Thermo Electron Scientific Instruments Corporation

Dean A Stocker

James V Howard

William E Drummond

Mark E Misenheimer

David R Fahrbach

Patrick Paul Camus

Kevin K Kim

James Ronald Hyatt

Gregory S Fritz

Thomas B Jacobs

Dale Anders Wade

In an energy dispersive spectrometer wherein event (particle/photon) detection is performed by counting events spaced by greater than a shaping time, events which are spaced by less than the shaping time are also collected and counted. These 'combined events' are treated similarly to 'single events' which are spaced by greater than the shaping time, and can be used to generate combined-event spectra for comparison and/or use with the conventional single-event spectra. The combined-event spectra can be compared to the single-event spectra to provide an indication of data quality; can be subtracted from the single-event spectra to remove artifacts, and/or can be deconvolved into a single-event spectrum to increase the resolution of the single-event spectrum.

Processing of spectrometer pile-up events

An X-ray detector using a semiconductor detector, most preferably a Silicon Drift Detector, utilizes a field effect transistor or other voltage-controlled resistance to generate an output voltage proportional to its input charge (which is generated by the X-ray photons incident on the semiconductor detector). To keep the charge (and thus the output voltage) to an acceptable range&#x2014;one wherein the relationship between output voltage and input charge is substantially proportional&#x2014;a feedback circuit is provided between the output and input terminals, wherein the charge on the input terminal is depleted when the output voltage begins leaving the desired range. Preferably, this is done by a comparator which monitors the output voltage, and provides a reset signal to the input terminal when it begins moving out of range. Alternatively or additionally, the reset signal may be a pulse supplied to the input terminal from a pulse generator activated by the comparator.

Feedback circuit for output control in a semiconductor X-ray detector

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Fitchburg, WI, United States of America

Dean A Stocker