The journal Physical Review receives the paper Antineutrons Produced from Antiprotons in Charge-Exchange Collisions by a second team working at the Bevatron – Bruce Cork, Glen Lambertson, Oreste Piccione and William Wenzel. The paper – which announces the discovery of the antineutron – is published in the issue dated November 1956.
Safety is top priority in any scientific research laboratory, and fire prevention was an important issue from the earliest days of CERN. The newly constructed buildings were fitted with smoke detectors, and voluntary fire brigades and first aid teams were set up among staff members.
On 14 June 1956 a telegram from Frederick Reines and Clyde Cowan informed Wolfgang Pauli that neutrinos had been detected from fission fragments - nearly 26 years after Pauli first postulated the neutral particle as a solution to the missing energy during beta decay.
When CERN was just over a year old, the Scientific Policy Committee was asked its opinion “as to the advisability of purchasing [an] electronic computer”. Lew Kowarski thought we should buy one, and his proposal (CERN/SPC/13) makes fascinating reading. He gives an overview of the current state of the market and outlines some issues to be considered. These included costs and staffing requirements, but also the fact that physicists were unlikely to bother learning to use this new machine unless it was clear that the effort was worthwhile!
A paper titled "Observation of antiprotons," by Owen Chamberlain, Emilio Segrè, Clyde Wiegand, and Thomas Ypsilantis, members of what was then the Radiation Laboratory of the University of California at Berkeley in the US, appeared in the 1 November 1955 issue of Physical Review Letters. It announced the discovery of a new subatomic particle, identical in every way to the proton – except its electrical charge was negative instead of positive.
A month before the paper appeared, The New York Times had put the news on the front page:
Voting for the Committee members of CERN’s newly formed Staff Association closed at midnight on 11 July 1955; Messrs J.A. Giebel, K. Johnson, J. P. Stroot, E. Zaccheroni, J. Ball, R. Siegfried, Miss C. de Mol and Miss A. Schubert were duly elected, with 177 votes cast.
“On this tenth day of June, one thousand nine hundred and fifty five, on ground generously given by the Republic and Canton of Geneva, was laid the foundation stone of the buildings of the headquarters and the laboratories of the European Organization for Nuclear Research, the first European institution devoted to co-operative research for the advancement of pure science”
“Wholeheartedly agree – the sooner the better!” – CERN’s personnel officer was enthusiastic about the idea of creating a Staff Association in 1955. The Director of Administration, Sam Dakin, was similarly encouraging, writing to the Director-General: “Very often I am conscious that in attempting to judge the needs and wishes of the staff, we have to rely on ordinary gossip and that for official comments we have only those of Divisional Directors who may not always accurately know or represent the feeling of their staff.
In his seasonal greetings to CERN’s Director-General and staff, the President of the CERN Council acknowledged the difficulties faced by a young organization and the devotion shown by all those involved in overcoming them.
Has it ever struck you as odd that the initials CERN refer to an organization that ceased to exist when the current organization was created? If so, you’re not alone.
When the CERN Convention was signed in 1953, it was assumed that the long-awaited European laboratory would soon become a reality. But ratification formalities took longer than expected. Meanwhile work on the ground was forging ahead, so it was a relief for the interim governors when the new CERN Council finally took office some 15 months later.
The CERN convention was signed in 1953 by the 12 founding states Belgium, Denmark, France, the Federal Republic of Germany, Greece, Italy, the Netherlands, Norway, Sweden, Switzerland, the United Kingdom and Yugoslavia, and entered into force on 29 September 1954.
At the sixth session of the CERN Council, which took place in Paris from 29 June - 1 July 1953, the convention establishing the organization was signed, subject to ratification, by 12 states. The convention was gradually ratified by the 12 founding Member States: Belgium, Denmark, France, the Federal Republic of Germany, Greece, Italy, the Netherlands, Norway, Sweden, Switzerland, the United Kingdom, and Yugoslavia. On 29 September 1954, following ratification by France and Germany, the European Organization for Nuclear Research officially came into being.
A telegram from Jean Mussard informed Edoardo Amaldi (Secretary-General of the provisional CERN) that the CERN Convention had finally come into force on 29 September, when France and Germany deposited their instruments of ratification at UNESCO House in Paris.
