Test equipment for verification of crystal linearity at high-flux levels

Abstract

A method and device that provides independent temperature control of x-ray detector crystals, either singly or in small groups. In addition to a thermal control network for the crystals, electronic devices are associated with each detector crystal and are independently cooled using Peltier devices so that lifetime and reliability are maximized. In most operating environments the ambient temperature is less than the operating temperature of the detector crystals. In these situations, the heat removed from the electronics can be used to heat the detector crystals, resulting in efficient operation.

Description

FIELD OF THE INVENTION[0001]The present invention relates to x-ray detector crystals and, more particularly, to a method and device that provides independent temperature control of x-ray detector crystals, either singly or in small groups.BACKGROUND OF THE INVENTION[0002]It is well-known that temperature has a significant effect on the performance of pixilated semiconductor and semi-insulator materials used for photon counting in CT machines. In particular, CdTe, CdTe:Cl, CdZnTe, HgI2, and other semi-insulators exhibit poor carrier transport properties so that significant space charge can build within the material during use. This space charge affects the induced signal, resulting in tailing of the spectrum (i.e., spreading of the lower energy tail), spectral broadening, as characterized by FWHM measurements, and spectral shifts. The counter can become highly non-linear and, in extreme cases, even cease to function.[0003]At low flux, space charge has very little effect. In certain m...

AI Technical Summary

Benefits of technology

[0016]Leakage current, which creates noise in the detector network, is not critically important in this application because spectral integration reduces its impact. As a result crystals can be operated at temperatures much higher than currently practiced or rated and, for a given photon flux, the space charge is reduced.

[0019]In addition to the thermal control network for the crystals, the electronic devices associated with each detector crystal are independently cooled using a second set of Peltier devices so that lifetime and reliability are maximized. These Peltier devices pump heat from the electronics into the outer housing. In most operating environments the ambient temperature is less than the operating temperature of the detector crystals, so heat removed from the electronics can be used to heat the detector crystals, resulting in efficient operation.

Problems solved by technology

Leakage current, which creates noise in the detector network, is not critically important in this application because spectral integration reduces its impact.

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