Solving the Solar Neutrino Problem 2 Km Underground — the Sudbury Neutrino Observatory

The Sudbury Neutrino Observatory (SNO) is capable of measuring simultaneously the flux of electron-type neutrinos and the total flux of all active flavours of neu-trinos originating from the Sun. A model-independent test of neutrino flavour transformation was performed by comparing these two measurements. Assuming an undistorted neutrino energy spectrum, this transformation has been definitively demonstrated in the pure D 2 O phase of the SNO experiment. In the second phase with dissolved NaCl in the D 2 O, the total active solar neutrino flux was measured without any assumption on the energy dependence of flavour transformation. In this talk, results from these measurements, their physics implications and the current status of the SNO experiment are presented.