CHAPTER 1

CERN from the mid-1960s to the late 1970s

John KRIGE

Contents

1.1 Some preliminaries 7 1.2 The growth in the user population 13 1.3 Machines and beams 18 1.3.1 The Proton Synchrotron 19 1.3.2 The Synchro-Cyclotron 22 1.3.3 The Intersecting Storage Rings 23 1.4 Detectors 26 1.5 The member states 29 Notes 35

(CRHST, CNRS and Cite des Sciences et de I'lndustrie, 75930 Paris, France)

3 Before surveying the years in the Ufe of CERN covered by this book, let us pause for a moment to consider the periodization itself. How should one dissect this organization- dedicated-to-science? What moments is the historian to elevate to the status of 'turning points', so giving shape to the narrative but also inevitably imposing a particular rhythm and logic on it? There is no one answer to these questions, no one criterion for making one's cuts, no one way to transform a story into a history. The choice that we made - if one can call it a choice, for it was initially made only half-consciously - was to organize the history of CERN around the decisions to equip it with its major accelerators. Thus volume I took us up to 1954, when the organization was officially established with its 600 MeV synchro-cyclotron and its 28 GeV proton synchrotron ^ Volume II took us up to 1965 when it was decided that CERN should be equipped with a proton-proton collider, the Intersecting Storage Rings to be followed as soon as possible by a major fixed-target machine, formally adopted in fact only six years later (the 300 GeV Super Proton Syn• chrotron)^. This volume covers the period up to the late 1970s, precisely so as to include the decision to build a proton-antiproton collider at the SPS and to avoid entering the debate surrounding the decision to build CERN's next major accelerator, a large electron- positron collider. Studies on a LEP machine began in 1976, and the first major design report for an accelerator of circumference 22 km which was cost-optimized on 70 GeV per beam was pubHshed in 1978. In that same year the European high-energy physics com• munity formally adopted a LEP as its next big machine. The debates over its design, ultimate target energy and funding were complex and controversial, and would have drawn us into the 1980s, a period deemed too recent to permit a sober historical analysis when the work on this volume got under way about five years ago. This mode of periodization bears reflection, all the more so since our use of it has never been explicitly questioned by the high-energy physics community itself. Its significance is twofold. Firstly, the kind of physics one can do depends on the kind of machine that one has at one's disposal: its energy, its intensity, and its flexibility are crucial variables in the definition of a research programme. Secondly, machines are expressions of power and prestige: power to shape and to dominate the research frontier, power to compete effec• tively at the world level, power to raise money from governments. At heart then the periodization adopted in these three volumes of CERN's history is one which reflects and reinforces the ambition of the European high-energy physics community, and the science administrators and governments who supported them so reliably, to have the equipment needed to place them among the world leaders in their field of research. If the dates that have structured our narrative are necessarily to be taken as 'turning points' it is in the sense that at that moment another step was taken up the spiral of ever-increasing energy, a decision was taken to build an even more powerful machine. It is this that our history celebrates and legitimates. This choice of timespans is not without interest, far from it, but as we have said it is not the only one possible. We could, for example, have delimited our research using Nobel prizes missed and won (the two neutrinos, the J/psi, the W and the Z...). Or the reigns of the laboratory's successive Directors General (the Weisskopf era, the Gregory era...). Or the national science policies and foreign policies of CERN's member states, most notably Britain, France and Germany (which would have forced us to situate the laboratory in the context of European economic, political and miUtary reconstruction)^. Each of these options imposes its own rhythm and chronology as well as its own set of pertinent questions. No one is all-encompassing, no one of them can give us a 'complete picture' of CERN's history. Indeed no such picture exists; it is rather up to the historian to fabricate a picture out of the materials available - documents, interviews, first hand experience. This picture will necessarily be framed by a variety of implicit and explicit assumptions and questions, assumptions and questions which are specific to the conjuncture in which the work is produced. The characteristics of the period which we have chosen to cover here, bounded as it is by decisions about accelerators, are not easily captured in a few lines. For volume I our task was simple: we described the launch of CERN, how and why a handful of European scientists and science administrators imposed a costly laboratory equipped with machines far bigger than anything ever constructed in Europe on a physics community and on governments which were often sceptical, not to say hostile to the feasibihty and indeed desirabihty of the project. Similarly, for volume II, we quickly settled on a catch-all phrase. The book described the building and the early running of the laboratory: the construction of the machines, the negotiations over the laboratory's internal structure and experiments committee system, the difficulties raised for scientists and governments alike in moving from a period of machine construction to one of exploitation, the sometimes bruising debates with the outside users community over access to the laboratory's facil• ities, the first physics programmes, and the choice of CERN's next generation of accel• erators. Now as we move into the next period, many of these earlier difficulties have been resolved. There were of course moments of great drama: the titanic struggle to have the SPS accepted by governments as CERN's major fixed-target machine for the 1970s, the visitors revolt in the early 1970s, the announcement of weak neutral currents and the disbehef and depression that 'the ISR [had] missed the J/psi and later missed the upsilon'"*, the testing and implementation of the beam-shrinking technique of stochastic cooling. But these moments of drama apart, CERN seems to have 'ticked along' quite smoothly in these years, its global budgets, its equipment, its experimental programmes, and its staff (as well as their experience in managing a major laboratory), expanding steadily. A little story will make the point. In volume II we made much of CERN's un- preparedness for doing physics at 28 GeV, as evidenced typically by its lack of suitable beam transport equipment, a criterion which encapsulated many features of the young CERN: inexperience on the experimental floor, in the directorate and in the Council, the

