1 CERN – from birth to success 1 Herwig Schopper CERN and University of Hamburg A historical review is given of the development of CERN from its foundation to the present from a personal view of the author. Keywords: International organisation, accelerators, colliders, detectors, management. 1.CERN – a unique organization In each volume of RAST an article entitled “person of the volume” is published describing a large laboratory shaped largely by that person. When I was asked to write an article about CERN it was clear that this was impossible since so many personalities have played an essential role over the more than 50 years of CERN’s history, from its establishment to the most recent successes. Indeed there has always been a smooth transition from one Director General to the next, while project leaders have successively passed his tasks on smoothly to their successors. This is the way of CERN, whose international nature has meant that the Organization has had to accommodate a range of approaches, traditions and languages right from the start.1 From its very beginning CERN was a unique organisation based on two quite different initiatives. European physicists started the first initiative as early as 1946. They realized that competition with the USA was only possible if European countries2 joined forces. The first discussions were launched in the framework of UNESCO by Eduardo Amaldi from Italy3, the two French physicists Pierre Auger and Lew Kowarski and the American, Isidor Rabi. A second, and rather independent, initiative that is much less well known was that of the Swiss writer Denis de Rougemont who had spent the war at Princeton where he had met and interviewed Einstein. After his return to Europe in 1948 de Rougemont became, together with Raoul Dautry (‘administrateur- general’ of the French Commissariat a l'Energie Atomique CEA) and other far-sighted diplomats and administrators, one of the driving forces of the 'European Movement', which resulted in the creation of the Centre Européen de la Culture at Lausanne in 1950. The objective was to build bridges between people who had been at war and an international scientific laboratory was considered to be the best tool to bring scientists, administrators and politicians together for peaceful work – ‘science for peace’. The two initiatives were amalgamated into a proposal to the UNESCO General Conference at Florence in June 1950 and it was Isidor Rabi who, inspired by the foundation of Brookhaven National Laboratory, formulated the decisive motion that was eventually submitted and accepted by UNESCO. When I invited Rabi to give a speech at the 30th anniversary of CERN in 1984, he said: ‘Europe had been the scene of violent wars…for 200 years. Now we have something new in the founding of CERN, namely Europe has gotten together, in the cause of science..…So I think it is most important for CERN to continue and be the symbol and the driving force of a possible unity of Europe… I hope that the scientists at CERN will remember that they have other duties than exploring further into particle physics. They represent the combination of centuries of investigation and study… to show the power of human spirit. So I appeal to them not to consider themselves as technicians …but... as guardians of this flame of European unity so 1 Herwig Schopper, CERN, CH-1211 Geneva 23 [email protected] 2 that Europe can help preserve the peace of the world’4. Thus CERN became the only international organisation2 that has two main objectives: to promote science and to contribute to peace. 2. Difficult birth After the principal decision of UNESCO, two groups, one of scientists and another of administrators and diplomats, started discussions on the specific structure and objectives of the new organization. After lengthy discussions reflecting serious differences of opinion concerning the future character of the laboratory, among the diplomats as well as among the scientists, they proposed that a temporary organization to be created with the aim of constructing the biggest proton synchrotron in the world with an energy higher than that of the 6 GeV Bevatron in the USA. In June 1953 a formal convention was Figure 1 Start of excavation at the Meyrin site in 1954 agreed for the preliminary organization, which was called the ‘Conseil Européen pour la Recherche Nuclaire’ (European Council for Nuclear Research) CERN, a name which became a trade mark of quality and is still maintained today, although a subtitle was later added: ‘European Laboratory for Particle Physics’. The CERN convention entered into force on 29 September 1954 after 12 countries (Belgium, Denmark, France, Germany, Greece, Italy, Netherlands, Norway, Sweden, Switzerland, United Kingdom and Yugoslavia, followed soon by Austria and later by Spain and Portugal) had sent documents of ratification to UNESCO. A group of historians that has described in detail the foundation of CERN came to the conclusion that “it succeeded because the entire project remained in the hands of scientists”. 5 A major controversial issue remained, however: the choice of a site for the new organization. Several sites were proposed: Geneva in Switzerland, Copenhagen in Denmark, Arnhem in the Netherlands and a site near Paris. After long bargaining, Geneva was selected because it is in a small country and has an international environment. France had hoped to have good chances in view of the strong involvement of French scientists in the early discussions. They agreed finally to the compromise, not least because Geneva is French speaking. The convention is a rather short document, wisely leaving a lot Figure 2 F.Block, first Director-General of room for interpretation. New Member States required a laying the foundation stone watched unanimous vote in Council. They should come from Europe, but by M.Petitpierre, President of the the definition of Europe was left rather vague. Consequently, Swiss Confederation and following a sustained policy of openness, CERN has 2 The only other international organization with these two aims is the synchrotron laboratory SESAME in Jordan. When I was involved in its establishment in 2004, also under the auspices of UNESCO in a similar way to CERN, I copied the CERN convention for that of SESAME. 3 gradually developed from a European laboratory into a laboratory for the world. At present CERN has 20 Member States, with Romania a candidate for succession and five others including Israel, Cyprus and Turkey on their way to becoming Members. Two conditions of the convention are still valid today: contributions are proportional to the GNP of the Member States (with a cap of 25 %) and they have to be paid in Swiss Francs. The first makes it difficult for countries like the USA or Russia to become a Member since they would dominate the organization. Recently the status of Associate Member has been created which will allow a stronger formal relationship with these and other countries. Scientific cooperation was never hindered by formal arguments. One of the founding principles was that any scientist of the world is welcome to participate in the CERN program provided that his or her participation improves the quality of the program. 3. The first steps to success After the provisional foundation of CERN, Eduardo Amaldi who had played already a major role as part of a group of experts, was appointed Secretary General in 1952, a function that later became known as Director General. At the same time the Norwegian Odd Dahl became chairman of the Proton Synchrotron (PS) group, a group of about a dozen of people with very little experience in accelerator technology, but sufficiently courageous to start the construction of the largest synchrotron in the world. In summer 1952 some of them visited the USA and at Brookhaven they got to know to their big surprise a new idea for focusing particle beams, alternating gradient or strong focusing. Dahl convinced the CERN Council that the PS should be based on the strong focusing principle. However, Dahl withdrew from CERN and was replaced by John B. Adams who in the coming decades was to play a major role in the development of CERN. The strong focusing principle allowed the beam size to be reduced by an order of magnitude, and consequently the scale of magnets providing the guiding field. Hence a more ambitious machine could be envisaged for the original price tag of about 100 Million Swiss Francs, a lot of money in those days, and Adams proposed a PS with a maximum energy of 25 GeV, extendable to 28 GeV. The PS group, which grew to about 180 members, was faced with the enormous task of building a completely new machine on a green field site at the outskirts of Geneva. After 5 years of construction and some difficult weeks of tests, the acceleration to 25 GeV was achieved for the first time on 24 November 1959. As planned, the PS had become the highest energy accelerator in the world, a success that was announced by Cornelis Bakker who had followed the first Director General of CERN, Felix Bloch. Thanks to the PS, the validity of the strong focusing principle was proven, although no real understanding of the beam behaviour during acceleration had yet been achieved. The instruments for beam diagnostics and control were infinitely primitive compared to the sophisticated instrumentation of today’s synchrotrons. The PS has undergone various upgrade and extension programs that continue to the present day. They include the acceleration of antiprotons, electrons, positrons and heavy ions. This is because the PS has served as injector for a string of later machines: the ISR, antiproton accumulators, the SPS, LEP and finally the LHC. Thus the PS has become the most versatile part of CERN’s installations.