A Double Multilayer Monochromator at an ESRF Undulator for Microbeam Experiments

A water-cooled double W/Si-multilayer monochromator has been operated at an ESRF low-β undulator beam. For a fixed distance of the two multilayers the first-order Bragg reflection was at ~8 keV. The peak power density of the beam at the exit of the multilayers was ~1 W mm⁻² and the flux density of the first order after a 10 μm collimator was 4 × 10⁵ photons s⁻¹ μm⁻² mA^−1. The performance of the beam in microbeam diffraction has been tested on a 20 μm W wire. The observed pseudo-Laue pattern is discussed with respect to the multilayer spectrum.