Radiative capture-to-fission cross-section ratio for 239Pu in the neutron energy range from 0,2 to 30 keV

Radiative capture-to-fission (α) have been measured for 239Pu. Measurements have been made by a neutron lead slowing-down method. The method has the following essential features: 1) Neutron scattering does not change isotropic neutron field of the spectrometer. The consequence is a steady background of the detector. 2) Detection of capture and fission events in the sample is carried out by a proportional α-detector. Efficiency of the α-detector is proportional to the total energy of α-quanta, emitted on capture and fission and it does not depend on the spectral picture. 3) Screening for thermal neutrons in utilized samples is small and taken exactly into account. Measurements have been carried out on ''thin'' (anti n = 4,2x 1020 at x cm-2) and ''thick'' (anti n = 4,9x 1021 at x cm-2) plutonium samples. The data obtained over α and fission cross section sigmasub(f), averaged over neutron energy levels are given in the table. Comparison is made and presented graphically between the obtained averaged values of α and the results of other authors