| 摘要 |
A radiation detector having an evacuated envelope (35), a radiation detector (34) on a cold finger support in the evacuated space, a closed cycle gas cooling system (3, 45) to cool the cold finger to provide cryogenic operation of the radiation detector, and a getter (5, 16) in the evacuated space to maintain an evacuated condition. The evacuated envelope includes a radiation window (25). The radiation detector is preferably an X-ray detector employed in an energy dispersive spectrometry system. The evacuated space is preferably held at a pressure of less than about 1 mTorr to achieve molecular flow of remaining gas molecules, minimizing parasitic heat input. The closed cycle gas cooling system employs compressed refrigerant, which is precooled in a counterflow heat exchanger (103) and allowed to expand in proximity to the cold finger, thus absorbing heat and maintaining cryogenic temperatures. A getter material, preferably activated carbon, is provided to absorb gasses and maintain the low pressure during operation. A vibration effect attenuation system (8) is provided to reduce effect of cooler induced reduction in detector resolution.
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