New technique for inelastic scattering measurement is in practical use at J-PARC

新しい非弾性散乱実験法がJ-PARCで実用化

梶本 亮一  ; 中村 充孝   ; 新井 正敏

Kajimoto, Ryoichi; Nakamura, Mitsutaka; Arai, Masatoshi

Inelastic scattering measurements always face difficulty of small scattering cross section. An instrument for such measurements essentially needs monochromatic neutron beam, which is disadvantageous for the measurement of weak signal of inelastic scattering, since we waste most of the neutron beam. In other words, if we can minimize the wasted beam, we can significantly improve the measurement efficiency. One way of doing this on a chopper spectrometer at a pulsed source is to utilize more than one incident energies ('s) during one measurement. This can be achieved in principle by taking advantage of the fact that the monochromating chopper rotates much faster than the repetition frequency of the pulsed source. This is called repetition rate multiplication technique. Here, we report that we succeeded in utilizing multiple 's with the Fermi chopper spectrometer 4SEASONS at J-PARC, and proving its usefulness in measurements of of a single crystal.