In an earlier post titled “Recent findings of neutrino experiments (as of August 2015) ” I mentioned that neutrino physics is the future of particle physics. The findings of the neutrino experiments are probably more relevant than the findings of the LHC experiments when it comes to answering the most fundamental questions. Apparently the Nobel committee thinks the same way. Every milestone in neutrino physics was recognized by a Nobel Prize. I listed the specific years and some historical info about those awards in the section titled “Previous Nobel Prizes Recognizing Neutrino Physics” below.
This year’s (2015) Nobel Prize in Physics was awarded to Takaaki Kajita and Arthur B. McDonald for leading large teams of physicists and engineers to the experimental confirmation of neutrino oscillations. Takaaki Kajita is the director of the Center for Cosmic Neutrinos at the Institute for Cosmic Ray Research (ICRR) which is affiliated with the University of Tokyo. Arthur B. McDonald was the director of the Sudbury Neutrino Observatory (SNO). He is currently the University Research Chair at Queen’s University and a board member at Perimeter Institute for Theoretical Physics.
Previous Nobel Prizes Recognizing Neutrino Physics
The physicist who argued that neutrinos (electrically neutral, very light, spin=1/2 particles) must exist is Wolfgang Pauli. He came up with the neutrino idea in 1930. He received the Nobel Prize in Physics in 1945. Even though the Nobel committee cited his discovery of the “Exclusion Principle” the prize was really a recognition of his many contributions including the neutrino idea. Pauli did not name the particle. The name “neutrino” was given by Enrico Fermi who received the Nobel Prize in Physics in 1938 for his work on neutrons. Note the difference in the name. A neutron is very different from a neutrino. Neutrons live inside the nucleus of an atom. Neutrons are composite particles; inside a neutron there are quarks and gluons. Neutrinos on the other hand are truly elementary.
Neutrinos are ghostly particles that fill the universe. On average, in each cm-cube there are about 300 neutrinos. Neutrinos rarely interact with matter. This is the reason why neutrinos cannot be confined. I will prepare a post titled “Neutrino Resources” to put together the most relevant links. In that post I will also summarize what we currently know about the neutrinos and list the open questions.
Neutrino was experimentally discovered in 1956 by F. Reines and C.L. Cowan Jr. in the Savannah River nuclear reactor in South Carolina. Nuclear reactors produce electron type anti-neutrinos. So, historically speaking, the electron type anti-neutrino was discovered first. F. Reines had to wait 39 years for his Nobel Prize. He shared the prize with Martin L. Perl in 1995 who discovered the tau particle in 1975.
The muon type neutrino was discovered by L.M. Lederman, M. Schwartz and J.Steinberger in 1962 at the Brookhaven National Laboratory. They received their Nobel Prize for this discovery in 1988. I was there as a postdoc when Leon M. Lederman celebrated his award outside his Fermilab office in a fine October morning in 1988. He was ecstatic that morning.
In 2002, Raymond Davis, Jr. shared the Nobel Prize in Physics with Masotoshi Koshiba and Riccardo Giacconi for his contributions to neutrino physics. He was 88 years old when awarded the prize. The oldest Nobel Laureate in Physics to date. Davis was the lead scientist behind the Homestake Experiment, the large-scale radiochemical neutrino detector which first detected evidence of neutrinos from the sun.
The tau type neutrino was observed directly for the first time at Fermilab (E872 experiment) in 1997, the results were announced in 2000. No Nobel Prize for the discovery of the tau type neutrino yet. I guess they have to wait 20-30 years like the others.