243Am neutron fission cross section and resonance parameters

Abstract

The SVZ-100 lead moderation time neutron spectrometer at the Institute of Nuclear Physics of the Russian Academy of Sciences was used to measure the fission cross section for 243 Am in the neutron energy range E n = 0.3 eV -10 keV. The resonance fission integrals and the area and fission width of the resolved resonances were calculated. The properties of the intermediate-structure resonances were evaluated. The results were compared with existing data and recommended evaluations.Subbarrier fission cross section of 243 Am in the resonance neutron energy range and the properties of the resonances have not been studied sufficiently to construct reliable data libraries which are necessary to study the transmutation of wastes and to improve models of transitional states in the theory of fission of heavy nuclei.The present work was performed as part of research on the fission of transuranium nuclei using the SVZ-100 lead moderation time neutron spectrometer at the Institute for Nuclear Research of the Russian Academy of Sciences (IYaI RAN) [1][2][3][4][5]. Even though their resolution is low, such spectrometers are successfully used to measure nuclide cross sections which are difficult or impossible to study by other methods [6,7]. In the present work, the fission cross section was measured and the area and width of the 243 Am fission resonances were determined for neutron energies below 10 keV.Experimental and Recommended Data. The main information on the fission cross section at the resonance neutron energies is obtained by time-of-flight methods in the following works. In the USA (Los Alamos), an experiment was performed at energies above 49 eV using neutrons from the Pommard nuclear explosion. The average error in the data was 20% [8]. In Germany (Karlsruhe), the cross section was measured in an electrostatic accelerator in the energy range 5 < E < 250 keV relative to the 235 U fission cross section with error 8-10% [9]. In Belgium (Geel), the measurements were performed relative to the 235 U cross section in an electrostatic accelerator in the energy range 0.33 < E < 10 MeV and in the linear electron accelerator GELINA in the energy range 1 eV < E < 1.5 MeV. The fission area was found and the fission width Γ ƒ determined for 31 resonances [10].At the Kyoto University (Japan), the 243 Am fission cross section was measured in the neutron energy range 0.05 eV -10 keV using the KULS lead moderation time neutron spectrometer and linear electron accelerator. The measurements were performed relative to the 235 U fission cross section, the target mass was 134 μg, the error was 4.5-7% in the range