Anderson, Carl David

The American Carl David Anderson (1905 - 1991), son to Swedish immigrants, was an experimental physicist.

In 1932, during the course of his investigations into cosmic rays, he encountered unexpected particle tracks in his cloud chamber that he interpreted as having been created by a particle with the same mass as the electron, but with opposite electric charge. This discovery validated Paul Dirac's theoretical prediction of the positron.

In 1936, he discovered also the muon.