A detector technology investigation for the Exoplanet Characterisation Observatory (EChO)

The Exoplanet Characterisation Observatory (EChO) is currently being studied by ESA as a medium class mission to be launched in the third decade of the new millennium. EChO requires exquisite detector sensitivity and stability under low-background conditions. The EChO longest wavelength instrument covers the very long wavelength (VLWIR) spectral band from 10 to 16 mu m and HgCdTe (MCT) photoconductors constitute a promising technology. Currently available MCT detectors have been developed for high-background and high-temperature operations and little is known about the performance achievable when the same detectors are operated at cryogenic temperatures, between 77K and 4 K. Here we report on the optical and dark measurements obtained on VLWIR MCT photoconductors from European manufacturers at cryogenic temperatures.