text: In the original solution of a first-order equation comprised of three alpha matrices and a beta matrix, this particle's wavefunction has a positive imaginary exponential.
full_question: In the original solution of a first-order equation comprised of three alpha matrices and a beta matrix, this particle's wavefunction has a positive imaginary exponential. In a famous photograph, one of these particles travels through a lead plate and loses its radius of curvature as it travels upward. Fluorodeoxyglucose is a source of these particles. Pauli and Weisskopf explained how this particle gives a (*) negative energy density in the Klein-Gordon equation. When a photon of energy greater than 1.02 MeV undergoes pair production, an electron and this particle are formed. The Dirac equation predicted this particle as a "hole" in a sea of electrons. For 10 points, name this particle symbolized e+, which is the antiparticle of the electron.
first_sentence: In the original solution of a first-order equation comprised of three alpha matrices and a beta matrix, this particle's wavefunction has a positive imaginary exponential.
raw_answer: positron [or antielectron]