Xraytrace documentation

The materials used within the calculation are represented by materials table, which is supplied as a an input file, defined at the same moment as the data are loaded (see the computational domain section).

This file has a simple structure - a set of entries for individual material indices, defining how the system should get the material data. Each row starts by material index (to match the indices in the VTK file or vector file defining the sample geometry). Then, material type is listed (0 for direct definition of n, k, density and attenuation, 99 for use of the xraylib database). For material type equal to 0 the further four values

0 0 1 0 0 0
1 0 0.9999 2 3 4
2 99 Si 0 0
3 99 Cr 0 0

If we use the database material (type = 99), we have two parameters more, that can be used to force the system to use different values of attenuation and density than those calculated from the Xraylib database. This is most usually not needed.

A second option how to override the density of the material is to use the following directive in the main parameter file:

OVERRIDE_XRAYLIB_DENSITY
index value

which uses the supplied density for the particular index, but calculates everything using Xraylib as usual based on this density.