Simulation and Measurement of Horizontal Emittance via Undulator High Harmonics at the APS-U

Abstract The transition from 3rd to 4th generation synchrotron light sources via Diffraction Limited Storage Rings (DLSRs) is largely de=ined by the reduction of horizontal emittances and, in turn, achieving more uniform transverse X-ray beam pro=iles. Previously at Advanced Photon Source (APS), SPECTRA simulations were performed to compare to the vertical emittance measurements made at the IEX undulator and beamline. The alignment in measurement and simulation drove the desire to measure the horizontal emittance at the APS-Upgrade. Simulations in SPECTRA and ongoing work in Synchrotron Radiation Workshop (SRW) guide our experimental strategy. In the present work, results from SRW will be presented. We will then conclude with commissioning measurements of beam size and emittance in the APS-U as well as a discussion on the advantages to the undulator high harmonics method when compared to other methods at the APS-U.