1933, Enrico Fermi had developed a theory of beta decay to include the neutrino, presumed to be massless as well as chargeless. Treating the beta decay as a transition that depended upon the strength of coupling between the initial and final states, Fermi developed a relationship which is now referred to as Fermi’s Golden Rule. […]
1931 – Pauli presents hypothetical “neutron” particle
Historically, the study of beta decay provided the first physical evidence of the neutrino. In 1911, Lise Meitner and Otto Hahn performed an experiment that showed that the energies of electrons emitted by beta decay had a continuous rather than discrete spectrum. This was in apparent contradiction to the law of conservation of energy, as […]