Potential diagnostics for the next-generation light sources

There is continued interest in developing a diffraction-limited soft or har d X-ray source. Candidate paths include the storage-ring-based free-electro n laser (FEL) and the linac-based self-amplified spontaneous emission (SASE ) FEL for the two regimes, respectively. As previously discussed, target be am parameters are sigma(x,y) similar to 10 mu m, sigma(x',y') = 1 mu rad, a nd sigma(t) similar to 1 ps (0.1 ps for the linac case). We report the use of few- to sub-angstrom radiation emitted by a 7-GeV beam transitting a 198 -period diagnostics undulator and a bending magnet to characterize the part icle beam. A particle beam divergence as low as sigma(y') = 3.3 mu rad was measured using an X-ray monochromator. Additionally, a particle beam size o f sigma(y) < 45 mu m and a bunch length of sigma(t) = 28 ps with 4-ps resol ution were measured using an X-ray pinhole camera with a unique synchroscan and dual-sweep X-ray streak camera as the detector. The adjustable pinhole aperture was varied by more than a factor of 100 to assess spatial resolut ion and dynamic range issues in the system. These diagnostics demonstration s should scale to next-generation applications. (C) 1999 Published by Elsev ier Science B.V. All rights reserved.