Abstract
A direct approach to resolve the solar-neutrino problem would be to observe neutrinos by use of both neutral-current and charged-current reactions. Then, the total neutrino flux and the electron-neutrino flux would be separately determined to provide independent tests of the neutrino-oscillation hypothesis and the standard solar model. A large heavy-water Cherenkov detector, sensitive to neutrinos from B8 decay via the neutral-curent reaction ν+dν+p+n and the charged-current reaction νe+de+p+p, is suggested for this purpose.