Effect of small radiation divergence on measurements of the source size.

摘要

Third-generation storage rings have small particle beam emittances. The size of the particle beam can be determined from the measured image size of the focused radiation source. Undulators are preferred as radiation sources at third-generation storage rings, the radiation emitted by an undulator has both small size and divergence. The effect of the small beam divergence on determination of the source size is discussed here. The analysis is performed in an approximation of a Gaussian distribution of the radiation intensity. The partial approximation and matrix methods were also used for this derivation. It was found that the effect of the small beam divergence depends on the ratio of the angular acceptance of the source to the divergence of the emitted radiation.