ON THE THEORY OF PROMPT-DECAY CONSTANTS AND CORRELATED SPECTRA IN MULTIPLYING MEDIA. PART II
Journal Article
·
· Nukleonik (West Germany) Discontinued with vol. 12
OSTI ID:4008420
Under the assumption of a cut-off energy for upscattering processes a rigorous separation of the thermal and the slowing-down range was performed. A good approximation of the eigenvalue problem restricted to the thermal region could be formulated with a feedback function including an integral representation of the reactions involved in the slowing-down process. This form was especially useful for the discussion of the decay constant as well as for the derivation of approximate formulas for the eignevalue and the effective absorption in the spectrum in a prompt decaying eigenstate. Performing a B/sup 2/ series expansion resulted in a zero order decay constant equal to (1--k/sub p,0/) 1/l/sub 0/ with the lifetime being the sum of slowingdown time and the thermal lifetime, appropriately reduced for nonthermal neutron cycles. The main contribution of the second order approximation is the importance weighting of the sum of the mean square displacements in the fast and thermal region by the corresponding lifetimes. It appears impossible to express the decay constant as a function of k/sub eff/ and l only with the lifetime defined as the reciprocal loss probability per sec. The form of the decaying thermal spectrum corresponds approximately to a stationary spectrum with 1/v-absorption of the strength
- Research Organization:
- Entwicklungsabteilung der Interatom, Bensberg, Ger.
- NSA Number:
- NSA-18-021150
- OSTI ID:
- 4008420
- Journal Information:
- Nukleonik (West Germany) Discontinued with vol. 12, Journal Name: Nukleonik (West Germany) Discontinued with vol. 12 Vol. Vol: 6; ISSN NUKKA
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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