The Low Energy Germanium (LEGe) Detector is in all aspects optimized for performance at low and moderate energies and has specific advantages over conventional planar or coaxial detectors.
The Low Energy Germanium (LEGe) Detector is in all aspects optimized for performance at low and moderate energies and has specific advantages over conventional planar or coaxial detectors. The LEGe detector is fabricated with a thin front and side contact. The rear contact is of less than full area which gives a lower detector capacitance compared to a planar device of similar size. Since preamplifier noise increases with detector capacitance, the LEGe detector affords lower noise and consequently better resolution at low and moderate energies than any other detector geometry. Unlike grooved planar detectors, there is little dead germanium beyond the active region. This, and the fact that the side surface is charge collecting rather than insulating, results in fewer long-rise time pulses with improved count rate performance and peak-to-background ratios.
The LEGe detector is available with active areas from 50 mm2 to 2000 mm2 and with thicknesses ranging from 5 to 20 mm. For applications involving moderate gamma-ray energies, the LEGe detector may well outperform a more expensive large volume coaxial detector. The efficiency curve given below illustrates the performance of a typical LEGe detector.
To take full advantage of the low energy response of this intrinsically thin window detector, LEGe cryostats are usually equipped with a thin (1 to 20 mil) beryllium window. A LEGe cryostat can also be equipped with a 0.6 mm carbon epoxy window which improves ruggedness over the Be window, but still has a good low energy transmission. For applications at energies above 30 keV, the LEGe detector can be provided with a conventional 0.5 mm Aluminum window. In any case, a wide range of available Mirion cryostats allows optimizing the detector configuration for your application.
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