The objective of this activity was to develop a novel type of X-ray detector that combines two of the most important detector parameters: a large active area and a good energy resolution. This new 'GDD' detector is of gas-filled type, but its internal structure is similar to the widely-used Silicon Drift Detector.

The team working on the activity achieved the best ever energy resolution measured with any gas-filled detector: 9.8% at 5.9 keV. The detector was operated at a low electric field strength in the ion chamber region without gas amplification, which minimises the effects of detector ageing and enables the production of very long-life detectors. The detector works well even at short shaping time constants down to 0.25 μs which enables very high countrate operation of close to a million counts per second with good gain stability. The detector showed no microphonic effects which enables operation in acoustically noisy and/or vibrational environments. In addition, the GDD detector is inherently tolerant to radiation damage.

The team believes that the GDD detector will find numerous applications in commercial markets and ESA missions because of its competent performance parameters.