How to Design a Fiber-Diffraction Experiment

You need to know the first order resolution needed and the highest resolution needed in order to have interpretable data for your system. Then the task is to select a camera length and a size that allows both of these to be achieved. To make this simple, please use our X-Ray Tools Q Calculator.

Enter the X-ray energy in KeV and a trial camera length in mm. Knowing the dimensions of the backstop and the detector active area, one can find the optimal camera length for your application by adjusting it in the application by trial and error.

The following detectors are available at the beamline:

  • The Pilatus 3 1M detector has approximately 1k x 1k 172 µm pixels (169 x 179 mm active area) and can be read out at 500fps.
  • The Pilatus 100k detector has 497 x 195 172 µm pixels (83.8 x 33.5 mm active area) and can be read out at 200 fps
  • The MAR165 CCD detector* has a circular active area 165 mm in diameter with pixels just under 80 microns square (2x2 binned). Can also be used unbinned for 4k x 4k 40 micron pixels.

For small angle fiber diffraction experiments, the available range of camera lengths go from approximately 1 to 5m with 2-3 m being the most commonly used length. The minimum beamstop size that is practical to use with the standard small-angle camera is 3.2 mm.

Available equipment for muscle diffraction include a horizontal X-ray diffraction/laser diffraction/muscle mechanics rig as well as small sample cells allowing rapid sample changing with sarcomere length set by video microscopy. Please contact Thomas Irving or Weikang Ma to discuss your needs for muscle experiments. A short introduction to the basis of the equatorial X-ray diffraction pattern from muscle can be found here: Equatorial Diffraction Intro.

BioCAT Microdiffraction capabilities are described in Barrea, et al. X-ray micro-diffraction studies on biological samples at the BioCAT Beamline 18-ID at the Advanced Photon Source. J. Synchrotron Radiat. 2014 Sept;21:1200-5.

Please contact Weikang Ma to discuss use of this instrument.

Experimenters are encouraged to contact Thomas Irving or Weikang Ma for muscle diffraction questions; or Joseph Orgel with any questions regarding general fiber diffraction. We are capable of accommodating a very wide variety of sample chambers, laser setups, etc.