SAXS Analysis

    Some useful hints how I usually do it in Fit2d

Radially averaging

 

To analyze a scattering pattern from a 3d-powder, like e.g. a non-oriented block copolymer sample, you might want to make a radially average over the data. This can be  done by INTEGRATE from the SAXS/GISAXS menu. You will need the usual things like pixel size (70.7 micron for the Quantum 1, 47.19 micron for the medoptics), sample detector distance, wavelength and beam centre. Here you have an x-axes with physical values.

Masking

This is done best in two ways: At the moment the pixels at the border aren't used, because the beam pipes are a little bit too small. These pixels can be masked by MASK THRESHOLD in the MASK menu of the SAXS/GISAXS menu. The unused pixels lie below a certain threshold and can be masked out in this way. This tool can also be used for masking away pixels larger than 65000 for noisy images. Second I use the MASK POLYGON to cut away the beamstop.

Kratky plots

If you want to plot your data as Iq² against q or do some other special plotting, this can be done under 1D-TRANSFORMS in the SAXS/GISAXS menu. Note: If you already have a logarithmic scale in  the Z-SCALING menu, selecting YES in the TAKE LOG OF I^a*q^b would give you a double logarithm, which is pretty much useless.