Development of high performance bi-alkali photocathodes for next-generation sensors

Next generation sensors such as microchannel plate based photomultiplier tubes call for robust, low-cost photocathodes with high quantum efficiency and low dark current. Traditional alkali photocathodes grown through a diffusion growth process encounter material challenge and are being investigated using X-ray scattering to optimize their performance. Photocathodes with peak quantum efficiency over 30{\%} at $\sim$ 400 nm wavelength were grown via a newly proposed growth method. A new photocathode growth chamber was built and incorporated into the Argonne photodetector fabrication facility to obtain robust, highly efficiencient bi-alkali photocathodes. The progress on the photocathode study, growth design and experimental results will be reported and discussed.