Correction of flight departure time using moderator time response characteristics

Yamamoto, Kazuyoshi ; Xu, P. G.   ; Oikawa, Kenichi   ; Harada, Masahide   ; Inamura, Yasuhiro  ; Nakamura, Mitsutaka   ; Kodama, Katsuaki   

TOF neutron diffractometers typically use t (time between neutron detection and target collision) as flight time. However, this is inaccurate due to moderator thermalization time after initial neutron slowing. We developed a patent-filed correction method to obtain a more accurate flight time. This involves pre-calculating the moderator's time response using neutron transport calculations and subtracting a delay time from t for each event. We validated this using data from J-PARC MLF-BL10 (NOBORU) and Rietveld analysis. Results show the correction reduces the coefficient of the quadratic term in the calibration equation (as determined by Rietveld analysis), improving linearity. Originally designed for small-scale sources, this method can be applied to larger facilities, contributing to the overall accuracy of TOF neutron diffraction, and this correction allows for more accurate measurements.