A flash spectrograph for XANES measurements at SPPS / LCLS.

The SPPS and LCLS are next-generation light sources which will produce ultra-short x-ray pulses a few 10’s of femtoseconds long, with large numbers of photons per pulse. These sources will enable new types of x-ray experiments, but will require new approaches to optical instruments. We present here a spectrograph tailored for use with such sources, allowing the small beam cross-section to be spatially dispersed by means of a curved asymmetric Brag reflecting crystal. The design allows for an adjustable energy range by changing the radius of curvature within certain limits. Although inspired by these new sources, the device is also well adapted to conventional synchrotron radiation beamlines. It is significantly more compact than conventional wavelength-dispersive devices, and has resolution advantages. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]