Starting-up of the chopper spectrometer 4SEASONS in J-PARC

Kajimoto, Ryoichi  ; Nakamura, Mitsutaka   ; Yokoo, Tetsuya*; Inamura, Yasuhiro; Mizuno, Fumio; Nakajima, Kenji  ; Takahashi, Nobuaki; Kawamura, Seiko   ; Maruyama, Ryuji   ; Soyama, Kazuhiko  ; Shibata, Kaoru  ; Suzuya, Kentaro; Nakatani, Takeshi ; Sato, Setsuo*; Ito, Yukihiro; Iwahashi, Takaaki; Kambara, Wataru; Tanaka, Hiromichi; Katabira, Asahiko*; Yoshida, Noboru; Aizawa, Kazuya  ; Arai, Masatoshi; Wakimoto, Shuichi  ; Shamoto, Shinichi  ; Fujita, Masaki*; Hiraka, Haruhiro*; Oyama, Kenji*; Yamada, Kazuyoshi*

4SEASONS is a Fermi chopper spectrometer for the spallation neutron source in MLF, J-PARC. It is intended to provide 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. For this purpose, the spectrometer is equipped with advanced instrumental design such as an elliptic-shaped converging neutron guide, long (2.5 m) position sensitive detectors, and a Fermi chopper feasible for multi-incidnent-energy () measurement. The spectrometer accepted the first neutron beam on September 2008, and its first inelastic scattering data was produced on June 2009. Furthermore, the spectrometer successfully demonstrated the usefulness of the multi- measurement. In this paper, we show the design and current status of 4SEASONS, and some experimental results.