NIST XCOM and FFAST. Alternate cold x-ray opacity tables with slightly different details.
https://physics.nist.gov/PhysRefData/Xcom/html/xcom1.html
https://physics.nist.gov/PhysRefData/FFast/html/form.html
NIST x-ray transitions database.
https://www.nist.gov/pml/x-ray-transition-energies-database
NIST stopping and range tables (p, e-, alpha).
https://www.nist.gov/pml/stopping-power-range-tables-electrons-protons-and-helium-ions