Search

During the last several years, the measurements of neutron-induced fission cross-sections of actinides and stable isotopes have been performed at the GNEIS facility. At present moment, the new series of experiments for measurements of fission cross-section ratios relative to 235 U have been began for 240 Pu, 243 Am and nat W in a wide energy range of incident neutrons from 1 MeV to 200 MeV. The measurements were performed using the multiplate ionization chamber and time-of-flight technique. The first results of this measurement in case of 240 Pu and 243 Am are presented in comparison with the other data.

The description of an experimental set-up for neutron multiplicity measurements and its specific data processing procedures are presented together with some results for 252 Cf ( sf ) . With this experimental set-up the light and heavy fission fragment kinetic energies for every fission event can be registered simultaneously with the number of prompt neutrons emitted by each of the complementary fission fragments. The proposed data processing makes it possible to perform the reconstruction of pre-neutron fission fragment masses and kinetic energies as well as the initial neutron multiplicity distribution.

A description of GNEIS- the Gatchina neutron time-of-flight spectrometer at the 1 GeV proton synchrocyclotron-is given together with its basic parameters, as well as a comparison with other modern pulsed neutron source facilities. The integral neutron yield from a lead target is 3 × 10 14 n s . The spectrometer has five flight paths and a data acquisition system equipped with a few autonomous measuring stations. Some results of the (n, γf) experiments and neutron capture cross section measurements are presented to illustrate the facility's performance.

Experimental results of systematic studies of the space parity violation effect in heavy nucleus fission induced by transversally polarized monochromatic neutrons with the energies less then ~ 2 eV have been presented. Modern explanations of the results obtained and perspectives of the further investigations are discussed.