X-rays and Optics

• U18 cryoundulator, 6 mm minimum gap, accessible at odd  harmonics of ~11n keV
• Cinel double-crystal (fixed exit) Si111 and Si311
• MOCO-feedback ensures long-term position stability
• 0.5 mm x 0.5 mm (typical) collimated beam size
• LVP is at ~63m from the source
• 2 stage CRL focusing for variable beam size to 20 micron

For the experiments at ID06 involving LVP, a prototype U18 cryoundulator upstream in the straight-section with principal harmonic at 11 keV is mainly used. The beamline was also fitted, originally, with an Oxford Diffraction (of DESY) and a Cinel double-crystal monochromator, equipped with both Si111 and Si311 crystal pairs. These are physically limited to about the equivalent of 56 keV (111) by construction. The remainder of the beamline optics was suited for lower energy studies of, initially, optical elements using the micro-optics test bench (both white beam, optical hutch only, and monochromatic, MOTB, EH1) and for higher resolution diffraction and spectroscopy under high magnetic field (EH2), see Billette et al. (2004). The only other optical component used is an EH1-located beam-position monitor, which feedbacks, through the monochromator controller (MOCO), to the pitch (or roll, not required at high energy) of the second crystal of the 111 pair, for position regulation. The beam is otherwise steerable through pitch, roll and yaw of the monochromator, which has itself proven to be both a very flexible, reliable and stable device, when used in conjunction with the MOCO.

The LVP is then typically used with the 111 crystal-pair selecting energies of 33 or 55 keV, at the third- or fifth harmonic of  emission generated by the U18 at about 6.05 mm gap. typically, the beam is collimated to anvil gap or 0.5 mm² or 1.0 mm², depending on application. Since EBS, two-stage focusing using CRL lenses can be employed to obtain beam sizes to 0.02 mm.