Reactor Noise Analysis by Photon Observation

A set of moment equations is given for a reactor system in which neutron fluctuations are observed by detecting high-energy prompt photons that arise from neutron interactions. Attention is restricted to a one-speed “point-reactor” model in which delayed neutrons and photons are ignored. Expressions for the ratio of the variance to mean of the particles arising from the detection of photons are computed, as well as for the power spectral density of the detection rates. Comparison of these results with the corresponding expressions from conventional neutron-detecting noise analysis shows a striking similarity, and it is suggested that noise analysis by photon detection possesses certain other characteristics that endorse its feasibility in principle.