Bruno Pontecorvo was born on 22 August, 1913, in Marina di Pisa. He studied in Roma where he got his PhD. He worked with Fermi during the 1930’s but, facing italian fascism, he had to escape to France where he worked with Joliot-Curie. In June 1940, he then had to escape to the US. He worked later in Canada (Chalk River), then in England (Harwell) from 1948. In August 1950, he suddenly disappeared, during a vacation in Italy. It was known only 5 years later that he defected to the USSR, where he had decided to spend the rest of his life, with his family. He died on 24 September 1993 in Dubna, Russia.
He is a central actor who provided many new ideas and proposed many experiments. He contributed with Enrico Fermi to the study of weak interactions and brought interesting results concerning the neutrino. He showed in the 50’s that the muon decays into an electron and two neutrinos and that the muon is fundamentally different from the electron, that it represents a second lepton family.
Pontecorvo proposed also to detect the neutrinos produced by nuclear reactors using a chloride solution that was finally used by Davis to detect solar neutrinos. He proposed the oscillation of neutrino to interpret the deficit of solar neutrinos and proposed to study such oscillations to measure the neutrino mass.
Frederick Reines was born in 1918, in Paterson, New Jersey. He studied at the Hoboken Institute of Technology, New Jersey, and received his PhD in 1944, in New York University. From 1944 until 1959, he was employed at the Los Alamos laboratory and spent some years hunting the neutrino particle. Together with Clyde Cowan, he made the “Poltergheist project”, an experiment to detect a few of the billions of billions of neutrinos emitted by the nuclear reactor of Hanford every second. The first result in 1953 was not conclusive. After detector improvements, they finally detect neutrinos near the reactor of the Savannah River nuclear power plant. Until 1966, he was then professor and director at the physics department of “Case Institute of Technology”. He worked since 1966 at the physics and astronomy department of the California University and continued his interest in neutrino physics. F. Reines passed away on 26thof August 1998. The Irvine group of the SuperKamiokande experiment made a very nice page about him.
Clyde Cowan was born in Detroit, Michigan, in 1919. After a bachelor in chemistry engineering in 1940 and a service in the US army from 1941 to 1946, he got his PhD from Washington University in 1949 before working at the Los Alamos laboratory where he encountered F. Reines. In 1951, they started to think about detection of neutrinos, first near nuclear explosions, then near nuclear power plants. After their 1956 success in the experimental discovery of the neutrino, Clyde Cowan went to the Catholic University of Washington where he taught until his premature death in 1974.
The following list of people is a biased selection of the authors. We tried to list here most of the physicists who made major steps in the knowledge of the neutrino and/or represent the experimental collaborations (many people) who made such major steps.
Tsung-Dao Lee was born in Shanghai in 1926. He came to USA in 1946 to pursue his studies at the Chicago university, where he received his PhD under the direction of Enrico Fermi. He tought at Chicago university, then at Berkeley university and at Princeton university, before joining Columbia university in 1953. Since 1976, he contributed in general relativity, field theory on random net and high temperature supra-conductors.
Chen-Ning Yang was born in China in 1922. After his studies in Beijing, then in the National Southwestern Associated University, in Lianda, he was awarded in 1945 a US scholarship that allowed him to study at the University of Chicago, where he received his PhD in 1948. In 1949 he was invited to do his research at the Institute for Advanced Study in Princeton, New Jersey, where he began a period of fruitful collaboration with Tsung-Dao Lee.
Both T.D Lee and C.N. Yang contributed greatly to the better knowledge of weak interaction. In particular, they predicted in 1956 the violation of parity symetry in the weak interactions, that was confirmed a few months later by the Cobalt 60 experiment of Ambler, Hayward, Hobbes, Hudson and Wu.
For this work, Lee and Yang received the physics Nobel Prize in 1957. Moreover, they initiated and participated actively in the discovery of the numu by Steinberger, Lederman and Schwartz team in 1962. T.D. Lee also contributed to theoretical work about the spontaneous CP symetry breaking in 1974….
