Beamline Description

In order to fulfill the required flexibility in terms of beam characteristics at the experiment, ranging from spot focus to line focus and to parallel beam, the optics of the line consist of two mirrors and the monochromator: a first Pt-coated cylindrical mirror collimates the beam on the horizontally focusing Si (111) double crystal monochomator in 1:1 configuration. The second - vertical focusing - platinum coated mirror is flat and bendable, with a radius adjustable from 6 km to flat.

The double crystal monochromator (DCM) consists of two Si crystals (active area 50×50 mm2, manufactured cut along the [111] direction, which can be precisely positioned and oriented in the X-ray beam. Two successive Bragg reflections with an inherent energy resolution of 0.014% (given by the Darwin angular width of the Si 111 reflection) will direct photons of the desired energy parallel to the incoming beam direction, but offset upward (out of the direct Bremsstrahlung beam). This "fixed exit" operation is achieved by placing the crystals on two independent rotation stages, and translating crystal 2 along the beam direction. The second crystal provides sagittal focusing; it is a ribbed crystal, cylindrically bent to a variable curvature radius.

OPtical schem MCX beamline

Fig.1 - Schematic of the Materials Science Beamline optical system, showing, from left to right, the first (vertical collimating) mirror, the first (flat) crystal, the second (horizontal focusing) crystal and the second (vertical focusing) mirror.

The MCX beamline has two endstations. 

Last Updated on Thursday, 04 August 2022 15:41