Measurement of the U235 Neutron Capture-to-Fission Ratio, α, for Incident Neutron Energies from 3.25 eV to 1.8 keV

Abstract

The ratio of the neutron capture cross section to the fission cross section, α, for U235 has been measured for incident neutron energies from 3.25 eV to 1.8 keV. A pulsed and collimated neutron beam was passed through a U235 fission chamber placed at the center of a large liquid scintillator, and both capture and fission events in the chamber were detected in the scintillator by means of their prompt gamma rays. A fission event was distinguished from a capture event by a coincidence of the scintillator signal with a signal from the fission chamber. The values of α obtained, after various efficiency and background corrections were applied, are in good agreement with data derived from other experiments.