The PGT Duo Detector is a novel approach to simultaneous high-resolution gamma spectroscopy in two energy regimes, e.g., at 100-450 keV and 600-1000 keV. The Duo is
two HPGe detector crystals, separated by a lead absorber disk, mounted on a single axis and enclosed in the same cryostat.
The front crystal is an
IGP crystal, which has inherently high resolution at the lower energy regions. The second
detector is an NIGC with excellent resolution for higher energy photons. When a mixed gamma source reaches the endcap, the low energy photons are absorbed within the planar segment. Most of the high-energy gammas pass through to the coaxial detector. The intermediate energy photons, including remnants of some photons scattered within the planar, are absorbed by the lead disk and not counted. |
In this way, two spectra are generated simultaneously. That from the planar has low background and excellent MDA because there is less Compton scattering of high energy photons within that crystal.
The spectrum from the coaxial crystal also has a lower background because clutter from the low and intermediate energy photons has been eliminated. Again, MDAs are improved.
Because the spectra are generated simultaneously, the acquisition conditions are virtually identical and the spectra may be added for better counting statistics. This is a plus for quantitative analysis.
The planar crystal can be selected to cover a greater energy range or to collect photons more efficiently from a distributed source. The lead disk can also be made thinner if intermediate energy photons are of interest. |
The compact design of the Duo makes it suitable for a variety of cryostats, including the portable MPS system for field deployment applications. The simplified electronics can be readily incorporated into a portable PC.
The Duo detector is recommended for measurement of Pu and Am isotopes in fuel fabrication facilities, for non-destructive assay of spent nuclear materials, and for personnel dose reduction Measurements. |
Above are typical spectra obtained with the Duo at count rates above 50,000 cps. The top one is the output of the planar detector with its excellent low-energy resolution. The lower spectrum, from the coaxial detector, also exhibits good resolution and MDAs.
Why use two detectors for two separate runs when one will do the job better? |
