Development of a cryogenic detection concept for GNO

The Gallium-Neutrino-Experiment at GNO measures solar neutrinos radiochemically via the reaction ⁷¹Ga(ν,e)⁷¹Ge. In order to reduce statistical and systematic uncertainties in detecting the decay of ⁷¹Ge to ⁷¹Ga, a favourable way could be the use of high-resolution cryogenic detectors instead of the presently integrated miniaturized proportional counters. After the successful development of a highly efficient 4π-detector, optimization of thermal Ge-deposition and decoupling of deposition and detection, present activity concentrates on low background considerations, enhancement of external and internal shielding of the cryostat and a long-term run with artificially activated ⁷¹Ge to prove the feasibility of ‘cryoGNO’ in our Underground Laboratory in Garching.