Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
We present a detailed study of the emittances produced in the Cornell Energy Recovery Linac Photoinjector. Both the horizontal and vertical transverse phase spaces, as well as the time-resolved (sliced) horizontal phase space, were simulated and directly measured at the end of the injector for 19 pC and 77 pC bunches at roughly 8 MeV. The resulting 90% normalized transverse emittances for 19 (77) pC/bunch were 0.23 ± 0.02 (0.51 ± 0.04) μm in the horizontal plane, and 0.14 ± 0.01 (0.29 ± 0.02) μm in the vertical plane, respectively. These emittances were measured with a corresponding bunch length of 2.1±0.1 (3.0±0.2) ps, respectively. For both bunch charges, the rms momentum spread was determined to be on the order of 10-3. Excellent overall agreement between measurement and simulation has been demonstrated. The beam brightness measured in this work is significantly better than the best of modern storage rings, and represents a milestone for the field of high-brightness, high-current photoinjectors.
