Precision Measurement of Cold Neutron Flux using Alpha-Gamma

The Alpha-Gamma device at NIST utilizes the interaction of neutrons with a totally absorbing $^{10}$B target to precisely measure the flux of a monochromatic neutron beam. This measurement provides a calibration of the $^{6}$Li(n,$\alpha$)$^{3}$H based flux monitor used in the NIST neutron lifetime experiment to better than 0.1% and has been utilized in novel measurements of the $^{6}$Li neutron cross section. Measurement of other standard neutron cross sections and a recalibration of the United States’ national neutron source are underway. The results of recent measurements will be presented, and planned operations using Alpha-Gamma will be discussed.