TIME-OF-FLIGHT FISSION STUDIES ON U$sup 233$, U$sup 235$, AND Pu$sup 23$$sup 9$
The prompt mass and kinetic energy distributions resulting from the thermal neutron fission of U/sup 233/, U/sup 235/, and Pu/sup 239/ have been reinvestigated using time-of-flight methods to measure simultaneously the velocities of the fragment pairs. A new feature shown is the existence of fine structure in the prompt mass yields. This fine structure is most pronounced at high total kinetic energies where rhe fragments have little excitation energy and may be associated with irregularaties in the energy release as a function of mass. The fine structure is most noticeable in U/sup 235/ and least in Pu/sup 239/; the fragments of U/sup 235/ have the lowest average excitation and those of Pu/sup 239/, the highest. Another feature is the large drop in total kinetic energy when the fragments are near symmetry. This decrease is about 35 Mev and is consistent either with a picture in which the nucleus with 50 protons is especially preferred or with one in which fragments at symmetric fission have an abnormally high excitation energy and a consequent large number of neutrons. The mean kinetic energies for thermal neutron fission of U/sup 233/, U/sup 235/, and Pu/sup 239/ were found to be 167.6, 168.3, and 175.0 Mev with an error of plus or minus 1.7 Mev. (auth)
- Research Organization:
- Atomic Energy of Canada Ltd., Chalk River, Ont.
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-17-005334
- OSTI ID:
- 4769100
- Journal Information:
- Canadian Journal of Physics (Canada), Journal Name: Canadian Journal of Physics (Canada) Vol. Vol: 40; ISSN CJPHA
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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