Measurements of the Neutron Fission and Absorption Cross Sections of ²³⁹Pu Over the Energy Region 0.02 eV to 30 keV

The neutron absorption and fission cross sections for ²³⁹Pu have been measured simultaneously over the neutron energy range from 0.02 eV to 30 keV. An electron linear accelerator was used to produce a source of pulsed neutrons which are collimated to impinge on the ²³⁹Pu sample located at the center of a large liquid scintillator. The prompt gamma rays resulting from fission or from neutron capture were detected using the large liquid scintillator. A fission event was measured in one case by using an ionization chamber containing ²³⁹Pu. In another case using metal foils of ²³⁹Pu, a technique depending upon the difference in the shape of the pulse height distributions for the prompt gamma rays from fission and capture was used to distinguish fission events. The data were normalized at 0.025 and 0.3 eV using data previously reported. A brief description of the experiments is given and a comparison of the present data with previously published data is given.