Abstract: In the reference radiation field of fluorescence X ray, intensity and purity of X ray are influenced by mechanical equipment, thickness of radiator, thickness of secondary filter, tube voltage of X ray machine. Based on the optimized structural design of reference radiation device, through theoretical analysis calculation and Monte Carlo simulation, differences of fluorescence intensity and purity following the thickness of radiator and secondary filter were obtained, and fluorescence intensity and purity influenced by X ray tube voltage were also got measured. The results show that: to the F-Cs radiation quality, when the thickness of radiator is greater than 490 μm, intensity is saturated. When the thickness of secondary filter equals to 327 μm, purity is the highest. Intensity increases with the rise of voltage, but purity declines with the increase of voltage.

Key words: fluorescence X ray, reference radiation, radiator, secondary filter, tube voltage, MCNP