The neutrino was first postulated in 1931 by Wolfgang Pauli to explain the continuous spectrum of beta decay, the decay of a neutron into a proton and an electron. Pauli theorized that an undetected particle was carrying away the observed difference between the energy and angular momentum of the initial and final particles. Because of their "ghostly" properties, the first experimental detection of neutrinos had to wait until about 25 years after they were first discussed. In 1956 Clyde Cowan, Frederick Reines, F. B. Harrison, H. W. Kruse, and A. D. McGuire published the article "Detection of the Free Neutrino: a Confirmation" in Science, a result that was rewarded with the 1995 Nobel Prize. The name neutrino was coined by Enrico Fermi as a word play on neutrone, the Italian name of the neutron particle. (Neutrone in Italian also means big and neutral, and neutrino means small and neutral.) In 1962 Leon M. Lederman, Melvin Schwartz and Jack Steinberger found out that more than one type of neutrino exists.