Micro-Photomultiplier Array

70053S02-II Many nuclear physics experiments supported by the DOE use photomultiplier tubes (PMTs) for the detection of optical signals induced by nuclear particles in detectors. PMTs are the most sensitive light detectors available and are frequently utilized when single-photon and excellent- timing signal detection are necessary. However, hand-assembled PMTs are relatively bulky, expensive vacuum tube devices that haven¿t changed significantly in the last few decades. The miniaturization of photomultipliers, from traditional photocathode sizes of approximately 1 cm diameter down to sub-millimeter sizes, would expand the applicability of this light detection technology for both scientific experimentation and commercial utility. This project will produce sealed and working prototype micro-photomultiplier arrays (MPA). Phase I modeled and optimized the two-dimensional MPA structure, using electric field calculation and electron trajectory mapping software. Batch mode semiconductor processes were developed to fabricate parts with micrometer precision. Microdynode fabrication was accomplished using standard semiconductor process techniques, and a micromachined, fully pixellated dynode structure for producing a micro-photomultiplier array was demonstrated. Phase II will focus on improved manufacturability, improved dynode assembly, the use of higher secondary-electron-yield coatings, photocathode processing compatibility, adding multi-anode readout capability, and final device packaging and testing. Forty prototype sealed micro-photomultiplier arrays will be fabricated. Commercial Applications and Other Benefits as described by awardee: The miniature photomultiplier array should significantly change photomultiplier technology and create new applications in medical and biological diagnostic equipment, and in portable and handheld analytical instrumentation. In addition, photomultiplier technology is a key component of many devices being employed for screening cargo carriers passing through entry ports into the United States. The micro-photomultiplier array should enable higher quality inspection, faster detector response times, and lower overall system costs.