A historic moment passed almost unnoticed on 17 May 1954, as the first excavation work started in the Meyrin countryside and construction of CERN began. Future events of this kind were celebrated with speeches, press coverage and parties, but this was a quiet and purely unofficial ceremony.
The Bevatron in 1958 (Image: Lawrence Berkeley National Laboratory)
In 1954, Ernest Lawrence oversaw the building of a proton accelerator called the Bevatron at the radiation laboratory in Berkeley, California. The machine's name comes from BeV, the symbol used at the time for "billion electronvolt", or 109 electronvolts. We now call this unit the gigaelectronvolt, symbol GeV – BeV is no longer used. The Bevatron was designed to collide protons at 6.2 GeV, the expected optimum energy for creating antiprotons.
On 17 May 1954, the first shovel of earth was dug on the Meyrin site in Switzerland under the eyes of Geneva officials and members of CERN staff.
Even before the official creation of CERN in 1954, staff began to settle into temporary offices around Geneva. On 5 October 1953 part of the PS (Proton Synchrotron) Group, including Frank Goward, John Adams, Mervyn Hine, John and Hildred Blewett, Kjell Johnsen and Edouard Regenstreif, arrived to take up residence in offices that had been made available in the University of Geneva’s Institute of Physics .
After long months of negotiation - success! The work of the provisional Council responsible for planning the new international laboratory for nuclear physics reached a successful conclusion on 1 July 1953 with the signature of the CERN Convention.
The detector used for the first observations of atmospheric-Cherenkov radiation: a dustbin with a small parabolic mirror and phototube (Image: G Hallewell)
Geneva was selected as the site for the CERN Laboratory at the third session of the provisional council in 1952. This selection successfully passed a referendum in the canton of Geneva in June 1953 by 16,539 votes to 7332.
Too often trip reports are just boring administrative documents, but this one caused a radical rethink of the design for CERN’s Proton Synchrotron. Suddenly a relatively straightforward engineering challenge became a development project for an untested idea.
“We have just signed the Agreement which constitutes the official birth of the project you fathered at Florence. Mother and child are doing well, and the doctors send you their greetings.” This was the message sent to Isidor Rabi on 15 Feb 1952 by the signatories of an agreement establishing the provisional European Council for Nuclear Research.
William H. Sweet and Gordon L. Brownell at Massachusetts General Hospital in Boston suggested using the radiation emitted by positron annihilation to improve the quality of brain images by increasing sensitivity and resolution. They published a description of the first positron-imaging device to record three-dimensional data of the brain in their 1953 paper Localization of brain tumors with positron emitters in Nucleonics XI. This was the beginning of positron emission tomography.
Danish physicists Otto Kofoed-Hansen and Karl-Ove Nielsen, working at the Institute for Theoretical Physics at the University of Copenhagen, are first to demonstrate how to produce radioisotopes with an on-line technique. In a paper entitled Short-lived Krypton isotopes and their daughter substances Kofoed-Hansen and Nielsen demonstrate the feasibility of on-line production of short-lived radioactive isotopes.
At the end of the Second World War, European science was no longer world-class. Following the example of international organizations, a handful of visionary scientists imagined creating a European atomic physics laboratory. Raoul Dautry, Pierre Auger and Lew Kowarski in France, Edoardo Amaldi in Italy and Niels Bohr in Denmark were among these pioneers. Such a laboratory would not only unite European scientists but also allow them to share the increasing costs of nuclear physics facilities.
Stereoscopic photographs showing an unusual fork (a b) in the gas. The direction of the magnetic field is such that a positive particle coming downwards is deviated in an anticlockwise direction (Image: Nature)
Groups led by Bruno Rossi in the USA and Georgi Zatsepin in Russia started experiments on the structure of Auger showers. These researchers constructed the first arrays of correlated detectors to detect air showers.
Wolfgang Pauli was awarded the 1945 Nobel prize in physics for his Exclusion Principle. When he received the telegram from Arne Westgren (15 November 1945) Pauli was working at the Institute for Advanced Study in Princeton, having left Europe for the USA during the Second World War. Pauli was the first resident member of the Institute to receive a Nobel prize; his colleagues greeted it with great enthusiasm and the Director organised an official ceremony.
