Radiative Capture

Radiative neutron capture cross sections are being measured as a function of neutron energies between a few keV and about 3 MeV. Since neutrons are absorbed unproductively in radiative neutron capture, the cross section data are needed in order to evaluate materials proposed for use in reactor structure and control. The experimental technique is the activation method in which a sample is irradiated in a monoenergetic neutron beam and counted with a beta or gamma-ray counter. The monoenergetic neutrons are produced by bombarding lithium or tritium targets with protons from the Van de Graaff accelerator. The neutron intensity is measured with a fission chamber which counts fissions in a thin deposit of ²³⁵U.