Portable, low-power, mechanically cooled Ge spectrometer

A light-weight portable mechanically cooled γ-ray spectrometer has been constructed and tested. The spectrometer is based on a high-purity n-type Ge coaxial crystal, ∼5 cm long×5 cm diameter, a small, low-power Stirling cycle microcooler, and a low-power custom electronics package. The energy resolution of the spectrometer is ∼3.5 keV at Eγ=662 keV, the power requirements are ∼15 W DC, and the combined weight of the Ge, housing, and controller is approximately 10 pounds. The spectrometer qualifies therefore as “hand held”. It is suitable for field operations, because of its light-weight, low-power draw, and operational lifetime. The microcooler itself has a MTBF >30,000 h, and the spectrometer runs for several months (at least 6) before a 2 day recycle is required.