Miniature, Efficient, Low-Vibration Cryocooler for Gamma Ray Detectors

Hand-held gamma ray spectrometers are a vital tool for detecting and identifying nuclear materials to counter the threat of radiological and nuclear terrorism. The HPGe crystals in these detectors must operate at cryogenic temperatures to achieve good energy resolution. We propose to develop an innovative, miniature cryogenic cooling system that will be ideal for hand-held detectors. High efficiency will enable long battery life, and low vibration will improve the detector sensitivity. In addition, the system will be lightweight and inexpensive to produce. In Phase I, we will prove the feasibility of our approach by building and demonstrating critical components and producing a conceptual design for a prototype cryocooler. In Phase II, we will build and demonstrate a complete prototype system. Homeland security applications include nuclear materials interdiction, safeguards inspection, and emergency response. The cooler can also be used to cool portable x-ray detectors and infrared sensors used in military targeting and guidance systems. The commercial nuclear industry can use the cooler/detector for in-situ waste assay measurements, nuclear reactor maintenance, and health physics.