Speaker
Description
The CEBAF injector, which generates continuous-wave spin-polarized electron beams for nuclear physics experiments at Jefferson Lab, has been upgraded with a polarized 200 keV photoemission electron source (photogun). We present the workflow involved in the development of this photogun with particular emphasis on the transverse match of the beam to the injector. Competing factors arise when optimizing electrode geometries for field-emission-free operation at a predetermined bias voltage, and matching the beam envelope to a pre-determined injector layout. As such an optimization is prohibitively complex when starting out with full 3D models of both the photogun and the subsequent injector, the challenge lies in choosing an adequate level of simplification of all components to capture all significant details. We discuss a systematic process involving particle tracking simulations verifiable with pencil-beam measurements for predicting the beam-optical properties of a given electrode geometry in order to optimize it for a desired set of beam parameters.
