Energy- and -resolution investigations of a chopper spectrometer 4SEASONS at J-PARC

Iida, Kazuki*; Ikeuchi, Kazuhiko*; Ishikado, Motoyuki*; Suzuki, Junichi; Kajimoto, Ryoichi  ; Nakamura, Mitsutaka   ; Inamura, Yasuhiro  ; Arai, Masatoshi

4SEASONS is one of the inelastic neutron scattering instruments in the pulsed neutron facility in J-PARC. It utilizes a Fermi chopper to monochromate the neutron beam generated incident on a sample and a large-area detector system to detect the scattered neutrons as functions of position and time, and analyzes the momentums and energies of excitations in the sample with the time-of-flight technique. The instrument has been developed to perform high-efficiency measurements of weak inelastic signals on novel spin and lattice dynamics in the energy region of 10 - 10 meV. The ability to utilize multiple incident-energies simultaneously, in addition to the recent improvement in the signal-to-noise ratio, has made 4SEASONS one of the best chopper spectrometers in the world. In the presentation, we will show the recent scientific outputs and upgrades of the instrument.