GALLEX status report as of November, 1991

Since 18 months, the radiochemical Gallium-Solar-Neutrino Experiment “GALLEX” is fully operative at the INFN-Gran Sasso Underground Laboratory (LNGS) in Central Italy. Among other things, 41 full scale experiments have been performed since June 1990, establishing the technical aspects of the experiment to be successful in every respect, as designed. The first 28 runs were needed to reduce the amount of disturbing cosmogenic 68Ge activity imported from overground to that level at which any remaining activity is no longer distinguishable from the extremely low counter background level for which the experiment is designed. This milestone was achieved, after a long period of heating the target, in May 1991. Since then, GALLEX monitors solar neutrinos undisturbed, runs B29-B41, so far. At least 10 months of data taking are required to achieve even a prelininary result. For a statistically more meaningful result, the experimental conception calls for 4 years of data taking.