Preliminary results from the {sup 51}Cr neutrino source experiment in GALLEX

The GALLEX collaboration performed a second {sup 51}Cr neutrino source experiment during fall 1995. The full results from this second source experiment will not be available before the end of 1996. Meanwhile, we present a short description and preliminary results in this informal note. The (preliminary) value of the activity obtained form direct measurements has been found equal to (68.7 {+-}0.7) PBq (with 1-sigma error). This value, which is about 10% higher than the activity of the first source, was achieved by optimizing the irradiation conditions in the Silo{acute e} reactor and doing a longer irradiation of the enriched chromium. Preliminary results show that the ratio, R, of the radiochemically determined activity from {sup 71}Ge counting (57.1 {+-} PBq) to the directly measured activity is (0.83 {+-} 0.10). The combined value of R for the two source experiments is (0.92 {+-} 0.08).