The physicist who first confirmed the existence of positrons experimentally was Carl Anderson in 1932. Anderson was studying cosmic rays using a cloud chamber, a device that allowed him to observe the paths of charged particles. While investigating the particles in cosmic rays, he noticed a particle that behaved similarly to an electron but had a positive charge instead of a negative one. This particle, which was moving in the opposite direction to an electron in a magnetic field, was identified as the positron, the antiparticle of the electron.