Measurement of neutron coherent inelastic scattering by TOF inverse filter method

The TOF inverse filter method for the study of neutron inelastic scattering was investigated. The present study was carried out with a filter spectrometer for measuring single crystals. A BeO block was set between a sample and the counter as the filter spectrometer. The transmission through the filter decreases rapidly above the cut-off energy (3.65 MeV), and is a constant value 10-5 above 10 to 20 MeV. The TOF pattern of Cu measured at theta = 1100 by the TOF inverse filter method was obtained, and three peaks are seen in the pattern. Another pattern measured at theta = 900 showed 4 peaks. The TOF spectrum of Fe (3.4 wt.% Si) single crystal was also obtained. Four sharp peaks are seen. Two low energy peaks are due to the T and L mode phonons, and the high energy peaks are due to the spin waves. As a result, it can be said that the intensity of peaks is almost same in both low and high energy peaks. The intensity of high energy peaks does not decrease by this method, and this is due to the use of pulsed white neutron beam. (Kato, T.)