Measurement and Normalization of the Relative Plutonium-241 Fission Cross Section in the Thermal and Low-Resonance Energy Region

The neutron-induced fission cross section of ²⁴¹Pu was measured at an 8-m-long flight path of the CBNM Linac from 50 to 0.01 eV, allowing a direct normalization to the 2200 m/sec reference cross section. The fission reaction rate and the neutron flux were determined simultaneously with surface barrier detectors placed on each side of back-to-back ²⁴¹Pu and ¹⁰B layers. The fission cross section was calculated assuming a 1/v behavior of the ¹⁰B(n,α)⁷ Li cross section. Several fission and resonance integrals were calculated from the normalized σ_f versus energy curve and compared with other results. Also, the 20.44°C Westcott factor, g_f, was calculated to be 1.046 ± 0.006.