DIAMOND SINGLE-CRYSTALS - THE ULTIMATE MONOCHROMATOR MATERIAL FOR HIGH-POWER X-RAY-BEAMS

A review of the performance of diamond single crystals as a high heat load optical component for synchrotron x rays is given. It has been pr oven experimentally that the bandpass and the angular divergence of th e monochromatic beam provided by a relatively thin diamond crystal use d in an undulator beam are not degraded by thermal effects for a total power up to 280 W (8.7 W absorbed) at a heat flux up to 3.5 kW/mm(2) (109 W/mm(2) absorbed). These high heat load tests and model calculati ons have shown that edge-cooled diamond crystals at room temperature p rovide an easy and widely satisfactory solution to the heat load probl ems generated by undulator beams that are currently foreseen at the th ird-generation storage rings of the European Synchrotron Radiation Fac ility, the Advanced Photon Source, and the SPring-8 facilities. For th is cooling geometry, diamond single crystals offer the additional adva ntage that beam multiplexing can be used. Currently available syntheti c diamond crystals are sufficiently big for undulator beams and their crystalline perfection is adequate. Most of the crystals actually in u se were prepared with their big surfaces (about 30 mm(2) in size) orie nted parallel to the (100) netplanes, but more recently bigger samples whose surfaces are parallel to the (111) lattice planes were obtained . Thus, diamond single crystals are superior to all other monochromato r materials for undulators and for cases where a loss of a factor of 2 in flux combined with a similar gain in resolution (as compared to si licon) are compatible with the experiments.