Current status of the 4SEASONS spectrometer at J-PARC

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

4SEASONS is one of the day-one chopper spectrometers for the spallation neutron facility in Japan Proton Accelerator Research Complex (J-PARC). The spectrometer targets high- superconductors and related strongly correlated materials utilizing incident energies of 5-300 meV. 4SEASONS supplies high flux at a sample by moderating the resolution (-6% at ) and incorporating efficient neutron optic devices. A new Fermi chopper is designed to multiply the measurement efficiency by repetition rate multiplication (RRM). Recently, we have decided to enlarge the detector coverage by in horizontal direction (with the maximum scattering angle being ) to let the spectrometer have more flexibility. The designing of the vacuum scattering chamber has been almost completed. Examination of the 2.5m-He PSD on neutron beam and manufacturing of a prototype of a slit package of the new chopper are going on.