Current status of a TOF-Laue single crystal neutron diffractometer SENJU

Ohara, Takashi   ; Kiyanagi, Ryoji  ; Nakao, Akiko*; Hanashima, Takayasu*; Munakata, Koji*; Moyoshi, Taketo*; Kuroda, Tetsuya*; Kaneko, Koji   ; Tamura, Itaru  ; Oikawa, Kenichi   ; Kawasaki, Takuro   ; Yamauchi, Yasuhiro; Kawamura, Seiko   

SENJU, a TOF-Laue single crystal neutron diffractometer at the BL18 of MLF/J-PARC, was designed for precise crystal and magnetic structure analyses under multiple extreme environments such as low-temperature, high-pressure and high-magnetic field, and also capable of taking diffraction measurements of small single crystals. The most popular sample environment device on SENJU is the 4 K cryostat with a fixed-chi type 2-axes goniometer. We adopted piezo-rotators to rotate the sample crystal under vacuumed and cryo conditions. The 2-axes goniometer works stably even at 4 K and the time for cooling was 4.5 hours. A longitudinal magnet was recently installed on SENJU. The lowest temperature was 1.42 K and the maximum magnetic field was 6.85 T. A test diffraction measurement of a CeCoGe3 single crystal under 1.5 K and 0.5 T showed that Bragg reflections from the sample was clearly observed and the Bragg peaks of the sample crystal were much higher than the peaks from the magnet itself.