Novel Materials Synthesis and Large Area Manufacturing of High QE Photocathodes

High-performance photodetectors with large areas are sought for particle physics experiments in order to enhance the detection probability of extremely rare events. The performance of the detector is often dictated by its photocathode characteristics. 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. Manufacturability of such high-performance cathodes will dramatically advance the science reach for the planned neutrino and dark matter experiments. RMD proposes to manufacture advanced photocathodes by thermal evaporation using the low-cost proprietary pre-synthesized compounds. The thermodynamic phase diagrams for relevant material system demonstrate a stable phase that is conducive for thermal evaporation. The evaporated cathodes will be evaluated over large areas, for UV-visible sensitivity, fast response and high-QE. The proposed research will benefit significantly from RMD’s 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 evaporation technique. During Phase I, we will produce the stoichiometric bulk photocathode compoundsdevelop strategies to evaporate the compounds into high-performance, large-area crystalline photocathodes, and 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.