Measurements of the 14 MeV fission cross-sections for /sup 235/U and /sup 239/Pu
The fission cross-sections of /sup 235/U and /sup 239/Pu have been measured at a neutron energy of 14.63 MeV. A 150 kV accelerator, installed on a low mass floor at the center of a large laboratory, provided a source of D-T neutrons under conditions of low scattering. Fission events were accumulated with the target foils and detectors positioned inside a vacuum chamber and at various distances from the neutron source. Fission fragments passing through a limited solid angle aperture were registered on polyester track-etch films. The masses of the foil deposits were previously determined by microbalance weighings and confirmed by thermal fission and ..cap alpha.. counting. The angular distribution of fission fragments for /sub 2//sup 35/U and /sup 239/Pu were measured in a separate experiment. In this case the fission fragments were detected by a polyester track-etch film which was shaped to cover a 110/sup 0/ arc on a sphere of 5.08 cm raidus centered on the deposit. The neutron flux was measured relative to /sup 56/Fe(n,p)/sup 56/Mn and /sup 27/Al(n,..cap alpha..)/sup 24/Na reaction cross-sections. /sup 56/Mn and /sup 24/Na activities were measured in a 4..pi beta.. gas flow proportional counter. The absolute efficiencies were separately measured using a 4..pi beta..-..gamma.. coincidence counting technique. The room scattered flux contribution to the total flux was determined from different source-detector spacing runs. The precise neutron energy was directly measured using a silicon surface barrier detector. The cross-sections obtained for /sup 235/U(n,f) and /sup 239/Pu(n,f) reactions were 2.070 +/- .046 and 2.44 +/- .092 respectively and a /sup 239/Pu(n,f)//sup 235/U(n,f) cross-section ratio of 1.179 +/- .028.
- Research Organization:
- Michigan Univ., Ann Arbor (USA)
- OSTI ID:
- 7095704
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
A=220 & above
Experimental-- Spontaneous & Induced Fission-- (-1987)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ANGULAR DISTRIBUTION
BARYON REACTIONS
CROSS SECTIONS
DATA
DISTRIBUTION
ENERGY RANGE
EXPERIMENTAL DATA
FAST FISSION
FISSION
FISSION FRAGMENTS
HADRON REACTIONS
INFORMATION
MEV RANGE
MEV RANGE 10-100
NEUTRON FLUX
NEUTRON REACTIONS
NUCLEAR FRAGMENTS
NUCLEAR REACTIONS
NUCLEON REACTIONS
NUMERICAL DATA
PLUTONIUM 239 TARGET
RADIATION FLUX
TARGETS
URANIUM 235 TARGET