Experimental characterization of the radiation from insertion devices at third generation synchrotron radiation sources

The experimental characterization of the radiation from the insertion devices was performed at the Advanced Photon Source - third generation synchrotron radiation source. The radiation diagnostics includes absolute spectral flux measurements and measurement of the particle beam emittance. Two experimental methods of absolute flux measurement for insertion devises were employed. A crystal monochromator was used to characterize the undulator radiation. A gas scattering method was applied to characterize radiation from both an elliptical multipole wiggler and undulator. The particle beam emittance determination included particle beam divergence and size measurements. The measured absolute flux was compared to the calculated flux to characterize undulator performance.;The absolute flux measurements of the undulator radiation at the maximum storage ring current showed that the measured undulator flux is in good agreement with the calculated flux. The calculations of the expected undulator radiation were made using the measured undulator magnetic field and with experimentally determined particle beam divergence, size, energy spread, and distance to the source.;The gas scattering method was applied to characterize the performance of the elliptical multipole wiggler which produces circular polarized radiation. The total flux and the degree of the linear polarization were measured. The scattering method has lower energy resolution than the crystal monochromator which limits its application to characterize the undulator radiation. Using a proper convolution of the calculated undulator spectrum with all energy broadening functions it is possible to characterize the undulator performance.