H. Palevsky

Direct measurement of the energy variation of η for U233, U235, and PU239☆

Abstract A technique is described that measures directly the energy variation of η the number of fission neutrons produced per neutron absorbed. When combined with total cross-sections, the method is capable of giving fission cross-sections as well. Results are presented in the energy region near thermal, of importance to reactor design, for U233, U211, and Pu29. Comparison with η computed from total and fission cross-sections shows good agreement for U233 and U235 but a disagreement outside experimental error for Pu239 An auxiliary experiment demonstrates that v, the number of neutrons per fission, is constant with energy in the region of interest for Pu239 hence that the discrepancy cannot be ascribed to a v variation.

Direct measurement of the energy variation of ? for U233, U235, and Pu239

A technique is described that measures directly the energy variation of η, the number of fission neutrons produced per neutron absorbed. When combined with total cross sections, the method is capable of giving fission cross sections as well. Results are presented in the energy region near thermal, of importance to reactor design, for U233, U235, and Pu239. Comparison with η computed from total and fission cross sections shows good agreement for U233 and U235 but a disagreement outside experimental error for Pu239. An auxiliary experiment demonstrates that ν, the number of neutrons per fission, is constant with energy in the region of interest for Pu239, hence that the discrepancy cannot be ascribed to a ν variation.