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Lee et Yang






And many


For the birth of the neutrino particle, beta radioactivity had to be known. Henri Becquerel, in 1896, did the first experiments on the radioactivity phenomena. Pierre and Marie Curie discovered in 1898 the radium, two millions times more radioactive than the uranium salts used by Becquerel. Those three scientists were at the origin of the fundamental researches on the atomic nucleus undertaken in the following years, which gave us, among others, the discovery of the neutrino, 50 years later.

Marie and Pierre Curie in their laboratory

Marie Curie is born in 1867 in Warsow, Poland. In 1891, thanks to her sister, she comes to France to study chemistry in Sorbonne and she marries Pierre Curie in 1895. In 1897, while doing her thesis on uranium radiation of Becquerel, she hits a problem: why is the pechblende, a mineral from which is extracted uranium, more radioactive than uranium? In July of 1898, she discovers in pechblende a new radioactive chemical element that she calls the polonium. In December of 1898, Pierre and Marie isolate an other new chemical element, two millions more radioactive than uranium: the radium. Marie shares with Pierre Curie and Henri Becquerel the Physics Nobel price in 1903 and receives in 1911 the Chemistry Nobel price for her work of pure radium isolation. After the war in 1914-18, she travels around the world to find money resources in order the buy radium that her laboratory needs. She left our world on 4th of July 1934, in Paris, one year before her daughter share the physics Nobel price with Pierre Joliot.

James Chadwick

In 1914, James Chadwick shows that energy spectrum of the beta radioactivity electrons is a continuum. This problem of the continuous beta spectrum will lead 16 years later to the Pauli hypothesis and will make Niels Bohr anxious about the energy conservation principle. In 1932, Chadwick discovers the neutron, the proton's partner in atomic nucleus. With this discovery he participates indirectly to the baptism of "neutrino" by Fermi and receives the pysics Nobel price.

Wolfgang PAULI

The idea of neutrino was born only in 1930, when Wolfgang Pauli tried a desperate saving of the "energy conservation principle". In order to explain the continuous beta spectrum, he invented a new light particle, neutral and interacting very few with the other particles of matter.

Wolfgang Pauli is born on April 25th 1900, in Vienna, Austria. At the age of 18, he goes to Munich for studying physics with Sommerfeld. He then writes a 200 pages article about the relativity, which impresses Sommerfeld and Einstein. He obtains his PhD in 1922. In 1924, he creates the exclusion principle which now is called often "Pauli principle" and brings a great step to the still young quantum mechanics. From 1924 until 1928, he teaches in Hamburg, then in Zurich. In 1930, he invents the neutrino, which will be named 3 years later by Enrico Fermi. In 1935, he stays some time in Princeton university. In 1945, he receives the Physics Nobel price for his fabulous idea of the exclusion principle: two electrons, and more generally two fermions, cannot have the same quantum state (position, momentum, mass, spin). One could say that all the electrons of the universe are different.
In 1958, Pauli dies in Zurich, 3 years after Einstein and 4 years after Fermi.

Bohr and Pauli looking at a spinning macroscopic particle

Niels BOHR

He was some time a fervent partisan of throwing away the "energy conservation principle". He prefered to abandon this fundamental principle instead of inventing a new hypothetical particle so difficult to detect.

Niels Bohr is born in Copenhague, on 7th of October 1885. He studies at the Copenhague university and obtains his PhD in 1911. He goes then to Cambridge to study nuclear physics with J.J. Thomson, then in Manchester with E. Rutherford. From 1913 until 1915, he elaborates, inspired by the atomic model of Rutherford, the first quantum construction of the atom. This is an empirical model where the electron orbital motion around the nucleus is quantified: an atom can emit or absorb light only by transferring an electron from a quantum orbit to an other. The quantum mechanics begins its life. He receives for this contribution the physics Nobel price in 1922.
In 1916, he returns as a professor at the Copenhague university and becomes in 1920 the director of the new Institute of Theoretical Physics of Copenhague. This is the beginning of the famous "Copenhague School" which tries to associate the measurable quantities with the quantum properties of particles. In 1939, he gives informations to the american scientists about the work undertaken by Otto Hahn and Fritz Strassmann in Germany on nuclear fission and demonstrates that uranium 235 is the good isotope for a nuclear bomb. In 1940, Danemark is occupied by german troops, Bohr life is threatened and he goes to Sweden, then to England and finally to USA where he participates to the Manhattan project, at Los Alamos. He opposes to the military secret policy and asks then an international control against the proliferation of atomic weapons. In 1945, he goes back to Copenhague and participates in 1955 to the creation of the first conference "Atom for Peace". He dies in Copenhague on 18th of November 1962.

