Time-of-flight direct geometry spectrometer 4SEASONS at J-PARC

Kajimoto, Ryoichi  ; Nakamura, Mitsutaka   ; Kamazawa, Kazuya*; Inamura, Yasuhiro  ; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Ishikado, Motoyuki*; Murai, Naoki  

4SEASONS is a time-of-flight direct geometry chopper spectrometer in the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC). It is designed for measurements of dynamics in the 10-10 meV energy range. The momentum-energy region for this spectrometer occupies the middle of the momentum-energy space covered by all MLF spectrometers. Compared with the other chopper spectrometers in MLF, 4SEASONS is designed to supply high thermal neutron flux by relaxing the resolution to observe weak inelastic signals. Although strongly correlated electron systems and magnetism dominate 80% of the experiment proposals, a sizable number of proposals belong to other research fields such as thermoelectric materials and catalysts. In this paper, we will show recent improvements of the instrument as well as examples of scientific outputs.