Miniature Long-Life Cooler for Portable Gamma Ray Detectors

This proposal describes a battery operated cryocooler to be used for cooling High Purity Germanium (HPGe) detectors, commonly used for the detection of gamma rays. HPGe detectors are highly suitable for identifying nuclear materials, which is of great interest in the Department of Homeland Security (DHS) applications. HPGe detectors need to operate near 110 K requiring refrigeration for portable HPGe detectors. Portability is highly desirable and can be accomplished by means of a standalone, compact, low-vibration, efficient cryocooler. Power consumption is to be sufficiently low so that the overall system including battery packs is indeed portable. Various existing cryogenic refrigeration systems are thought not to be applicable for the current DHS application either for reasons of excessive power consumption, vibration or system mass, or for lacking reliability and efficiency. To address the refrigeration issue, we propose to develop a miniature pulse tube cooler. High frequency, pulsetube coolers (PTCs) represents the most promising technology for achieving lightweight standalone cryocoolers. Applications of this cooler include cooling of infrared and gamma ray detectors, cooling of electronics, and for use in the biomedical industry.