*** Brandes 9505418 This Small Business Innovation Research Phase II project is exploring a low-noise, high-gain dynode useful for incorporation into a low-cost, high-performance photomultiplier tube (PMT). PMTs have unmatched sensitivity for visible or ultraviolet wavelengths. Existing PMTs, however, are inadequate or prohibitively expensive for many applications where sensitivity and gain must be combined with stability and reduced noise requirements. Phase I showed that semiconducting diamond's unique properties could be exploited to create a low-noise, high-gain dynode for PMTs. It was found that unoptimized boron-doped diamond has high secondary electron yields, the electron emission energy is low, the electron energy distribution is small, the yield is unaltered by air exposure, and the lifetime is equivalent to conventional dynodes. Further, semiconducting diamond won't charge unlike some conventional materials. Phase II will optimize the growth of diamond for secondary electron emission applications and clarify the electron transport and emission mechanisms. In collaboration with a PMT manufacturer, this phase of the project will be directed toward design, development and testing of a low-cost, high-performance photomultiplier tube incorporating diamond dynodes. Phase III, activities will focus on scaling up the process to enable volume production of the diamond based photomultiplier tubes. The commercial applications for photomultiplier tubes and other electron multipliers are many, including medical applications and imaging, oil well logging, pollution monitoring, nuclear and high energy physics, and spectroscopy. Availability of low-cost, high-performance, diamond-based PMTs would increase their use in a wide variety of such applications. ***
