Detector area expansion at iNSE neutron spin echo spectrometer

Expansion of a detection area is an effective method to increase the measurement efficiency of a neutron spin echo (NSE) spectrometer as well as other spectrometers. For this purpose, we installed a new π/2 spin flipper and Fresnel coil of iNSE spectrometer at JRR-3, Tokai, Japan, for wide-area data acquisition. In this study, we propose a data reduction method to correct the phase inhomogeneity due to the path difference of neutrons on the large detection area. This method can convert many NSE signals at small areas to one NSE signal at a large area with taking the phase offset due to the phase inhomogeneity into account. The measurement efficiency increased by approximately one order of magnitude as a result of the detection area expansion.