Novel Compact Hard X-Ray Spectrometer With Mcps Counting Rate Capabilities For Runaway Electron Measurements On Diii-D

A novel compact spectrometer optimized for the measurement of hard x rays generated by runaway electrons is presented. The detector is designed to be installed in the fan-shaped collimator of the gamma-ray imager diagnostic at the DIII-D tokamak. The spectrometer is based on a 1 x 1 cm(2) cerium doped yttrium aluminum perovskite scintillator crystal coupled with a silicon photomultiplier. The detector dynamic energy range is in excess of 10 MeV, with an energy resolution of similar to 10% at 661.7 keV. The fast detector signal (approximate to 70 ns full width at half maximum) allows for operation at counting rates in excess of 1 MCps. The gain stability of the system can be monitored in real time using a light-emitting diode embedded in the instrument. The detector is expected to be deployed in the forthcoming DIII-D runaway electron experimental campaign.