The NIST XCOM Photon Cross Sections Database is considered the reference for obtaining the Mass Attenuation Coefficients for several compounds or mixtures at energies between 1 keV and 100 GeV.
This software provides an alternative to WinXCOM, with a very friendly interface that queries the NIST database in order to obtain the Mass Attenuation Coefficients for Coherent and Incoherent scattering, Photo electric absorption and Pair Production.
The program keeps a relational record of the results and graphs for all your mixtures / compounds of interest. These results are automatically stored in e.g. CSV, HTML and XLS files that can be employed for further processing.