Photo from the Nobel Foundation archive.
Born: 25 May 1921, Bad Kissingen, Germany
Affiliation at the time of the award: CERN, Geneva, Switzerland
Prize motivation: "for the neutrino beam method and the demonstration of the doublet structure of the leptons through the discovery of the muon neutrino."
Prize share: 1/3
In decays of certain elementary particles, neutrinos are produced; particles that occasionally interact with matter to produce electrons. Jack Steinberger, Leon Lederman, and Melvin Schwartz managed to create a beam of neutrinos using a high-energy accelerator. In 1962, they discovered that, in some cases, instead of producing an electron, a muon (200 times heavier than an electron) was produced, proving the existence of a new type of neutrino, the muon neutrino. These particles, collectively called "leptons", could then be systematically classified in families.