This grant supports development of a portable x-ray energy spectrometer consisting of a cryogenic cooler and hyperpure Si detector. The cooling unit weighs less than 10 kg complete with a one week supply of cryogen, is self regulating in cryogen consumption to provide rapid cool down or response to transient demands while maintaining minimum consumption during steady state operation, requires no electrical power, and has no critical moving parts which could pose reliability or maintenance problems. The liquid carbon dioxide used for the expansion cycle can provide an operating temperature below minus 75 Celsius and should have an essentially infinite shelf life. The project will concentrate on improving the design of the cooler, development of a hyperpure Si detector, and development of a complete detector/cooler prototype portable x-ray spectrometer. It is expected that this development will open the door to a large market for a new generation of highly portable, rugged, and economical low noise x-ray, nuclear, optical, and infrared detector systems which can be stored indefinitely and then restarted quickly.
