Enhanced Efficiency Nanowire Photocathode for Large PMTs

65614 The quantum efficiency of a photocathode limits overall device performance in photomultiplier tubes used in nuclear physics research. This project will develop more efficient photocathodes using nanowire technology. In particular, the production of nanowire photocathodes will be optimized, and the physical mechanisms that control their performance will be identified. In Phase I, gold nanowire photocathodes were successfully engineered and shown to have greater efficiency and extended spectral response compared to traditional planar gold photocathodes. Cesium was shown to greatly enhance the photoresponse. Phase II will improve the techniques developed in Phase I for the production of nanowire photocathodes and engineer nanowire photocathodes from other materials. Theoretical work will be performed in order to understand the mechanisms controlling photoemission from nanowires. Other techniques for the production of nanowires will be explored, and more extensive tests and measurements will be performed to characterize the nanowire photocathodes. Commercial Applications and Other Benefits as described by the awardee: In addition to nuclear physics research, the miniature high-speed photomultipliers should have application in nuclear nonproliferation, optical communications, medical imaging, night vision systems, robotic and machine vision systems, mass spectroscopy, and missile defense systems.