CALCULATED AND MEASURED PERFORMANCE OF AN X-RAY WIGGLER BEAMLINE AT DORIS-III

The new BW1 beamline at the DORIS III storage ring at HASYLAB in Hambu rg was characterized using ray tracing and finite element analysis pro grams. The angular distribution of the beam, power densities at differ ent locations and spectral distributions were calculated. The main asp ect for the calculations was the thermal deformation of the optical el ements, especially the distortion of the first monochromator crystal r esulting from the high power emitted by the wiggler. In the present se tup a 4 m long X-ray wiggler is used as the source, imposing a heat lo ad of up to 2.5 kW on a directly cooled Si(111) crystal. The bending o f this crystal was analyzed by means of X-ray diffractometry. The expe rimental results were in good agreement with theoretical calculations and reveal the basic characteristics of the directly cooled crystal. T he present limitations of the design indicate ways for optimization wh ich are clearly needed for the available high powers.