Current status of IBARAKI Biological diffractometer in J-PARC - Optimization of design parameters

Quantum Beam Science Directorate (QuBS), Japan Atomic Energy Agency (JAEA)* Department of Biomolecular Functional Engineering, Ibaraki University, Japan** Institute of Applied Beam Science, Ibaraki University, Japan*** Department of Chemistry and Materials Science, Tokyo institute of technology, Japan**** Department of planning, Ibaraki prefectural government, Japan*****
â—‹Katsuhiro Kusaka* Takashi Ohhara* Ichiro Tanaka** Nobuo Niimura*** Kazuo Kurihara* Takaaki Hosoya* Tomoji Ozeki**** Kazuya Aizawa* Yukio Morii* Masatoshi Arai* Makoto Hayashi***** Kazuhiro Ebata***** Yoshiki Takano*****

Ibaraki prefectural government in Japan has started to construct the TOF neutron biological diffractometer for industrial use at BL03, Materials and Life science facility, J-PARC. The diffractometer is designed so that it can measure sample crystals with maximum cell dimension of 135 angstrom. It is necessary to achieve the efficiency which is more than 50 times larger than the present high performance diffractometer BIX-4 (JRR-3, JAEA, Japan) in order to pioneer a new basic life science fields as well as applied industries.
To realize this performance, the diffractometer will be installed on a coupled moderator has more intense peak and integrated intensity but wider pulse shape than a decoupled one. It is expected that some neighbor Bragg spots will overlap partially each other along the time axis. The overlapping of Bragg spots should be considered for the determination of optic parameters and it is necessary to de-convolute the overlapped spots with faster algorithm and higher accuracy. The three original simulation programs of TOF diffraction data with designed parameters of the diffractometer were developed to obtain information of spot-overlapping, completeness of Bragg spots and spot profiles along the time axis. The consideration of important designed parameters (divergence of incident neutron beam at a sample position, the distance between sample and detector surface and the detector arrangement) focused on biological macromolecular and the strategy of de-convoluting overlapped spots will be reported based on the simulation results by using the programs mentioned as above.