affect mass determination for larger samples however absorption correction is made in a manner described hereinafter compton scatter cross section as used herein is literally the probability that an x ray incident on a sample will be compton scattered per unit mass of sample for example 100 000 incident x rays per second on irradiating a sample having a compton scatter cross section the equivalent of 1 this means that 1000 of the incident x rays will be compton scattered it is a measure of the probability of the compton scatter occurring rayleigh scattering on the other hand which as indicated above increases proportionately with the square of z atomic number see fig8 from tertian and claisse which shows incoherent and coherent mass scattering coefficients as a function of atomic number for ag k u03b1 radiation and scattering angle of 90 u00b0 this information may be used to correct the mass determination which is based on the assumption that compton scattering cross section is constant the following relation is useful corrected mass is the net mass of the sample to be determined cc is a calibration constant that is determined by measurement samples of known mass in theory this constant depends upon such physical parameters as the type of equipment or apparatus used such as the operating characteristics of the x ray tube 3 and the detector 9 fig3 the location of the.