Enrico FERMI

In 1933, Enrico Fermi names the mysterious particle of Pauli. From that date it will the "neutrino". At the end of 1933, he supposes the existence of the neutrino and elaborates his theory of beta decay and weak interaction, a great stone until 1970 (and even until now!) for the description of neutrino interactions.

Enrico Fermi was born in Roma on 29th of September 1901. He goes to school in Roma and continues his studies in Pisa. He becomes in 1926 professor of theoretical physics at Roma university. He participates to the elaboration of a new type of particle statistics (the Fermi-Dirac statistics) describing the general behavior of electrons.
In 1934, he interests in artificial radioactivity obtained by bombing a nuclear target with neutrons (the first step to the nuclear chain reaction). He receives for this work the physics Nobel price in 1938. At this occasion, he runs away from the fascist government of Italy and becomes professor at the Columbia university, USA. There, he leads, under the Manhattan project, the team which makes the first atomic reactor (first controlled nuclear chain reaction) in Chicago and then works until 1945 at Los Alamos. After the end of the war, he opposes to the development of the fusion bomb and becomes also director of the new Institute of Nuclear Physics of Chicago (often called today the Fermilab, the equivalent of Cern in USA). He dies on 28th of November 1954 in Chicago, from a cancer (probably caused by the radiations he received during his works).

Hans BETHE and Rudolf PEIERLS

As early as 1934, Hans Bethe and Rudolf Peierls show that the cross section of neutrinos (that is their probability of interacting with matter) should be extremely small: billions of times smaller than the one of electrons.

Bethe was also a precursor in the understanding of the origin of sun's light, hence in the elaboration of the models that today predict the solar neutrinos flux.

Frederick REINES and Clyde COWAN

They try, as soon as 1952, to give evidence for neutrinos. They try to detect, with a cadmium-water target, some of the 100 billions of billions of neutrinos going out of the nuclear reactor of Hanford every second. This was the "Poltergheist project". In 1956, they discover the neutrino at the Savannah River nuclear plant.

Frederick Reines is born in 1918, in Paterson, New Jersey. He studies at the Hoboken Institute of Technology, New Jersey, and receives his PhD in 1944, in New York university. From 1944 until 1959, he is employed at the Los Alamos laboratory and spends some years hunting the neutrino particle, which he captured in 1953, and definitely in 1956, with the help of Clyde Cowan. Until 1966, he is professor and director at the physics department of "Case Institute of Technology". He works since 1966 at the physics and astronomy department of the California university. F. Reines passed away on 26 August 1998. SuperKamiokande (Irvine) made a nice page about him.


The Homestake experiment, South Dakota, was conceived by Ray Davis in 1967 and was a pioneering experiment in the solar neutrinos detection. It is running since 27 years with more than 600 tons of chlorine industrial solvent.


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 electron and two neutrinos: this is an other difference between muon and electron. Muon represents the second lepton family. Pontecorvo tried also to detect the neutrino, to study oscillations and to measure its mass.

Bruno Pontecarvo is born on 22nd of August 1913, in Marina di Pisa. He studies in Roma where he gets his PhD. He works with Fermi during the 30's but, facing italian fascism, he must escape to France, from where he must once more escape in 1940. He works in Canada, then in England from 1948. In 1950, he disappears. He is recognized 5 years later in Russia, where he has decided to spend the rest of his life, with his family. He dies on 24th of September 1993 in Dubna, Russia.


Ettore Majorana is born in Sicilia in 1906. In 1933, he is a student of Enrico Fermi and then works with him. He elaborates in 1937 a symmetrical theory of weak interaction, where the neutrino is identical to the anti-neutrino. One year later, he disappears under mysterious conditions. Nowadays, physicists still don't know if neutrinos are of "normal" type (Dirac neutrinos) or of "Majorana" type.

Tsung Dao LEE and Chen Ning YANG

Those two theoretical physicists predicted in 1956 the violation of parity symetry in weak interactions: this was confirmed some months later by the Cobalt 60 experiment of Ambler, Hayward, Hobbes, Hudson and Wu Lee and Yang received for that the physics Nobel price 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 is born in Shanghai in 1926. He comes to USA in 1946 to pursue his studies at the Chicago university, where he receives his PhD under the direction of Enrico Fermi. He teaches at Chicago university, then at Berkeley university and at Princeton university, before joining Columbia university in 1953. He studies and contributes greatly to the knowledge about weak interaction (parity violation in 1957, neutrino nu_mu in 1960, spontaneous CP symetry breaking in 1974...). Since 1976, he contributed in general relativity, field theory on random net and high temperature supra-conductors.


