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Neutrino detectors

The second-generation neutrino experiments in Europe focus on the low energy part of the solar neutrino spectrum. They are the Gallium Neutrino Observatory (GNO) and BOREXINO, both located at the Gran Sasso Laboratory. GNO is a continuation of GALLEX with improved technology and target mass. It will provide accurate information on the integral $\nu_e$-spectrum for $E_\nu$>233 keV. BOREXINO concentrates on the detection of the $862\,$keV ⁷Be neutrino line by means of $\nu$-e scattering in a 100 t liquid scintillator target.

    SUPERKAMIOKANDE and the $1000\,$t $D_2{\rm O}$ Cerenkov detector at the Sudbury Neutrino Observatory (SNO) focus on the spectroscopy of the high energy part of the neutrino spectrum. SUPERKAMIOKANDE with its spectral shape information can give an unambiguous prove for neutrino oscillations by deviations from the expected $\beta$-spectrum. The SNO experiment provides information on neutral and charged current interactions with deuterium: $\nu +~^2$H $\rightarrow n + p + \nu$ and $\nu_e +~^2$H $\rightarrow p+p+e^-$. The first reaction is also sensitive to muon neutrinos and thus to neutrino oscillations. Both experiments will also be able to observe supernova neutrinos.

    The challenging construction of large volume (up to a km³ water or ice) high energy neutrino detectors has just begun. The European involvement is strong, both in the Lake Baikal (Russia) deep lake detector and in AMANDA, a south pole deep ice experiment. Furthermore, the NESTOR deep sea project near Pylos, Greece, and the French project ANTARES are in an early development phase.