Chien-Shiung Wu was born in China in 1912. After studying at the Nanjing University, she went to USA in 1936 to do her PhD, that shw obtained in 1940 from the Berkeley University. In 1945, she became Associate Professor at the Columbia University, New York. She was considered as an expert in beta decay and in chemistry of radioactive elements. In 1957, she conceived and constructed with Ambler, Hayward, Hobbes and Hudson the first experiment able to show that weak interactions can distinguish left from right (Phys. Rev. 105, 1413 (1957)). This cobalt 60 experiment proved that Lee and Yang hypothesis on parity violation by weak interaction was right. Pauli had to admit that “God is a little left-handed”.
Maurice Goldhaber was born in Lemberg, Austria now called Lviv, Ukraine . He studied at the University of Berlin and earned his doctorate at Cambridge University in 1936. In 1934, he worked with James Chadwick at the Cavendish Laboratory in Cambridge, on the photodisintegration of the deuterium nucleus and on the neutron decay. After earning his PhD in 1936 at Cambridge University, he went to the US, at the University of Illinois, before joining in 1950 joined Brookhaven National Laboratory
In the 1950s he and colleagues conducted a revolutionary tabletop experiment that demonstrated that the neutrino spins in only one direction; it has only left helicity. This experiment was a major step in the neutrino studies and, with the experiment of C.S. Wu, pointed out the fact that weak interaction is a breaker of symetries.
From 1961 to 1973, M. Goldhaber was Director of Brookhaven National Laboratory. After retirement, he participated to IMB and SUerKamkiokande experiments. Among other awards, he was awarded the Enrico Fermi Award in 1998.
Leon Lederman was born in 1922, in New York. He pursued his studies until 1943, when he joined the American army. In 1946, he studied at the Columbia University where he received his PhD in 1951. In 1958, he became professor and went for a sabbatical year at CERN. Coming back in Columbia, he associated with J. Steinberger and M. Schwartz to propose an experiment which gave him the Physics Nobel Prize in 1988.
From 1961 until 1978, he led the Brookhaven laboratory, where he participated to the discovery of the b quark (bottom). In 1979, he became director of the Fermilab and led the construction of the Tevatron (which allowed the CDF experiment to discover the top quark). In 1989, he joined the Chicago University and created in 1995, at Fermilab, a scientific educative center, which is a model of scientific teaching, which triggered G. Charpak for his French experience la “main a la pate”.
Melvin Schwartz was born in 1932. He studied at Columbia University and received his PhD in 1958, after a two years work at Brookhaven laboratory. In 1963, he became professor at Columbia University, one year after his discovery of the numu neutrino, with J. Steinberger, L. Lederman, J.M Gaillard, G. Danby, K. Goulianos, N. Mistry, T.D Lee and C.N. Yang, at the Brookhaven AGS proton accelerator. In 1966, he became professor at Stanford University. He then funded in 1983 a company of computing network, which he left in 1991 to return as a professor to Columbia University, where he worked on quark-gluon plasma.
Jack Steinberger was born in 1921, in Bad Kissingen, Germany. In 1934, he had to run away from Nazism and pursued his studies of chemistry in the Illinois Institute of Technology, USA. In 1942, he joined the American army and was affected to the radar stations, where he learned physics. In 1945, he followed the course of Enrico Fermi at the Chicago University, where he received his PhD. In 1948, he tought in Princeton University, then Berkeley in California, and finally in Columbia university from 1950 to 1968, where he participated to bubble chambers experiments and to the spark chamber experiment which discovered the neutrino nu_mu, in 1962. He then went to CERN until 1986, when he became associate professor of Pisa University. In 1988, he shared the Physics Nobel Prize with Schwartz and Lederman for the discovery of the neutrino nu_mu. He died in december 2020.
Born on 30th of December 1934 in Louisiana, he studied in Harvard and received his PhD in 1961. After a stay at Indiana University, then in California Institute of Technology, he became professor at the Princeton University in 1971.