Pierre Auger, who had positioned particle detectors high in the Alps, noticed that two detectors located many metres apart both signaled the arrival of particles at exactly the same time. A systematic investigation of the showers showed coincidences between counters separated horizontally by as far as 75 metres. While the counting rate dropped sharply in going from 10 centimetres to 10 metres, the rate decreased slowly at larger distances.
The muon was discovered as a constituent of cosmic-ray particle “showers” in 1936 by the American physicists Carl D. Anderson and Seth Neddermeyer.
The muon was discovered as a constituent of cosmic-ray particle “showers” in 1936 by the American physicists Carl D. Anderson and Seth Neddermeyer.
Read the paper:"Note on the nature of cosmic-ray particles"
Wolfgang Pauli is seen here with his former teacher Arnold Sommerfeld attending a conference on the electron theory of metals in Geneva, 15–18 October 1934. The conference proceedings don’t mention any leisure activities, but these included a cable car trip up the nearby Salève mountain to enjoy views of Geneva town, the lake and the Alps. The Salève is in France and Sommerfeld had no French visa, so conference organiser Jean Weiglé obligingly smuggled him up to join the others in his car.
Bruno Rossi (Image: Wikimedia Commons)
The discovery was confirmed soon after by Occhialini and Blacket, who published Some photographs of the tracks of penetrating radiation in the journal Proceedings of the Royal Society A. Anderson's observations proved the existence of the antiparticles predicted by Dirac. For discovering the positron, Anderson shared the 1936 Nobel prize in physics with Victor Hess.
Photograph from Occhialini and Blacket’s paper showing tracks of radiation (Image: Blackett, P.M.S., & Occhialini, G.P.S., Royal Society of London Proceedings Series A 139 (1933) 699)
In 1932 Carl Anderson, a young professor at the California Institute of Technology in the US, was studying showers of cosmic particles in a cloud chamber and saw a track left by "something positively charged, and with the same mass as an electron". After nearly a year of effort and observation, he decided the tracks were actually antielectrons, each produced alongside an electron from the impact of cosmic rays in the cloud chamber.
Among the scientific documents in CERN’s Wolfgang Pauli Archive is a rather unusual item – a copy of the script parodying Goethe’s Faust performed at the Niels Bohr Institute conference, 3-13 April 1932 (exact date of performance not known). Written mostly by Max Delbrück, and decorated with caricatures of the protagonists, the skit features Pauli (Mephistopheles) trying to sell the idea of the neutrino (Gretchen) to a sceptical Paul Ehrenfest (Faust)!
Paul Dirac published a paper mathematically predicting the existence of an antielectron that would have the same mass as an electron but the opposite charge. The two particles would mutually annihilate upon interaction.
Bothe and Kolhorster’s experiment (Image: L. Bonolis, American Journal of Physics, 79 (2011), 1133. Reproduced under Creative Commons license)
While studying cosmic rays in a Wilson cloud chamber, the Soviet academic Dimitri Skobeltsyn noticed something unexpected among the tracks left by high-energy charged particles. Some particles would act like electrons but curve the opposite way in a magnetic field. In an independent experiment that same year, Caltech graduate student Chung-Yao Chao observed the same phenomenon. The results were inconclusive, and both scientists disregarded the anomaly.
Robert Millikan originally set about to disprove Hess and Kolhörster’s discovery. He and Ira Sprague reached a height of 1500 m in a balloon over Texas where they recorded a radiation intensity of approximately one quarter of Hess and Kohörster's measurement. The difference was caused by a geomagnetic difference between Texas and Central Europe but was blamed on turnover in the intensity curve at high altitude.
Despite some reservations about his lecturing style, Wolfgang Pauli was appointed professor of theoretical physics at the ETH, Zürich, on 10 January 1928. He started on 1 April at a basic annual salary of 15,000 francs.
In 1928, British physicist Paul Dirac wrote down an equation that combined quantum theory and special relativity to describe the behaviour of an electron moving at a relativistic speed. The equation would allow whole atoms to be treated in a manner consistent with Einstein's relativity theory. Dirac's equation appeared in his paper The quantum theory of the electron, received by the journal Proceedings of the Royal Society A on 2 January 1928. It won Dirac the Nobel prize in physics in 1933.