Jack Steinberger is born in 1921, in Bad Kissingen, Germany. In 1934, he must run away from Nazism and pursues his studies of chemistry in the Illinois Institute of Technology, USA. In 1942, he joins the american army and is affected to the radar stations There, he learns physics and, in 1945, he follows the course of Fermi at the Chicago university, where he receives his PhD. In 1948, he teaches in Princeton university, then Berkeley in California, finally in Columbia university from 1950 until 1968, where he participates to bubble chambers experiments and to the experiment which discovers the neutrino nu_mu, in 1962. He then goes to CERN until 1986, where he becomes associate professor of Pisa university. In 1988, he shares the Physics Nobel price with Schwartz and Lederman for their discovery of the numu.


Leon Lederman is born on 15th of July 1922, in New York. He pursues his studies until 1943, when he joins the american army. In 1946, he follows the course at the Columbia university where he receives his PhD in 1951. In 1958, he becomes professor and go for a sabbatic year at CERN. Coming back, he associates to Steinberger and Schwartz in the experiment which gives him the physics Nobel price in 1988. From 1961 until 1978, he leads the Brookhaven laboratory, where he participates to the discovery of the b quark (bottom). In 1979, he becomes director of Fermilab and leads the construction of the Tevatron (which allows today to the CDF experiment to give evidence to the most heavy particle: the top quark). In 1989, he joins the Chicago university and creates in 1995, at Fermilab, a scientific educative center, which is a model of scientific teaching, which triggered G. Charpak for the experience la "main a la pate"..


Melvin Schwartz is born in 1932. He studies at Columbia university and receives his PhD in 1958, after a two years work at Brookhaven laboratory. In 1963, he becomes 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 becomes professor at Stanford university. He then funds in 1983 a company of computing network, which he leaves in 1991 to return as a professor to Columbia university, where he works on quarks-gluons plasmas.

Martin PERL

Martin Perl discovered in 1977 the tau particle, the most heavy lepton and the partner of the tau neutrino (this neutrino has still not been observed).

Martin Perl is born in 1927. He studies chemistry in Brooklyn Polytechnic Institute and receives his PhD in Columbia university in 1961. After teaching some time at the Michigan university, he joins in 1963 the Stanford Accelerator laboratory, where he spends 12 years hunting for leptons. In 1975, thanks to the new collision machine SPEAR, he discovers the tau lepton, but his discovery is not confirmed by others experiments among the world. He spends may be the four most awful years of his life until 1979 where the tau is seen once again. Martin Perl works now at the Stanford university laboratory.


During more than 30 years, John Bahcall studied the sun, under many details. The present standard solar model, on which lays the predictions of solar neutrinos flux has a great debt to his works. He also participated to the first experiments trying to detect solar neutrinos with Ray Davis.

Born on 30th of December 1934 in Louisiana, he studies in Harvard and receives his PhD in 1961. After a stay at the Indiana university, then in California Institute of Technology (CalTech), he becomes professor at the Princeton university in 1971.

Chien Shiung WU

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".

And many others...

Many physicists since Pauli in 1930 and Reines in 1953 have had great interest in the strange neutrino. Impossible to give all the names. L. Alvarez, for instance, contributed to clarify the mystery in the years 50's and 60's.
All the names, this is finally all the physicists who work now on the neutrino mass measurement, on the neutrinos oscillations, or observe the neutrinos coming from the sky, and, beyond, all those who put one day their finger in the fascinating story of weak interactions.

A special address to a contemporary physicist, Michel Spiro, who has observed with precision the weak interactions and then interested in solar neutrinos as well as brawn dwarfs (MACHOs). Beyond Michel Spiro, I would like to thanks all the GALLEX collaboration for its marvellous result about this mystery of solar neutrinos.

Michel Spiro is born in 1946. He studies in Paris and enters the Polytechnic School in 1966. In 1968, he is in the street. But physics catches him back and he enters in CEA, at the Nuclear Physics department of Saclay. He participates then actively to the UA1 experiment, started in 1977 and which, under the lead of Carlo Rubbia, discovers in 1983 the W and Z bosons. In 1985, neutrinos attract him and he participates to the GALLEX experiment, which ten years later, gives an important and precise result on the measurement of solar neutrinos flux. From neutrinos to dark matter there is only one step, that he does in 1990 to generate the EROS experiment, looking for dark objects around our galaxy, sorts of unlighted suns called "braun dwarfs", which are candidate to the dark matter like the neutrinos. Finally, in 1995, he is an accomplice of M. Cribier and D. Vignaud for writing "La lumiere des Neutrinos", a book in which those Web pages found many informations.

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Last update: 26/06/1999 :
Didier Verkindt