The slow chopper installed at BRl was used to make an accurate determination of the binary-to- ternary fission ratio for U235 in the neutron-energy range from 0.005 eV to 0.2 eV. Large gold-silicon surface-barrier detectors are used for the consecutive measurement of long-range a-particles (absorber in) and fission fragments (absorber out). The time analysis is done with a 100-channel time-of-flight analyser. A one metre flight-path and a rotor speed of 50 rev/s is used. The B/T ratio was also measured with a high statistical accuracy (about 1% in intense beams with well defined neutron spectra, i.e. a "cold neutron" beam, a beam extracted from a thermal column and a beam of 0.3-eV neutrons produced by crystal diffraction. The B/T ratio exhibits a small and smooth variation in the energy range considered. This effect seems to be correlated with measurements of some other fission parameters in the same neutron-energy range.
Original language | English |
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Publisher | SCK CEN |
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Number of pages | 14 |
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State | Published - Mar 1965 |
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Name | SCK CEN Reports |
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Publisher | SCK CEN |
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No. | BLG-386 |
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