Using a cloud chamber, Dimitry Skobelsyn took the first photographs of tracks left by cosmic rays. Skobeltsyn was the first to advance the idea of using the registration of recoil electrons (Compton electrons) in a gas-filled Wilson cloud chamber. In his 1927 experiments, Skobeltsyn worked out the momenta of charged particles passing through the chamber from their degree of deflection by a magnetic field.
Wolfgang Pauli, Werner Heisenberg and Enrico Fermi relax on Lake Como during the 1927 International Conference on Physics.
In the 1920s, physicists were trying to apply Planck's concept of energy quanta to the atom and its constituents. By the end of the decade Erwin Schrödinger and Werner Heisenberg had invented the new quantum theory of physics. The Physical Institute of the University of Zürich published Schrödinger's lectures on Wave Mechanics (the first from 27 January 1926) and in 1930 Heisenberg's book The physical principles of the quantum theory appeared.
In October 1918 Wolfgang Pauli left Vienna to study at the University of Munich. His Kollegienbuch gives a glimpse of the lecture courses he followed.
Increase in ionization with height measured by Hess and Kolhörster (Image: Wikimedia Commons)
German physicist Werner Kolhörster took balloon measurements up to a height of 9300 m, confirming Hess’s results for greater heights. His results confirmed unambiguously that an unknown radiation with an extreme penetrating power was causing ionization. The intensity of the radiation was relatively constant, with no day-night or weather-dependent variations.
Hess back from his balloon flight on 7 August 1912 (Image: Wikimedia Commons)
In 1911 and 1912 Austrian physicist Victor Hess made a series of ascents in a balloon to take measurements of radiation in the atmosphere. He was looking for the source of an ionizing radiation that registered on an electroscope – the prevailing theory was that the radiation came from the rocks of the Earth.
Cloud formed on ions due to α-Rays (Image: CTR Wilson Roy, Proceedings of the Royal Society A, Volume 85, Plate 9)
Domenico Pacini making a measurement on 20 October 1910 (Image: Wikimedia Commons)
To measure ionizing radiation away from the earth’s surface, several researchers took to the air in balloon flights in the first decade of the 20th century. One of these pioneers, Albert Gockel, measured the levels of ionizing radiation up to a height of 3000 metres. He concluded that the ionization did not decrease with height and consequently could not have a purely terrestrial origin. He also introduced the term “kosmische Strahlung” – cosmic radiation.
The original Wulf electroscope (Image: Wikimedia Commons)
In 1909 Theodor Wulf, a Jesuit priest, designed and built a more sensitive and more transportable electrometer than the gold leaf electroscopes. He measured the ionization of the air in various locations in Germany, Holland and Belgium, concluding that his results were consistent with the hypothesis that the penetrating radiation was caused by radioactive substances in the upper layers of the Earth’s crust.
On 30 June 1905 the German physics journal Annalen der Physik published a paper by a young patent clerk called Albert Einstein. The paper, Zur Elektrodynamik bewegter Körper, (On the Electrodynamics of Moving Bodies) set out Einstein's theory of Special Relativity, which explains the relationship between space and time – and between energy and mass – in the famous equation E=mc2. The paper used Planck's concept of energy quanta to describe how light travels through space.
Bertha Camilla Schütz (known as Maria) was born in Vienna in 1878. A writer and journalist, she followed in her father’s footsteps as collaborator on the Neue Freie Presse, writing theatre reviews and historical essays. In 1899 she married Wolf Pauli and their first child was born on 25 April 1900. Wolfgang junior, seen here at the age of 20 months, grew up to be a Nobel prizewinning physicist, and his sister Hertha (1906-1973) became an actress and writer.
In studying electrical conduction through air in 1899, Julius Elster and Hans Geitel designed a key experiment where they found that surrounding a gold leaf electroscope with a thick metal box would decrease its spontaneous discharge. From this observation, they concluded that the discharge was due to highly penetrating ionizing agents outside of the container. In a similar experiment at about the same time, Charles Thomson Rees Wilson in Cambridge came to the same conclusion.
The first evidence for radioactivity – images formed by Becquerel’s uranium salts (Image: Wikimedia Commons)
In 1785, the French physicist Charles Augustin de Coulomb made three reports on electricity and magnetism to France’s Royal Academy of Sciences. His third paper described an experiment with a torsion balance, which showed that the device would spontaneously discharge due to the action of the air rather than defective insulation.