Relative probabilities of the uranium isotopes for thorium x-ray emission and fluorescence of uranium x-rays
Both thorium x-rays from decaying uranium isotopes and self-fluoresced uranium x-rays are prominent in high-resolution gamma-ray spectra of uranium-bearing materials. Useful application of the information carried by those x-rays has been curtailed because the probabilities of the uranium isotopes for thorium x-ray emission and for uranium x-ray fluorescence have not been known. By analyzing enrichment-meter geometry spectra from uranium oxide standards whose enrichments ranged from 0.7% to 91%, relative values, primarily, have been obtained for the probabilities of both processes. Thorium x-ray emission is very heavily dominated by {sup 235}U. In all ordinarily occurring uranium isotopic distributions, thorium x-rays may be used as a valid {sup 235}U signature. The probability for a thorium K{sub {alpha}1} x-ray to be emitted in the decay of a {sup 235}U atom is 0.048 {plus minus}0.002. In infinitely thick uranium oxide materials, the relative ratios of effectiveness for self-fluorescence, on a per unit mass basis, are approximately {sup 234}U : {sup 235}U : {sup 236}U : {sup 238}U = 1.13 : 1.00 : 0.52 : 0.028. on a per decay basis, the approximate ratios are 0.00039 : 1.00 : 0.017 : 0.18. These results imply that, contrary to what has often been stated, gamma rays are far more important than alpha particles in the self-fluorescence of uranium. Because of the importance of gamma-ray self-fluorescence, the uranium x-ray yield will be somewhat influenced by the size, shape, and composition of the materials. 4 refs., 1 fig.
- Research Organization:
- Los Alamos National Lab., NM (United States)
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 5428562
- Report Number(s):
- LA-UR-91-2463; CONF-910774--31; ON: DE91016235
- Country of Publication:
- United States
- Language:
- English
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ACTINIDE COMPOUNDS
ACTINIDE ISOTOPES
ACTINIDES
CHALCOGENIDES
CHEMICAL ANALYSIS
DECAY
ELEMENTS
FLUORESCENCE
GAMMA SPECTRA
ISOTOPES
LUMINESCENCE
MANAGEMENT
METALS
NONDESTRUCTIVE ANALYSIS
NUCLEAR MATERIALS MANAGEMENT
OXIDES
OXYGEN COMPOUNDS
PARTICLE DECAY
PROBABILITY
RADIATIVE DECAY
SPECTRA
THORIUM
URANIUM COMPOUNDS
URANIUM ISOTOPES
URANIUM OXIDES
X-RAY EMISSION ANALYSIS
X-RAY SPECTRA