Reanalysis of the Gallex solar neutrino flux and source experiments

Abstract

After the completion of the gallium solar neutrino experiments at the Laboratori Nazionali del Gran Sasso (Gallex: 1991–1997; GNO: 1998–2003) we have retrospectively updated the Gallex results with the help of new technical data that were impossible to acquire for principle reasons before the completion of the low rate measurement phase (that is, before the end of the GNO solar runs). Subsequent high rate experiments have allowed the calibration of absolute internal counter efficiencies and of an advanced pulse shape analysis for counter background discrimination. The updated overall result for Gallex (only) is 73.4−7.3+7.1SNU. This is 5.3% below the old value of 77.5−7.8+7.5SNU (Gallex Collaboration, W. Hampel et al., 1999 [1]), with a substantially reduced error. A similar reduction is obtained from the reanalysis of the 51Cr neutrino source experiments of 1994/1995.