The precise measurement of isotopic ratios required in Safeguards and non-destructive assay (NDA) applications places a severe demand on the techniques of gamma-ray and x-ray spectroscopy. The choice of energy region(s) for analysis depends specifically on the sample type and origin and the material matrix.
National laboratory software codes written to obtain highly accurate isotopic ratios, must deal with these spectra to analyze low-energy and/or high-energy regions in which groups of peaks are located close together. Each code requires exceptional system resolution and stability in order to achieve accurate unfolding of these regions.
Recent safeguards development trends have led to a growing requirement of isotopic ratio determinations involving higher energy gamma-rays. Such needs spring from the need to measure attenuated samples, such as those found in waste assay and in certain homeland security applications. Software codes such as FRAM and MGAHI can now determine Pu isotopic ratios from the higher energy regions of the spectrum. As a consequence, it is desirable to produce HPGe detectors that offer improved higher energy performance, while maintaining the excellent resolution characteristics required in such applications.
The ORTEC Safeguards series include both coaxial and planar geometry detectors, specifically designed to meet the demands of the applications software used for isotopic ratio determination, have been developed to strike an optimum balance between low-energy resolution and high-energy efficiency.
SGD series detectors are compatible with ALL conventional MCA types, although optimum performance will be obtained when used with the ORTEC
Digital Signal Processing Spectrometers.
All SGD detectors feature the following:
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Choice of fixed, portable, and custom cryostats, including the latest MOD multi-orientation dewar option.
- Robust aluminum end-cap
- Streamline preamplifier assembly
- LN2-Free option
The latest low-power resistive feedback preamplifier with "no ring" output, suitable for use with all existing types of MCA systems. Power consumption less than 25 mA at ±12 and ±24 V.
Application Considerations
For samples in thick walled containers, or when significant matrix attenuation is present, it may be necessary to use a higher energy region of the spectrum to perform the analysis. In these cases, the SGD-GEM detectors, which are coaxial or semi-coaxial, have been developed to strike an optimum balance between low-energy resolution and high-energy efficiency.
The SGD-GEM-5050P4 is the "traditional" coaxial detector for use with FRAM in a wide variety of cases, including the measurement of UF
6 cylinders.
The SGD-GEM-5030P4 has a semi-planar geometry and can be used as a more practical substitute for "telescope" detectors which have traditionally been used with the codes TRIFID and MGA in so-called "two-detector" mode. Recent improvements in crystal and preamplifier technologies have made it possible to gather both high- and low-energy spectra SIMULTANEOUSLY with a single SGD-GEM-5030P4 detector.
The SGD-GEM-6560P4 has been produced specifically to provide a large-area detector, which meets the resolution requirements of the FRAM code, and has good high-energy efficiency and a large detection area.