He neutron reaction cross sections using the Alpha-Gamma Device.*

The Alpha-Gamma device at the National Institute of Standards and Technology utilizes the interaction of neutrons with totally absorbing ¹⁰B targets to precisely measure the absolute flux of a monochromatic neutron beam. This absolute measurement does not require knowledge of neutron cross sections, reaction branching ratios, or the neutron beam energy. The device is being utilized in novel measurements of the ²³⁵U(n,f) neutron-induced fission reaction and ⁶Li(n,α)³He reaction cross sections in an effort to provide systematically independent determinations of these important quantities with comparable uncertainties. The results of recent and ongoing measurements will be presented, and planned operations will be discussed.