Two answers required. Collisions of these two particles were detected by early B factories like the BaBar experiment. These two particles interact in Bhabha scattering. (0[1])Blackett and Occhialini’s discovery of one of these particles by observing its curving relative to the other was scooped (20[1])by a scientist (20[1])who observed their tracks from cosmic rays in a (*) cloud chamber. (10[1])Radiotracers like carbon-11 emit one of these particles whose interaction with the other is detected by gamma cameras. These two particles correspond to opposite-sign solutions to the Dirac equation (10[1])according to hole theory. These two particles have opposite charges with magnitudes equal to the elementary charge. For 10 points, name this negatively-charged nucleus-orbiting fermion and its antiparticle. (10[1])■END■