A DOUBLE-CRYSTAL MONOCHROMATOR FOR EXAFS MEASUREMENT AT NSRL

A double-crystal monochromator has been constructed for the EXAFS beam line which was radiation from a 6 T single-period superconducting wigg ler at National Synchrotron Radiation Laboratory (NSRL). It utilizes t hree different pairs of crystals mounted on a linkage mechanism as the diffraction elements to cover a wide energy range of 0.9-12.4keV and to provide a spatially fixed monochromatic beam with an optimal energy resolution. The combination of the linkage mechanism and the goniomet er drives the crystals to give fine energy scanning in the neighborhoo d of a specific element absorption edge and enables fast accurate repo sitioning for a given energy. Details of the design and construction o f the monochromator are presented in this paper. (C) 1998 Elsevier Sci ence B.V. All rights reserved.