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., σ₀^ƒ (effective) = 561.5 b and I^ƒ = 268 b. For the resonance integral measurements, the low-energy cutoff has been adjusted to 0.625 eV. The measured cross sections are:

Isotope    σ₀^ƒ(b)    I^ƒ(b)

²⁴⁴Cm    1.1 ± 0.5    18.0 ± 1.0

²⁴⁵Cm    2018 ± 37    772 ± 40

²⁴⁶Cm    0.17 ± 0.10    10.0 ± 0.4

²⁴⁷Cm    82 ± 5    778 ± 50

²⁴⁸Cm    0.34 ± 0.07    13.2 ± 0.8

²⁴⁹Cf    1660 ± 50    2114 ± 70