Oswald Siegmund (Space Sciences Laboratory, U.C. Berkeley), John Vallerga (Space Sciences Laboratory, U.C. Berkeley), Barry Welsh (Space Sciences Laboratory, U.C. Berkeley), Anton Tremsin (Space Sciences Laboratory, U.C. Berkeley), Jason McPhate (Space Sciences Laboratory, U.C. Berkeley)
Keywords:
Abstract:
Recent advances in UV-Visible ground and space borne detectors with the unique ability to record photon X,Y,T high fidelity information include the development of GaN UV photocathodes and cross strip high resolution position encoding readouts. Such sensors have the distinct advantage of being able to record the accurate time of each detected photon event, which is important for time dependent applications in space astronomy, biology, and time of flight instruments. Newly developed GaN photocathodes have achieved up to 80% quantum efficiency at 120 nm and in the opaque mode they demonstrate high efficiency up to a cutoff wavelength of about 360 nm. Meanwhile semitransparent GaN cathodes have achieved ~20% quantum efficiency in the 240 nm to 360 nm regime. Imaging devices with these photocathodes have demonstrated good spatial resolution and uniformity, with relatively low background event rates. For photon counting imaging detectors we have developed cross strip anode readouts with large, high spatial resolution formats capable of high counting rates and extended lifetimes. We have achieved resolutions of < 10 !m in tests over 32 mm x 32 mm anodes with excellent linearity. High-speed electronics for the cross strip readout are currently under development and should achieve > 1 MHz for random photon rates, and we have demonstrated time tagging of events to better than 1ns. A variety of sealed tube detectors are also in development with both GaN and GaAs photocathodes.
Date of Conference: September 16-19, 2008
Track: