4SEASONS; A High-intensity chopper spectrometer for inelastic neutron scattering at J-PARC/MLF

Kajimoto, Ryoichi  ; Nakamura, Mitsutaka   ; Yokoo, Tetsuya*; Nakajima, Kenji   ; Inamura, Yasuhiro; Takahashi, Nobuaki; Maruyama, Ryuji   ; Soyama, Kazuhiko  ; Shibata, Kaoru  ; Suzuya, Kentaro; Nakatani, Takeshi ; Sato, Setsuo*; Mizuno, Fumio; Ito, Yukihiro; Iwahashi, Takaaki; Kambara, Wataru; Tanaka, Hiromichi; Yoshida, Noboru; Aizawa, Kazuya  ; Arai, Masatoshi; Niita, Koji*; Shamoto, Shinichi  ; Yamada, Kazuyoshi*

4SEASONS is one of the neutron chopper spectrometers in J-PARC/MLF. It is intended to provide very high counting rate up to 300 meV neutron energy with medium resolution (% at ) to efficiently collect weak inelastic signals from novel spin and lattice dynamics especially in high- superconductors and related materials. To achieve this goal, the spectrometer equips advanced instrumental design such as an elliptic-shaped converging neutron guide coated with high- (-4) supermirror, long-length (2.5 m) He PSDs arranged cylindrically inside the vacuum scattering chamber. Furthermore, the spectrometer is ready for multi-incident-energy measurements by the repetition rate multiplication method with a special Fermi chopper, and polarization analysis with He spin filters. 4SEASONS is now under construction and will be ready to use in December 2008. In this paper, we show the design of 4SEASONS and current status of its construction.