ADAPTIVE INDIRECTLY COOLED MONOCHROMATOR CRYSTALS AT HASYLAB

The high-heat-load monochromator, based on the HASYLAB (Hamburger Sync hrotronstrahlungslabor) 'Torii' design, has been used successfully for 2 years at the BW2 wiggler beamline. The bowing of the reflecting sur face induced by the heat load and water pressure is compensated mechan ically. This is achieved by mounting the specially shaped crystal in a bending mechanism and by heat transfer from the directly water-cooled crystal. We present the latest step in the development of this design . The piezoceramic-driven actuators are replaced by actuators based on the thermal expansion of copper rods. The direct water cooling of the crystal is replaced by a safer indirect water-cooling scheme. Charact erization results of the crystal are presented. The Si(lll) rocking-cu rve width at 9.5 keV was measured to be 8.3 arcsec under 500 W heat lo ad.