Inelastic scattering measurement option of TOF-USANS instrument at J-PARC

In a TOF-USANS instrument based on a double crystal diffractometer of Si perfect crystals with (1 1 1) fundamental reflection, monochromatic neutrons of wavelength λ and its harmonics (λ/n, n=3,4,5,7) by the first crystal enter a sample, and scattering beams from the sample are analyzed by the second crystal. The neutron beams of these entire wavelengths are used in the normal mode to measure USANS intensity effectively. On the other hand, the TOF-USANS instrument would be considered to be a crystal-monochromator-type direct geometry inelastic-instrument, including the analysis by the second crystal. Therefore, by installing a band definition chopper to choose specific wavelength as option, it would be thought that quasi-elastic and inelastic scattering measurements become possible.