The scattering setup was designed with a focus on hierarchical, wood-based materials; for example, the WAXS detector allows monitoring diffraction from cellulose fibrils/fibers in all directions of the scattering plane, which is instrumental for scanning SWAXS mapping of cellulose fibril orientation. Selected technical details are provided below.

Detectors

ForMAX is equipped with two state-of-the-art hybrid pixel detectors: a Dectris EIGER2 X 4M SAXS detector and a custom-designed X-Spectrum Lambda 3M WAXS detector.

DetectorEIGER2 X 4MLambda 3M “windmill”
UsageSAXSWAXS
Number of pixels4M3M
Sensor size (h x v)2068×2162 pixels4x512x1536 pixels
Pixel size (h x v)75×75 µm255×55 µm2
Maximum frame rate500 Hz1 kHz

The SAXS detector is placed on a motorized XYZ trolley inside the SAXS flight tube and can be placed approximately 800 – 7600 mm downstream of the nominal sample position. The figures below show the smallest and largest scattering vector moduli versus x-ray energy for selected sample-to-detector distances (SDD), assuming the x-ray beam impinges in the center of the detector.

Saxs Homepage
Nominal minimum (left) and maximum (right) SAXS q versus x-ray energy for selected sample-to-detector distances.

The WAXS detector is mounted on an evacuated nose cone of the flight tube and the four modules of the WAXS detector have a “windmill” geometry with a hole in the center, to pass through the direct beam and the SAXS signal (see image below). It allows WAXS data collection at scattering angles 2θ=7-20 degrees, in all directions. See table below for details of the detectors.

Waxs Homepage
Left: Cellulose diffraction pattern, measured from a thin piece of oak at 12.7 keV. Right: Nominal accessible WAXS q range (gray area) versus x-ray energy.

Sample manipulation

ForMAX offers a modular 7-axis stack of sample stages from Huber for SWAXS experiments. From bottom to top:

  • 2-circle segment (pitch, roll), model 5203.30 (+/- 13 and +/- 12 degrees range for lower and upper axis, respectively)
  • vertical stage, model 5103.C30 (+/- 10 mm)
  • 2-axis horizontal stage, model 5102.25 (+/- 25 mm translation range for each axis)
  • custom large-range pitch stage, model 5202.80 (+/- 45 degrees)
  • yaw stage, model 408
  • either manual 5-axis goniometer head 1002/1005 optical breadboard (M6 25×25 mm centred hole pattern) can be mounted on top
  • optional PMMA pins for sample mounting (local contact can provide details)