Experimental investigations of dead-time effect on Feynman-α method

The variance-to-mean measurements were carried out in the ex- and in-core experiments to demonstrate the validity and applicability of the improved expression for data analysis, which was derived by considering the dead-time effect of neutron counter. In the ex-core experiment, the validity of the dead-time term, which was added to the conventional expression for the consideration of the dead-time effect, could be confirmed, and the dead time of the counter employed was also determined. In the in-core (Feynman-α) experiment, it is confirmed that both the inherent decay constant and the dead time could be obtained by the application of the improved expression to data analysis. The above results indicate that the improved expression is available for the data analysis of the Feynman-α experiment performed under high-count-rate conditions.