Closed cycle gas cryogenically cooled radiation detector

A method of cryogenically cooling a radiation detector, comprising the steps of:

• (a) providing:
• a closed cycle cryogenic cooler having a high pressure compressed refrigerant supply conduit, an expansion chamber, an flow limiting orifice from said compressed refrigerant supply conduit to said expansion chamber, and a refrigerant return conduit, said closed cycle cryogenic cooler being subject to the generation of vibration during operation;
• a thermally conductive member having a first portion and a second portion, being in thermal and mechanical communication with said closed cycle cryogenic cooler at said first portion, and having a nonunity vibration transmission function from said first portion to said second portion of said thermally conductive member;
• and
• a cryogenic radiation detector, having a sensitivity to radiation and to vibration and an output, mounted in thermal communication with said second portion of said thermally conductive member, said nonunity vibration transmission function modifying vibrations to which said detector is sensitive, to reduce an effect of said vibration on said output;
• (b) providing a compressed refrigerant supply to said supply conduit;
• and
• (c) venting expanded refrigerant from said return refrigerant conduit.

A cryogenic cooling apparatus for a radiation detector, comprising:

• a cryogenic cooler having a vibration of operation, said vibration of operation being of at least a first level;
• an uncompensated detector, having a sensitivity to radiation and to vibration, and an output, which the detector is mounted in thermal communication with said cryogenic cooler, said uncompensated detector producing an unacceptable output resolution when subject to vibration of at least said first level and producing an acceptable output resolution of at worst about 140 eV at 5.9 keV from .sup.55 Fe at 1000 cps with a 40 .mu.S time constant when subject to vibration of at most a second level;
• and
• a vibration compensation system reducing an effect of the vibration on said detector output so that, when said cryogenic cooler produces at least said first level of the vibration, said compensation system produces said acceptable output resolution.

A detector system for measuring an energy of an X-ray, comprising:

• (a) a lithium drifted silicon crystal X-ray detector system having an X-ray sensitivity and a vibration sensitivity, X-rays and vibration each causing a variation in an output current of said x-ray detector system, said x-ray detector system including an electrical amplifier circuit receiving said output current and producing an amplified signal;
• (b) a support for said detector system, said support being coupled to a device subject to a mechanical vibration, said amplified signal of said x-ray detector system amplifier having a vibration-related signal component which, in the absence of compensation, increases a FWHM of said output to an amount greater than about 140 eV at 5.9 kev from .sup.55 Fe at 1000 cps with a 40 .mu.S time constant;
• and
• (c) means for compensating said vibration-related increase in FWHM of said x-ray detector system amplifier to an amount less than or equal to about 137 eV at 5.9 kev from .sup.55 Fe at 1000 cps with a 40 .mu.S time constant.