During more than 30 years, John Bahcall studied with many details the thermonuclear reactions that makes the Sun shine. The present Standard Solar Model, on which lays the predictions of the solar neutrinos flux has a great debt to his work. He participated with Ray Davis to the first experiments that tried to detect solar neutrinos. During many years, the deficit of solar neutrinos was attributed to a wrong modelisation leading to a wrong prediction of the neutrino flux by J. Bahcall. Several hints and finally the results of the SNO experiment proved that neutrino oscillations were the culprit and that Bahcall’s work was correct. By the way, he has a very documented web site
Davis was born in 1914 in Washington, D.C. He studied at the University of Maryland and received a Ph.D. from Yale University in physical chemistry in 1942. In 1948, he joined Brookhaven National Laboratory, and dedicated his career to the study of neutrinos.
Following an idea of Bruno Pontecorvo, Davis investigated the detection of neutrinos by their interaction with Chlorine that produces radioactive Argon. He first tried to detect neutrinos from the Brookhaven reactor, then from the Savannah River nuclear reactor in 1955, without success.
Ray Davis then conceived a pioneering experiment for the solar neutrinos detection, in the Homestake mine, in South Dakota. Made of a large cylinder filled with 600 tons of chlorine industrial solvent, it ran over about 30 years and repeatedly confirmed that it only detected one third of the number of solar neutrinos predicted by J. Bahcall. The discrepancy gave a hint towards the oscillation of solar neutrinos.
He shared the Nobel Prize in Physics in 2002 with Japanese physicist Masatoshi Koshiba and Italian Riccardo Giacconi for pioneering contributions towards the detection of solar neutrinos.
André Lagarrigue was born in 1924, in Aurillac, France. After his admission at Ecole Polytechnique in 1945, he developed an interest in experimental physics. He received his PhD in 1952, with a study of the experimental properties of muon decay and worked in the following years on heavy liquid bubble chambers, suitable for neutrino detection.
After attending a conference, in 1963, on the newest developments in the field of neutrino physics, Lagarrigue came up with the idea to construct a heavy liquid chamber for detection of neutrinos. This led him to propose and lead an experiment called Gargamelle, which made several discoveries. One of them was the discovery of the neutral currents which is one of the main step in understanding of the weak interaction and thus of the neutrino physics.
In 1969 he became director of Orsay Linear Accelerator Laboratory, until his sudden death in 1975.
Martin Perl was born in 1927. He studied chemistry in Brooklyn Polytechnic Institute and received his PhD in Columbia University in 1961. After teaching some time at the Michigan University, he joined in 1963 the Stanford Accelerator laboratory, where he spent 12 years hunting for leptons.
In 1975, thanks to the new collision machine SPEAR, he discovered the tau lepton, but his discovery was not confirmed by others experiments. He spent may be the four most awful years of his life until 1979 where the tau was seen again. His discovery of the tau was the confirmation of the existence of three families of leptons and a strong hint for the existence of the tau neutrino ντ.
Masatoshi Koshiba was born in 1926. After studying in the University of Tokyo, he went to University of Rochester, New York, where he received a Ph.D. in physics in 1955. After a career of professor, mainly at the university of Chicago and at the University of Tokyo where he became Emeritus Professor in 1987, he went to the Tokai university from 1987 to 1997. During this period, he was mainly involved in neutrino studies and was the lead of the Kamiokande experiment which confirmed the solar neutrino deficit observed by R. Davis and was one of the neutrino detectors having seen the neutrino burst coming from the supernova SN1987A. He then participated to the Superkamiokande experiment which, in 1998, announced the long waited evidence for neutrino oscillation. At the university of Tokyo, in 1986, he was the mentor of Takaaki Kajita, who later led SuperKamiokande. In 2002, he shared the Nobel Prize in Physics with Raymond Davis Jr. and Riccardo Giacconi for his contributions to the detection of cosmic neutrinos. He died in november 2020.
