PROBING THE SOLAR MSW LARGE MIXING ANGLE SOLUTION WITH TERRESTRIAL (NU)OVER-BAR-(E) FROM EUROPEAN NUCLEAR-REACTORS WITH BOREXINO

Electron anti-neutrinos ((nu)over-bar(e)) emitted from distant (simila r-to 800 km) nuclear reactors will be measurable with the BOREXINO det ector at the Gran Sasso Underground Laboratory. From this signal neutr ino oscillation parameters can be assessed for Delta m(2) greater-than 10(-6)eV(2) and sin(2) 2- greater-than 0.3. In particular one of the currently favoured Delta m(2)-sin(2) 2- parameter regions, i.e. the la rge mixing angle MSW solution which is proposed in order to resolve th e solar neutrino problem, can be tested for the first time in a terres trial laboratory experiment. The impact of nonreactor (nu)over-bar(e)' s, in particular the signal of geo-physical neutrinos and potential ba ckgrounds are discussed.