March 2013 Archives

Professor Y. Takahashi (Osaka University, Japan) and his colleagues have recently reported that coherent X-ray imaging using Bragg diffraction can aid the observation of nanoscale dislocation strain fields in a silicon single crystal. The experiments were done with 11.8 keV micro-focused X-ray photons, around 1 μm in both directions, using KB mirrors at BL-29XUL, SPring-8, Japan. In this research, a 1 μm thick silicon (100) single crystal was placed in the X-ray path so that X-rays could pass through it and the 220 Bragg reflection spot was observed by a CCD camera 2 m behind the sample. The sample was scanned in XY directions as well. The research team found phase singularities, i.e., two pairs of vortices with opposite directions in the phase map, that corresponded to the locally dark positions in the intensity map. It was concluded that this corresponded to the projection of the {111} dislocation loops. For more information, see the paper, "Bragg x-ray ptychography of a silicon crystal: Visualization of the dislocation strain field and the production of a vortex beam", Y. Takahashi et al., Phys. Rev. B87, 121201(R) (2013).

The construction of Brookhaven's National Synchrotron Light Source II is approaching its final stage. Recently the last of 150 magnet girders was installed in the storage ring. Magnets traveled from across the globe, supplied by ring magnet vendors based in six countries: Buckley Systems Ltd (New Zealand), Budker Institute of Nuclear Physics (Russia), Danfysik (Denmark), Everson Tesla Incorporated (U.S.), Institute of High Energy Physics (China), and Tesla Engineering (U.K.). In the experimental hall, meanwhile, 17 hutches have been delivered and constructed for seven beamlines; CSX1 and CSX2 (two branches of Coherent Soft X-ray Scattering and Polarization), CHX (Coherent Hard X-ray Scattering), IXS (Inelastic X-ray Scattering), HXN (Hard X-ray Nanoprobe), SRX (Submicron Resolution X-ray Spectroscopy) and XPD (X-ray Powder Diffraction). For further information, visit the Web page, http://www.bnl.gov/ps/news/news.php?a=23725

An explanation of the CSX beamline construction can be viewed on You Tube.

http://www.youtube.com/watch?feature=player_embedded&v=rximpW0aR9A