in Ta/sup 181/. These gamma rays are in coincidence with the L x rays emitted by the source but not with the K x rays, which means that the total decay energy of Wi8i must exceed 166 kev. The L to K capture ratios reported are not in good agreement with previously reported values. (auth)
- Research Organization:
- Univ. of California, Livermore
- NSA Number:
- NSA-15-032767
- OSTI ID:
- 4824007
- Report Number(s):
- UCRL-6207; 0031-899X
- Journal Information:
- Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D, Journal Name: Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D Vol. Vol: 124; ISSN PHRVA
- Country of Publication:
- United States
- Language:
- English
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