Fission Cross Sections for Five Isotopes of Curium and Californium-249

Abstract

Thermal-neutron fission cross sections and fission resonance integrals were measured for 249Cf and five isotopes of curium with both dual fission chambers and plastic fission track recorders. Measurements were made in the thermal column and core of the SP research reactor. Cross sections were determined through direct comparison with the appropriate 235U fission cross sections, i.e., σ0ƒ (effective) = 561.5 b and Iƒ = 268 b. For the resonance integral measurements, the low-energy cutoff has been adjusted to 0.625 eV. The measured cross sections are:Isotope σ0ƒ(b) Iƒ(b)244Cm 1.1 ± 0.5 18.0 ± 1.0245Cm 2018 ± 37 772 ± 40246Cm 0.17 ± 0.10 10.0 ± 0.4247Cm 82 ± 5 778 ± 50248Cm 0.34 ± 0.07 13.2 ± 0.8249Cf 1660 ± 50 2114 ± 70