Electron spectroscopy with a diamond detector

An electronic grade single crystal chemical vapour deposition diamond was investigated as a prototype high temperature spectroscopic electron (β^- particle) detector for future space science instruments. The diamond detector was coupled to a custom-built charge-sensitive preamplifier of low noise. A ⁶³Ni radioisotope source (endpoint energy 66 keV) was used to provide a spectrum of β^- particles incident on the detector. The operating temperature of the detector/preamplifier assembly was controlled to allow its performance to be investigated between +100 °C and -20 °C, in 20 °C steps. Monte Carlo modelling was used to: a) calculate the β^- particle spectrum incident on the detector; b) calculate the fraction of β^- particle energy deposited into the detector; and c) predict the β^- particle spectrum accumulated by the instrument. Comparison between the model and experimental data suggested that there was a 4.5 μm thick recombination region at the front of the detector. The spectrometer was demonstrated to be fully operable at temperatures, T, -20 °C ≤ T ≤ 80 °C; the results suggested that some form of polarisation phenomenon occurred in the detector at > 80 °C. This article presents the first report of an energy calibrated (≲ 50 keV) spectroscopic β^- particle diamond detector.