Herbert Hwa-sen Chen was born in Chunking, China in 1942. After immigrating to the United States with his family in 1955, he studied in Massachusetts and earned a bachelor of science degree in physics from the CalTech in 1964. He then earned his doctorate in theoretical physics from Princeton University in 1968 and joined the newly formed physics department at University of California, Irvine as a postdoctoral theorist in 1968 and worked within Frederick Reines’ Neutrino Group. Chen began a long-term experimental program for the development of methods to measure the properties of neutrinos, working on elastic neutrino-electron scattering.
In 1984 he realized that the deuterium of heavy water could be used as a detector that would distinguish the flavors of solar neutrinos. This led him to develop plans for the Sudbury Neutrino Observatory (SNO), thus to initiate the experiment which put the final result to the solar neutrino problem.
Arthur McDonald was born in Sydney, Canada, in 1943. He studied at Dalhousie University and then at the California Institute of Technology, where he earned his PhD in 1969, under advisor William Fowler. Following an idea of Herb Chen who suggested the advantages of using heavy water as a detector for solar neutrinos, Chen, McDonald, and collaborators formed the Sudbury Neutrino Observatory (SNO) to exploit this idea from 1986.
SNO is a detector facility using 1000 tonnes of heavy water located 2100 meters underground in the mine of Sudbury, Ontario. Arthur McDonald led the SNO experiment which in 2001 reported observations that showed that electron neutrinos from the Sun were oscillating into muon and tau neutrinos. McDonald shared the 2015 Nobel Prize in Physics for the discovery of neutrino oscillations and the demonstration that neutrinos have mass.
Kajita was born in 1959. He studied physics at the Saitama University and received his doctorate in 1986 at the University of Tokyo.
In 1998, Kajita’s team found with the SuperKamiokande detector that neutrino coming from cosmic rays oscillate between two flavours. This discovery was a main hint to prove the existence of neutrino oscillation. In 2015, Kajita shared the Nobel Prize in Physics with Canadian physicist Arthur McDonald of the SNO experiment. SuperKamiokande and SNO solved the longstanding Solar neutrino problem, which was a major discrepancy between the predicted and measured Solar neutrino fluxes,
Kajita is currently director of the Center for Cosmic Neutrinos at the Institute for Cosmic Ray Research (ICRR) and is the principal investigator of another ICRR project located at the Kamioka Observatory, the KAGRA gravitational wave detector.
Stanislav Mikheyev, after studying at Moscow State University until 1965, became a researcher at Lebedev Physical Institute. In 1970 he started to work at the Institute for Nuclear Research of the USSR Academy of Sciences, where he earned his Ph.D. in physics in 1983.
One of his first major contributions to neutrino physics was in 1985, when he worked with Alexei Smirnov on the oscillation of neutrinos in matter with varying density , which is called now the MSW effect.
Alexei Smirnov studied at Moscow State University until 1974. In 1977, he began to work at the Institute for Nuclear Research of the USSR Academy of Sciences o, where, in 1989, he received a degree of Doctor of Physical and Mathematical sciences. He then joined International Centre for Theoretical Physics (ICTP) in Trieste, Italy in 1992. He worked in 1984-1985, together with Stanislav Mikheyev, on effects of resonance enhancement of neutrino oscillations in matter, called now the MSW effect. It has been used to propose solutions to the solar neutrino problem and is now used also for detection of neutrinos of various origins propagating in the Earth.
Lincoln Wolfenstein was born in 1923 in Cleveland, Ohio. He obtained his PhD in 1949 from the University of Chicago and then worked at Carnegie Mellon University. He was a phenomenologist whose work focused the weak interaction. For instance, he did some early work on what is now called the Cabibbo–Kobayashi–Maskawa quark mixing matrix.
In 1978, he noted that the presence of electrons in Earth and Solar matter could affect neutrino propagation. This pionnering work was then developped by A. Smirnov and Stanislav Mikheyev and led to a better understanding of the solar neutrino problem.
In 1986, during a Moriond Conference, Albert Messiah proposed to name MSW the effect discovered by Wolfenstein and formalized by Smirnov and Mikheyev.
Wolfenstein, Smirnov and Mikheyev received the 2006 Bruno Pontecorvo Prize for their study of the influence of matter on neutrino oscillations.