PLANE-GRATING MONOCHROMATOR BEAMLINE FOR THE PTB UNDULATORS AT BESSY-II

At the BESSY II storage ring, the Physikalisch-Technische Bundesanstal t (PTB) will operate insertion devices dedicated to radiometric use. O ne branch of the appendant beamline system will be equipped with a gra zing-incidence monochromator, described here. The monochromator concep t is based on a plane grating operated in parallel light; therefore ex act focusing is maintained for all photon energies irrespective of the angular setting at the grating. The monochromator has been optimized for smalt higher-order transmittance and high power throughput, as req uired by radiometric applications in the wide photon energy range from 20 eV to 1900 eV.