Positron discovery by Carl Anderson enables modern medical imaging

In August 1932, physicist Carl Anderson accidentally discovered the positron, the first detected particle of antimatter, while studying cosmic rays at the California Institute of Technology. Using a cloud chamber within a magnetic field to observe particle trajectories, Anderson identified a particle with the same mass as an electron but with a positive charge.

This empirical discovery confirmed a theoretical prediction made in 1928 by Paul Dirac, whose equations relating quantum mechanics and special relativity suggested the existence of a mirror particle to the electron.

Decades after its discovery, the positron has become a vital tool in modern medicine. Positron Emission Tomography (PET) scans utilize these particles to visualize metabolic activity in tissues, assisting doctors in locating tumors and studying neurodegenerative diseases.