Large Area, High Dynamic Range, Sold State Photomultiplier Array for Cherenkov Calorimetry

The Avalanche Microchannel Photo Diode (AMPD) can be used in detectors for high energy physics research. The AMPD is a multipixel array of micro pixels, joined together on a common silicon substrate and working on a common load. The pixels are decoupled in order to minimize interpixel crosstalk and work as independent high gain photon microcounters. These devices are capable of good pixel-to-pixel uniformity, provide negligible noise, and have a very low contribution from excess noise factors. However, for applications such as tile calorimeters, there are limitations with respect to scintillators and wavelength shifters. These limitations include: (1) nonlinearity of the AMPD signal when the number of photoelectrons/tile is greater than the number of pixels, and (2) high dark counts. To address these shortcomings, this project will develop a nano-AMPD structure, realized in silicon-on-insulator (SOI) complementary metal oxide semiconductor (CMOS) materials. The approach will allow very back-thinned (e.g., 7-micron thick) detectors to be built monolithically with the AMPD elements. The approach also will allow amplifiers, biasing, pulse processing, and time-of-flight circuits to be built directly into the SOI wafer ¿ permitting a large area AMPD array to be realized. The design of the SOI CMOS AMPD arrays will be completed in Phase I, and prototypes will be built. In Phase II, a large area array will be fabricated for use in Cherenkov imaging and time-of-flight calorimetry. Commercial Applications and other Benefits as described by the awardee: In addition to high energy and nuclear physics applications, the technology should be applicable to plasma diagnostics in the solar atmosphere, space-based optical receivers, and high-speed image capture for motion analysis. The latter is used in a wide variety of applications, including vehicle-impact testing; biomechanical research; range, aerospace, and ballistics; and particle-image velocimetry.