Solar Neutrino Experiments: The Next Generation

In the next few years, three massive new solar neutrino detectors will generate large amounts of precise data that should have a major impact on our understanding of how the Sun shines and how neutrinos behave. They are Super Kamiokande, in the mountains west of Tokyo; the Sudbury Neutrino Observatory (SNO) in a northern Ontario mine and Borexino, in the Apennines east of Rome. Each of these detectors was conceived and is being built by a sizable international collaboration. Each is housed in an underground laboratory shielded from cosmic ray products other than neutrinos and very energetic muons by a mile or so of earth. Super Kamiokande, the most massive of the three, is a 50‐kiloton water‐Cerenkov detector. (See figure 1 and the cover of this issue.) In all of these new detectors, sophisticated electronics will record and analyze the individual neutrino collision events. Each detector will register more neutrino interactions in two months than all of the previous solar neutrino experiments have detected in a quarter of a century.