Development of cryogenic detectors for GNO

The neutrino capture reaction 71Ga(νe,e−)71Ge and the reverse EC-decay is used by GNO to monitor the flux of solar neutrinos in a routinely operating neutrino observatory. Low temperature detectors (LTDs) offer a better performance concerning efficiency, energy resolution and threshold than the proportional counters that are used now. We report on measurements with a detector setup with absorption in 4 π and counting efficiency near 100%. Activated germanium has been integrated succesfully in the LTD setup by thermal decomposition of GeH4.