Development of photon detectors for a fast focusing DIRC

We report progress in developing a focusing DIRC with very good timing resolution. This basic detector development has been motivated by a possible upgrade of the very successful BaBar DIRC particle identification detector for a future Super B-factory. We have built a single bar full size prototype, which aims to reduce the chromatic error by precise timing, and to remove the effect of bar thickness with a focusing mirror. This paper describes the design of the prototype, and systematic studies of the timing resolution and position response for single photons for two 64-pixel detectors: (a) Hamamatsu Flat Panel PMTs, and (b) Burle MCP–PMTs. To test the prototype, we have developed new electronics for ∼300 pixels capable of measuring a single electron timing resolution to ∼100 ps. We also report on a first measurement of aging with the MCP–PMT.