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(Gallex: -1997 GNO: 1998 GNO: -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 +7.1 −7.3 SNU. This is 5.3% below the old value of 77.5 +7.5 −7.8 SNU [1], with a substantially reduced error. A similar reduction is obtained from the reanalysis of the 51 Cr neutrino source experiments of 1994/1995.

Predictions for neutrinoless double-beta decay in the 3+1 sterile neutrino scenario

“…However, the standard 3ν mixing paradigm has been challenged by indications in favor of short-baseline oscillations generated by a new larger squared-mass difference ∆m 2 SBL ∼ 1 eV 2 : the reactor antineutrino anomaly [6], which is a deficit of the rate ofν e observed in several short-baseline reactor neutrino experiments in comparison with that expected from the latest calculation of the reactor neutrino fluxes [7,8]; the Gallium neutrino anomaly [9][10][11][12][13], consisting in a short-baseline disappearance of ν e measured in the Gallium radioactive source experiments GALLEX [14] and SAGE [15]; the signal of short-baselinē ν µ →ν e oscillations observed in the LSND experiment [16,17]. The simplest extension of 3ν mixing which can describe these short-baseline oscillations taking into account other constraints is the 3+1 mixing scheme [18,19], in which there is an additional massive neutrino at the eV scale and the masses of the three standard neutrinos are much smaller.…”

Possibility of measuring theCPMajorana phases in0νββdecay

“…All existing neutrino oscillation data (with the exception of the LSND [21], MiniBooNE [22], short baseline reactor [23] and Gallium [24]) anomalies) are perfectly described by the minimal scheme of three-neutrino mixing.…”

Interim Design Report

“…Furthermore, energy resolution, background suppression, and systematic uncertainties have been improved. Data from SNO are combined with the global data on solar neutrinos [44][45][46] including updates on Gallium experiments [47,48] as well as results from Borexino [49] on 7 Be neutrinos yielding an improved determination of the atmospheric parameters. The MINOS experiment [50] is searching for ν µ disappearance with a baseline of 735 km.…”

“…where N F D and N N D are the observed far and near detector spectra respectively, with other symbols defined as in equation 48. In this way only the higher resolution near-detector response needs to be inverted.…”