An improved Feynman-α correlation analysis with a moving-bunching technique

The bunching technique has been widely utilized in Feynman-α neutron correlation analysis to synthesize neutron counts of longer gate widths by bunching neutron counts stored in adjacent MCS channels. An alternative technique referred to as "moving- bunching technique" was proposed to reduce a statistical scatter of variance-to-mean ratio of neutron counts. The conventional bunching technique has no overlap of adjacent bunches, while the present technique has a much longer overlap to filter white noise similarly to the moving-average technique. A Feynman-α experiment was performed in the UTR-KINKI, to confirm the applicability and advantage of the proposed bunching technique. When a neutron detector was placed far from the core, a Feynman-α analysis with the conventional bunching technique led to a scattered variance-to-mean ratio from which prompt-neutron decay constant was never determinable. However, another analysis with the proposed moving-bunching technique gave a successful result even for such a remote detector. For a neutron detector close to the core, the proposed technique resulted in a slight reduction of statistical error of the decay constant. (author)