A photon counting imaging detector for UV space missions

Abstract

We present the status of our imaging and photon counting UV-MCP detector versions, sensitive in the ultraviolet wavelength range. The detectors have a spatial resolution of 2k pixels per axis, are photon counting, have no readout noise and a very low dark rate, making it ideal for photometry and spectroscopy. The detector can be easily adapted to the requirements of different missions, e.g., only the mechanical interfaces and an electrical interface must be defined to integrate the detector, it is relatively lightweight (3 kg) and has a power consumption of only 15 W. For the sealed version of the detector, we are currently testing a sealed detector head with a cesium telluride photocathode in semitransparent mode. The open version of the detector uses a lightweight door mechanism and is currently optimized to use a KBr photocathode. Interesting advances have been made for AlGaN on MgF2 and MgO substrates. A complete h-GaN film could be grown on MgO (0 0 1), and a complete c-GaN film on MgO (1 1 0). Good crystal quality is crucial to obtain a high QE AlGaN photocathode. Finally, the challenges towards a sealed detector head with a diameter of about 8 cm are described. By rotating the detector window on the detector head during the sealing process, we were able to seal the detector. The photocathode in the sealed MCP detector is stable for at least weeks.