Free-air chamber correction factors for electron loss, photon scatter, fluorescence and bremsstrahlung

Values for the correction factors for electron loss ke and photon scatter ksc were calculated by Burns [1] using the Monte Carlo code EGS4 [2], for all of the free-air chamber standards in use worldwide at that time. Spectral values were derived for the CCRI reference radiation qualities for lowand medium-energy x radiation [3]. In general, the calculated values were in close agreement with the values used at present by each NMI. The most notable discrepancy was in the values for ksc at the lower-energy qualities, where the calculated values were closer to unity by typically 0.2 %. This was attributed to the lack of inclusion of x-ray fluorescence transport in the standard EGS4 code.