Development of the Chopper spectrometer 4SEASONS at J-PARC

Kajimoto, Ryoichi  ; Yokoo, Tetsuya*; Nakajima, Kenji  ; Nakamura, Mitsutaka   ; Inamura, Yasuhiro; Maruyama, Ryuji   ; Soyama, Kazuhiko  ; Suzuya, Kentaro; Ino, Takashi*; Oyama, Kenji*; Aizawa, Kazuya  ; Arai, Masatoshi; Niita, Koji*; Imai, Yoshinori; Kodama, Katsuaki   ; Asaoka, Hidehito  ; Shamoto, Shinichi  ; Hiraka, Haruhiro*; Fujita, Masaki*; Yamada, Kazuyoshi*

4SEASONS is a chopper-type inelastic neutron spectrometer, and one of the day-one instruments at the spallation neutron source facility in Japan Proton Accelerator Research Complex (J-PARC). The targeted energy range is 5-300meV, and the spectrometer is optimized in intensity in this energy range by moderating the resolutions (% at ), by incorporating an efficient beam transport system, and by realizing multi incident energy () measurement. The high intensity and efficiency available at 4SEASONS make this spectrometer suitable for study of novel quantum phenomena in high- superconductors and related systems. In the present paper, we will report the current status of the development and the construction of 4SEASONS, such as construction of the vacuum tank and the shielding, development of the new Fermi chopper for the multi- measurement, 2.5m-long He PSDs, and the beam transport system.