Experimental x ray mass attenuation coefficients for materials of low atomic number in the energy range 4 to 25 keV

Experimentally determined mass attenuation coefficients for C 2 H 4 , CO 2 , N 2 , O 2 , CF 4 , Ne, H 2 S, HCl, Ar, air, Mg, Al, SiO 2 , (C 2 H 5 ) 3 PO 4 at a series of energies from 4.508 to 25.192 keV are presented in tabular form, together with estimates of total random and systematic uncertainty. Full details of the experimental method are given. This data set enables deduction of a coherent data set for the elements from Z=6 to Z=18 with better accuracy, internal consistency and reliability than any previously published data in this energy and atomic number range.