Abstract

ABSTRACT The performance of a commercially available 1-dimensional x-ray detector based on a directly bombarded self-scanned photo-diode array has been evaluated for x-rays in the 6-8 KeV range. The detector consists of a linear array of 1024 pixels, each approximately 25 μm wide by 2000 μm tall. Modifications to allow cooling to -55°C, which is required for long x-ray exposures, are described. The signal yield is 0.63 ADC counts/Fe55 x-ray, resulting in a detective quantum efficiency greater than 0.5 for doses over a range of 10 to 104 x-rays per pixel per scan when operated at -55°C. The resolution is about 3 pixels (75 μm FWHM) and the response with respect to dose is linear up to 1.5 x 104 x-rays integrated per pixel per scan. There is some non-linearity at doses below about 1000 x-rays/pixel/scan. The detector has very little geometric distortion. The uncorrected uniformity of response of the individual pixels (field flatness) is good to about 2%. However, the variation in responsiveness is stable and a field flatness calibration can be readily used to correct the uniformity of response.

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