High performance high-purity germanium (HPGe) coaxial radiation detector for security and non-destructive analysis

The precise isotope ratio measurements required in safety assurance and non-destructive analysis (NDA) applications place stringent demands on gamma-ray and X-ray spectroscopy techniques. The choice of energy region depends on the sample type, source, and material matrix.

National laboratory software codes written to obtain high-precision isotope ratios must be able to process these spectra to analyze low-energy and/or high-energy regions in which groups of peaks are close together. Each code requires system resolution and stability to accurately expand these areas.

Recent security trends have contributed to the growing need for isotope ratio determination, involving higher energy gamma rays. This requires measuring attenuated samples, such as those found in waste analysis and some homeland security applications. Software codes such as FRAM and MGAHI can now determine Pu isotope ratios from higher energy regions of the spectrum. Therefore, it is desirable to produce an HPGe detector that has higher energy performance while maintaining the excellent resolution characteristics required in these applications.

The ORTEC Safeguard range includes coaxial and planar geometry detectors specifically designed to meet the needs of applications in isotope ratiometry, balancing low energy resolution with high energy efficiency.

The SGD series detectors are compatible with all conventional MCA models and gain performance when used with ORTEC digital signal processing spectrometers.

All SGD detectors have the following features:

• Choose from fixed, portable and custom cryostats, including MOD multi-directional dewar option.
• Rugged and durable aluminum end caps
• Compact preamp components
• No LN2 option

Low power resistive feedback preamplifier with "loop-free" output suitable for use with all existing types of MCA systems. Consumption less than 25 mA at ±12 and ±24 V

Application Notes
For samples in thick-walled containers, or when significant matrix attenuation is present, it may be necessary to use higher spectral energy regions for analysis. In these cases, coaxial or semi-coaxial SGD-GEM detectors have been developed to achieve a balance between low energy resolution and high energy efficiency.

SGD-GEM-5050P4 is a "traditional" coaxial detector for FRAM, suitable for various situations, including the measurement of UF6 cylinders.

The SGD-GEM-5030P4 has a half-plane geometry and is a more practical alternative to "telescope" detectors, which typically use TRIFID and MGA codes in the so-called "dual detector" mode. Recent advances in crystal and preamplifier technology have made it possible to collect both high- and low-energy spectra with a single SGD-GEM-5030P4 detector.

SGD-GEM-6560P4 is specially designed to provide large area detectors to meet the resolution requirements of FRAM codes, with good high energy efficiency and large detection area.

SMART-1 option (-SMP)
The SMART-1 option is used to monitor and report on important system functions, as well as save verification codes and report them later. It includes high voltage, so all instruments require no external high voltage power supply. The SMART-1 features a rugged ABS molded plastic housing with molded strain-relief sealed cables securely attached to the detector end cap. This prevents the detector from being seriously damaged by moisture leaking into the high voltage connector. The SMART-1 can be placed anywhere convenient for use without interfering with shields or other mounting hardware.