Brookhaven Lecture

Photocathode guns are critical components of accelerators used for high-energy physics, nuclear physics, and light sources. In the accelerators for particle and nuclear physics, the electron sources deliver bright, highly spin-polarized, high-charge electron beams, which are ultimately employed as probes for physics. At RHIC, scientists use high-quality electron beams to cool the ion bunch in order to maintain high luminosity during long collision stores. In the future EIC, high-intensity polarized electron beams will collide with ions for probing nuclear structures. RHIC and EIC have a big demand for high-quality electron sources. The high Quantum Efficiency (QE) photocathodes, i.e., the actual source material of the electrons, combined with high gradient Continuous Wave (CW) guns are very challenging. Scientists around the world spent decades on research and development of these devices. The presenter developed very robust high quantum efficiency multi-alkali photocathodes at BNL, and eventually used them in the guns, thus successfully supporting the RHIC electron cooling projects.

Meanwhile, the presenter led the novel polarized HVDC photo gun development for EIC R&D. Multiple novel concepts are integrated into this gun design, and finally commissioned the gun beyond the EIC requirements by order of magnitude. In this talk, I will mainly discuss the electron sources which consist of photocathode, and electron gun. I will focus on the photocathode developed for LEReC in the RHIC and the polarized HVDC gun developed for EIC. In the end, I will discuss electron source applications beyond the nuclear program.