Development of High Purity Germanium Detectors for High Rate Gamma-Ray Spectroscopy and Imaging
While High Purity Germanium (HPGe) detectors are the gold standard for high-resolution gamma-ray spectroscopy, conventional, coaxial HPGe detectors show significant performance degradation at high incident count rates (tens of thousands of counts per second (cps)). This dissertation describes a new prototype high-purity germanium detector that has good energy resolution and high throughput performance at count rates in excess of 2 Mcps, as well as providing 3D position sensitivity. This device allows for high-resolution spectroscopy and imaging in high count rate environments, which is of interest for many applications in basic and applied nuclear science.
The detector design, which features a double-sided strip detector (DSSD) geometry with a strip pitch of 0.5 mm, was selected by performing detailed analytical and numerical calculations of the expected efficiency, throughput, timing, energy, and position resolution for various geometries and electrode configurations. The design study and the trade-offs considered in selecting the detector geometry will be presented. Details of the design, predicted performance, and ongoing fabrication will be discussed. Whilst the final fabrication of the device has not yet been completed, simulations indicate that this detector will, at an event rate of 2 Mcps, have an energy resolution of less than 2 keV at 662 keV and throughput greater than 90%.