An Effective Capture Cross Section of Np²³⁹ for Thermal Reactor Neutrons

Depleted uranium was irradiated in the thermal neutron flux of the Low Intensity Test Reactor at Oak Ridge National Laboratory. From mass spectrographic analysis of Pu²⁴⁰ and from chemical determination of Pu content, the effective capture cross section (including both thermal and epithermal neutron capture) was determined for Np²³⁹ to be 80 ± 15 barns.