Theory of Feynman-alpha technique with masking window for accelerator-driven systems

•A theory of the modified Feynman-alpha technique for the ADS was developed.•The experimental conditions under which this technique works were discussed.•It is expected this technique is applied to the subcriticality monitor for the ADS.

Recently, a modified Feynman-alpha technique for the subcritical system driven by periodically triggered neutron bursts was developed. One of the main features of this technique is utilization of a simple formula that is advantageous in evaluating the subcriticality. However, owing to the absence of the theory of this technique, this feature has not been fully investigated yet. In the present study, a theory of this technique is provided. Furthermore, the experimental conditions under which the simple formula works are discussed to apply this technique to the subcriticality monitor for the accelerator-driven system.