https://physics.nist.gov/PhysRefData/XrayMassCoef/tab3.html
https://physics.nist.gov/PhysRefData/XrayMassCoef/tab4.html

For Fuji-I.P. phosphor BaFBr0.85I0.15: 
 * data from https://physics.nist.gov/PhysRefData/Xcom/html/xcom1.html
 * calculated by Paul Antoine DOUISSARD, ESRF
 * density from https://theses.hal.science/tel-04521313v1/file/SONG_PANYI_2023.pdf, p94

For armorphous Se
 * density from https://pubchem.ncbi.nlm.nih.gov/compound/Selenium#section=Solubility