Large High Purity Germanium Well Detector for Biomedical Application

Cardiovascular research uses the microsphere technique as a tool to measure regional blood flow. Although the technique is extremely powerful, the instruments used to assay the microspheres limit the number of different tracers that can be used in one animal to 5 or 6. As is often the case, many more measurements per animal are needed, and the limitation necessitates using many more animals per experiment. This in turn increases costs and decreases the quality of the data, since no animal is its own control for the full set of experiments. A large germanium well counter designed for microsphere work has been evaluated. The detector is 9.8cm long, 5.7cm in diameter, with a 2.1cm well bore. The useable well has a 1.5cm diameter and reaches to within 2cm from the far end of the detector. Energy resolution ranges from 3 keV FWHM at 100 keV to 5 keV FWHM at 500 keV. Detector performance matches well that predicted from Monte Carlo calculations. The counter will increase the research utility of the microsphere technique in a cost-effective manner.