For 10 points, identify this particle discovered by Carl Anderson, an anti-electron usually written as e-plus.
Project PAMELA discovered an abundance of these particles while orbiting the Earth in 2008, though the theory of cosmic strings might explain the result. FDG is a radioactive tracer whose emission of these particles results in annihilation, and the resulting gamma rays feature in a medical imaging technique named for them. They were predicted as a consequence of the Dirac equation, and their existence was proven by sending cosmic rays through a cloud chamber leading to diverging beams of charged particles, a result explainable by antimatter. For 10 points, identify this particle discovered by Carl Anderson, an anti-electron usually written as e-plus.
Project PAMELA discovered an abundance of these particles while orbiting the Earth in 2008, though the theory of cosmic strings might explain the result.
{positrons} [accept {anti}-{electron} before mentioned]