7D  NUCLEAR PHYSICS
7D10  Radioactivity
            .20 Half Life
            .60 Nuclear Shielding
            .80 Cosmic Rays
7D20  Nuclear Reactions
            .10 Mousetrap Chain Reaction
7D30  Particle Detectors
7D40  NMR
7D50  Models of the Nucleus
            .20 Rutherford Scattering