Measurement of the Fission Cross Section of Uranium-235 for Incident Neutrons with Energies Between 2 and 100 keV

The fission cross section of ²³⁵U was measured for incident-neutron energies between 2 and 100 keV using an electron LINAC pulsed source of neutrons and the time-of-flight technique. The fission events were characterized by coincidence between the pulses of a fission chamber, placed at the center of a large scintillation tank, and gamma-ray events registered in the tank. The incident-neutron spectrum versus energy was monitored by a BF₃ ionization chamber and checked with a ⁶Li-glass neutron detector. The cross sections were normalized to a value of 31 643 b-eV for the fission integral between 2 and 10 keV.