Prompt Neutron Periods of Metal Critical Assemblies

Measurement of the time distribution of pairs of counts due to neutrons originating from a common ancestor in a neutron chain, yields a value for the prompt neutron period of a near-critical system. Such measurements can be used to establish the mass or control increment between delayed and prompt critical and, hence, constitute a reactivity calibration without use of the Inhour relation. Measurements are reported for several simple metal critical assemblies.