31a Novel Manufacturing Process for Low-Cost, High-QE Photocathodes

Large area high-performance photodetectors are sought for future high energy physics (HEP) experiments in order to enhance the detection probability of extremely rare events. The photocathode is a key element that determines the performance of the detector. Cathodes with high quantum efficiency (QE), large and uniform photosensitive area, UV-visible sensitivity, cryogenic compatibility, and low radioactivity are of particular interest for neutrino and dark matter detection. Reliable manufacturability of such high-performance cathodes will dramatically advance the science reach for the planned neutrino and dark matter experiments. RMD has a disruptive new method to grow alkali antimonide photocathodes via thermal evaporation of pre-synthesized compounds instead of the traditional sequential evaporation method. The proposed growth method is both fast and less complex and has numerous advantages over the traditional method for growing cathodes towards a high QE and a uniform large area response. The proposed research will benefit significantly from RMD’s previous expertise in solid synthesis, which is one of the key innovations for the projected success. Research will focus on bulk preparation of compounds using impurity-free and radio-pure raw elements and the subsequent thermal vapor deposition of the stoichiometric photocathode thin film across large areas. The goal of the proposed Phase I is to demonstrate feasibility of developing high performance photocathodes using thermal evaporation technique. During Phase I, we will (1) produce the stoichiometric bulk photocathode compounds, (2) develop strategies to evaporate the compounds into high-performance, large-area crystalline photocathodes, and (3) integrate the photocathodes with MCP detectors to carry out QE mapping and UV response. Our ability to produce stoichiometric photocathodes with enhanced performance will demonstrate the efficacy of our approach for creating large area photodetectors with as yet unattained performance.The technology will enable cost-effective photocathode deposition over large areas, and will be the enabling technology for the realization of highly efficient, cost-competitive new detectors for key science drivers in particle physics such as the search for dark matter and the studies of the nature of neutrinos. Availability of such detectors with VUV sensitivity and improved timing and position performance will not only have a profound impact on particle physics but will also have a transformational impact on critical fields including medical imaging through advances in positron emission tomography (PET) detectors, and nuclear detection for homeland security applications.