Incomplete charge collection

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Manganese resolution
Low energy resolution
Fluorine resolution
Incomplete charge collection
Carbon resolution
Fe55 source
Changes with time
Geometry
Summary

What makes a good detector?

If all the electron-hole pairs generated by an X-ray are not swept to the electrical contacts, the charge signal measured by the FET will be lower than expected, and the energy measured lower than the energy of the incident X-ray. This phenomenon is known as incomplete charge collection (ICC), and results in counts appearing in the spectrum at lower energies than the energy of the X-ray which they represent, typically as a tail on the low energy side of the peak. All detectors suffer from incomplete charge collection to some extent. Low energy X-rays have a very shallow depth of penetration and ICC is usually poor near the front contact. The peak for a low energy X-ray will therefore be broader and have a mean energy lower than expected, due to varying levels of charge collection as each X-ray is measured (Fig. 9). Thus, incomplete charge collection results in detectors with resolutions measured at low energy that are worse than those predicted by theory. In extreme cases it can be the dominant factor controlling resolution at these very low energies (Fig. 9).

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