A space-based application of diamond sensors

Over the past several years at Los Alamos National Laboratory (LANL) we have been evaluating a variety of intrinsic diamond sensors, for potential use as x-ray detectors on satellite platforms. Radiation damage from the charged-particle space environment is a concern for the performance and lifetime of spaceborne instruments, and so diamond is an attractive candidate for such sensors. We have characterised both CVD and natural type-IIa diamond samples, obtained from multiple sources, and all with interdigitated surface electrodes for charge collection. Two LANL beam lines located at the Brookhaven National Laboratory's synchrotron facility provide a source of low energy (up to 6 keV) x rays with which we measure spectral response of the sensors. Additionally, at LANL we operate a laser- plasma generated, pulsed soft x-ray source for further characterisation of the samples over the energy range to a few hundred eV. In one series of tests on natural type IIa diamond, we subjected a sample to multiple large doses of low-energy (100keV) protons - those particles expected to cause the greatest amount of cumulative surface damage on the diamond in a space-based environment. Using both the laser-plasma and synchrotron x-ray sources, we verified that the damage was limited to - I pm, and that the detector retained the majority of its sensitivity to x rays over the available 6 keV energy range. In the near future we will be evaluating some new single-crystal CVD diamond samples recently provided to us by Element Six in the UK.