T. Hosoya

A new biological neutron diffractometer (iBIX) in J-PARC

The present talk describes novel powerful imaging for X-ray fluorescence (XRF) and X-ray diffraction (XRD). So far, the scanning-type imaging has been widely used in those techniques. Though recent progress in high-spatial-resolution imaging using synchrotrons is significant, there have been a clear limit; because of the step-scan, the imaging requires a long measuring time. In many scientific applications, X-ray imaging that are much more rapid, e.g., capable of high-speed resolution have been demanded. It is possible to do X-ray imaging without performing any scans. Here, the method uses quite a wide beam, which illuminates the whole sample surface in a low-angle-incidence arrangement (0.5~3 deg). The detector used is a CCD camera working at 30 fr./sec, equipped with a collimator inside, and the distance between the sample surface and the detector is set extremely close, in order to enhance both spatial resolution and efficiency. Note that the imaging is done with one shot. In the case of XRF imaging, distinguishing elements are required and, therefore, most of the experiments were performed with monochromatic or quasi-monochromatic X-rays. The procedure for XRD imaging uses a combination of exposure and incident X-ray energy scan (or just tuning). Since the present experiment employs a fixed small-angle incidence and also a fixed diffraction angle of around 90 deg, the diffraction plane here is inclined at about 45 deg from the surface of the specimen. By scanning the energy of the incident X-rays, one obtains a diffraction peak, which corresponds to the lattice spacing. Further instrumental details and many applications will be presented. References [1] K.Sakurai, Spectrochimica Acta B54, 1497 (1999) [2] K.Sakurai and H.Eba, Anal. Chem. 75, 355 (2003)

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

1 a new basic life science fields as well as applied industries. To achieve the performance mentioned as above, the diffractometer will be installed on a coupled moderator which has more intense peak and integrated intensity but wider pulse shape than a decoupled moderator. It is expected that some neighbor Bragg spots will overlap partially each other along the time-axis. The overlapping of Bragg spots along the time-axis should be considered for the optimization of design parameters and It is necessary to deconvolute the overlapped spots in order to obtain a data set that has a quality good enough to identify hydrogen atoms in biological macromolecules. 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 time-axis. The consideration of important designed parameters (divergence of incident neutron beam to a sample crystal, the distance between sample and detector surface and the best detector configuration) focused on biological macromolecular, the strategy of data collection and de-convoluting overlapped spots will be reported based on the results of simulation by using the simulation programs mentioned as above.