Most neutrino experiments must address the flux of cosmic rays that bombard the earth's surface. The higher energy (>50 MeV or so) neutrino experiments often cover or surround the primary detector with a "veto" detector which reveals when a cosmic ray passes into the primary detector, allowing the corresponding activity in the primary detector to be ignored ("vetoed").That adresses my query about radioactive decay thank yoy fellow ac but back to the original thread to use neutrinos as an imageing device is almost beyong science fiction.Having said that I do beleive there is something not natural about the Moon ?.