Optics and shielding of IBARAKI Biological Crystal Diffractometer (BIX) in J-PARC

J-PARCに建設中の茨城県生命物質構造解析装置(BIX)に対する光学系及び遮蔽設計

栗原 和男; 大原 高志   ; 日下 勝弘*; 仁井田 浩二*; 細谷 孝明*; 友寄 克亮*; 新村 信雄*; 田中 伊知朗*

Kurihara, Kazuo; Ohara, Takashi; Kusaka, Katsuhiro*; Niita, Koji*; Hosoya, Takaaki*; Tomoyori, Katsuaki*; Niimura, Nobuo*; Tanaka, Ichiro*

A novel neutron diffractometer for biologically important materials proposed by Ibaraki Prefecture Government in Japan, BIX is currently in the construction stage at J-PARC. The optics of BIX has been optimized by preliminary analytical estimation and the following simulation with McStas program. In this design neutrons from a coupled moderator are guided through a 17 m-long and curved super mirror guide (radius of curvature = 4,300 m) and a 8 m-long and straight super mirror guide. The super mirror guides has tapered shape in part in vertical and horizontal directions and consist of mirrors with a variety of the critical wave number. Finally, neutrons are projected on the 1 mm area at the sample position 40 m far from the moderator with a half-angle divergence of 0.20 deg. On the other hand, PHITS Monte Carlo simulator has been used to design the shielding around the guide and the detector. Using this program the estimation of background at the detector position has been also attempted to optimize slit geometry.