Neutrinos, Quarks and Leon Lederman

by Nicholas Mee on November 9, 2018

Leon Lederman (1922-2018)

Leon Lederman died at the age of 96 on 3 October 2018. Lederman was one of the leading particle physicists of the twentieth century and a key architect of the Standard Model.

Working with Melvin Schwartz and Jack Steinberger at Brookhaven Laboratory in New York in 1962, Lederman was co-discoverer of the second type of neutrino—the muon neutrino.

The neutrino was originally postulated by Wolfgang Pauli in 1930. Radioactive nuclei such as carbon-14 undergo beta decay in which a neutron in the nucleus of the atom is transformed into a proton and a high energy electron is emitted. Pauli proposed that an (anti-)neutrino is emitted along with the electron, escaping with some of the released energy. Neutrinos interact very weakly, so it was not until 1956 that this idea was confirmed experimentally using the flux of neutrinos produced by a nuclear power station.

The neutrinos produced in beta decay are associated with electrons. On the very rare occasions when they interact with a neutron, the neutron transforms into a proton and the neutrino transforms into an electron. Lederman, Schwartz and Steinberger showed that there was another type of neutrino that is associated with the muon—a particle discovered in 1936 that behaves like a very heavy electron. The muon carries the same charges as an electron and interacts in the same way as an electron, but has 207 times as much mass.

The particles of the Standard Model.

These particles are now collected together into the Standard Model table of particles. The electron and the first type of neutrino—the electron neutrino—belong to the first generation, and the muon and muon neutrino are their relatives in the second generation. Lederman, Schwartz and Steinberger were awarded the 1988 Nobel Prize in Physics for the discovery of the muon neutrino.

Lederman went on to work at Fermilab (Fermi National Accelerator Laboratory), which is located near Chicago. In 1977 he led the team that discovered the bottom quark, which was the first quark to be discovered in the third generation of matter particles. The following year Lederman was appointed Director of Fermilab, a position he held until 1989.

Fermilab (Credit: FNAL)

Fermilab would go on to discover the other missing matter particles of the Standard Model with its record-breaking Tevatron collider. The discovery of the top quark was announced in 1995 and the existence of the third generation neutrino—the tauon neutrino—was established in the year 2000. The only missing particle predicted by the Standard Model was now the Higgs boson.

Lederman was a strong advocate for a plan to build an enormous particle accelerator in Texas known as the Superconducting Super Collider (SSC). In an attempt to persuade the doubters in Congress, Lederman and Dick Teresi published a book in 1993 called The God Particle, Lederman’s dubious nickname for the Higgs boson. Unfortunately the SSC project was cancelled. If it had gone ahead it is very likely that the Higgs boson would have been discovered in America and not Europe.

Further Information

A video version of this tribute is available here: A Tribute to Leon Lederman on The Cosmic Mystery Tour YouTube Channel. Please don’t forget to subscribe to the YouTube channel.

 

There is a lot more about Fermilab, the development of the standard model and the history of particle physics in my book Higgs Force.

 

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