Electron spectroscopy with a diamond detector

Abstract

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 a calibrated low energy (⪅ 50 keV) spectroscopic β− particle diamond detector.