Utilization of multiple incident energies on cold-neutron disk-chopper spectrometer at J-PARC

Nakamura, Mitsutaka   ; Nakajima, Kenji  ; Kajimoto, Ryoichi  ; Arai, Masatoshi

The efficiency of measurement on a chopper spectrometer will be significantly improved, if we can measure a number of inelastic scattering processes simultaneously. In such measurements we should deliver the multiple incident energy neutrons to the sample within a pulse period of the source. This method was proposed by Mezei and referred to as Repetition Rate Multiplication (RRM) measurement. Since optimizing the chopper spectrometer for monochromatic beam experiment is our first priority, the RRM measurement might be optional operation. However, even without replacing a chopper blade nor accepting very long flight path, a slight modification of the instrument design enables the RRM measurement in considerably excellent performance. In this talk, we will explain the instrument design to realize the RRM measurement on chopper spectrometers at J-PARC, and show its performance.