Optics Hutch

The optics hutch can provide monochromatic beam for both the 1st and 2nd experimental hutches. The main optical elements are a double laue (Si 111) monochromator and an X-ray transfocator. Other components include an attenuator system (6 axes of 3 attenuators on each axis) and water-cooled slit systems of two types: one primary slit system for beam definition, and secondary slit systems for beam conditioning.

The optics hutch can be operated in different modes: direct white beam or monochromatic beam with or without focusing. Since the transfocator is chromatic, the focused white beam has a limited band pass (~1%). The band pass for the monochromatic beam is determined by the curvature of the crystals and geometry, giving a rocking width which is approximately constant with energy. The crystal thickness is 2.5 mm with an asymmetric cut of 12.5 degrees.

The monochromatic beam is in the orbital plane of the synchrotron displaced by 10-15 mm horizontally from the undulator white beam and the transfocator focusing is in-line with either the white or monochromatic beam.

The laue-laue monochromator is currently operated with two Si(111) crystals in a Rowlands geometry to preserve the source properties. Scattering is in the horizontal plane to avoid any degradation of the vertical source size. The laue-laue monochromator is described in the article by Baruzzo et al and show here:

The transfocator system allows the beam to be collimated or focused in either of the experimental hutches, giving a beam sizes of around ~7x15 hxv microns in EH1 or ~50x200 microns in EH3. When acting as a collimator for other focusing optics for EH3 the transfocator offers flux increase of several orders of magnitude for a small increase in beam size on the sample.