High-rate germanium gamma spectroscopy: A sensitivity study

Many applications require the generation of gamma spectra at event rates in excess of 10
⁶
s
⁻¹
as well as very good energy resolution, e.g., safeguards, emergency response, and nondestructive assay. Good energy resolution is especially important when lower activity isotopes are sought among a large background (or foreground) that would otherwise dominate the spectrum, such as the minor actinides present in spent fuel after a long cool down time. To this end, we anticipate that high-energy-resolution detectors, such as high-purity germanium, can be adapted to high rates at a small cost to energy resolution, rather than starting with a detector with high-rate capability and medium energy resolution, e.g., LaBr
3
. Here, we present recent design improvements of the ultra high-rate germanium (UHRGe) detection system to allow for a 24-channel spectrum generation output. Further, we present a sensitivity study to determine how uncertainties in parameters of the detection system response affect the resulting spectra. A preamplifier simulator is developed that can emulate the output of the system at various event rates, including very high rates in excess of 10
⁶
s
⁻¹
. Here, we show how various levels of uncertainty in the DC offset of the preamplifier output can affect the full width at half max (FWHM) of the resulting spectrum.