Notes: p. 35 6 CERNfrom the mid-1960s to the late 1970s relations between physicists and engineers and about what it meant to do physics, the emergence of a number of mandarins each determined to control a part of the physics programme for himself. Indeed when the PS experimental programme got under way early in 1960, CERN had only three beam transport elements of its own. The first beams were made without lenses and with magnets begged or borrowed from various sources. Welding generators were put into service as power supplies and the ordinary town water was used for cooling. Something like a third of the South [experimental] Hall was still a workshop and the North Hall was still being used as an assembly area by the PS Division'. Ten years later there were about 250 beam transport elements at hand for the PS experimental programme, and floorspace had almost quadrupled from 2500m^ to 9000m^. The labo• ratory staff had learnt what it meant to do physics around big machines^. John Adams, who had directed the construction of the PS, surely had the traumas of the early 1960s in mind when he wrote, in 1977, that 'One of the triumphs of the SPS Programme planning [for which he was partly responsible of course] [...] was that the accelerator and the massive detectors were ready at the same time so that experimental research could begin this year without delay'^. In short, in the period covered by this book, CERN had overcome many of its early difficulties and was functioning efficiently as a European organization-dedi- cated-to-science. Seen in this light, there seems to be another kind of logic linking our three volumes of CERN's history. It is the pervasive and pernicious logic of birth, adolescence and adult• hood (what a happy coincidence that we have just three tomes!), each one following on the other and consolidating the 'lessons' learnt before. This spurious continuity, this super• ficial metaphor must be resisted at all costs. For it masks the specificity of different periods in the laboratory's development, the displacements and ruptures which differentiate contexts and practices from one another over time. For example, the political and eco• nomic world in which CERN hved in the late 1960s was totally different from that in the early 1950s when it was established. Experimental practice in high-energy physics in the early 1970s was quite other in complexity and in kind to that just a decade before. To speak of CERN as growing into maturity over the 30 years covered by our histories is to impose a priori an abstract homogeneity on the rich, differentiated texture of the past. Wherein lies the specificity of the period covered by this book? It is, we would suggest, in the way in which CERN was situated, and situated itself, vis-a-vis its outside users and member states' governments. In the late 1950s and early 1960s CERN was thought of as being a leading research laboratory deliberately isolated from the world around it, an ivory tower for a select few whose dominant task was to do high-energy physics. This conception began to change in the late 1960s and early 1970s. Now the outside users and the governments alike increasingly demanded that CERN take their interests into account, respect their needs. The laboratory was allowed to expand, to concentrate (almost) the entire European high-energy physics effort on its site - but on condition that it responded to the demands made by national physics communities and science administrations. For the first decade of its life CERN had traded on the myth of the nuclear and of European reconstruction to create a space in which it was more or less immune to the usual financial Some preliminaries 1 and political constraints of a research laboratory, and was easily able to fend off criticisms from its users about the sometimes arrogant and patronising behaviour of its Senior Staff. This was no longer possible. A new generation of physicists, many of them trained on big equipment in the US during the sixties, moved to positions of prominence in the field and were simply not prepared to be regarded as less able than the inhouse CERN staff. The member states, squeezed by economic recession, by fears regarding a supposed 'techno• logical gap' which had opened between the two sides of the Atlantic, and by the demands for funding from other areas of science and technology, notably space, were simply not prepared to pour money into CERN without seeing some direct benefits for their national research efforts and their industry'^. From being a privileged laboratory having a high degree of autonomy CERN was predominantly seen, in the late 1960s and 1970s, as a research faciUty jointly owned by the European high-energy physics community and its governments, and accountable to them. This leitmotif, rather than a summary of the contents of each chapter, has informed the selection of material for this introduction. It is based almost exclusively on the chapters in this book and on CERN Annual Reports (or documents of similar status) so as to maintain a uniform level of analysis. In adopting this approach, which is obviously se• lective, we hope to capture something of the transformation in the character of the lab• oratory during this time. That character is sometimes elusive and difficult to pin down behind the superficial continuities, the efficient organization, the onward and upward expansion and growth. But it is surely there, its presence revealed by a number of events which, collectively, attest to a new conception of this phenomenon that was the CERN of the late 1960s and the seventies^.

1.1 Some preliminaries

Before getting under way we need to provide some basic information about CERN in our period which will be useful, not only for the argument developed here, but throughout the entire volume. The period covered includes the reigns of four Directors General, Bernard Gregory (1966-1970), Williband Jentschke and John Adams (1971-1975), when CERN was mo• mentarily spUt into two laboratories (cf. below), and John Adams and Leon Van Hove (1976-1980), the former baptized the Executive Director General, the latter the Research Director General. These nominations merit two quick comments. Firstly, in the first decade of CERN's life a major effort had been made to attract a physicist of high prestige, who had spent a good deal of time in the United States, to head the laboratory, both to ensure the international reputation of the new research centre and to reverse the 'brain drain'. Hence the choice, first of FeUx Bloch, and then of Victor Weisskopf (with CorneUs Bakker and John Adams sandwiched between them). This cri• terion was no longer dominant. Of course the CERN member states still wanted people of renown and influence in their own countries to fill this highly important post. But it

Notes: p. 36 8 CERNfrom the mid-1960s to the late 1970s

sufficed that they were respected nationally and internationally and, above all, that they had the skills appropriate to the phase the laboratory was passing through. This phase was characterized essentially in terms of major heavy equipment programmes. Thus Bernard Gregory, senior Polytechnicien with an extensive experience with bubble chambers, the first chairman of CERN's Track Chamber Committee in 1960, and director of research under Weisskopf, was chosen to take over from the latter for the second half of the sixties precisely when the bubble chamber technique was blossoming at CERN and when on• going contact was essential with the scientists, engineers, officials and industries in France and in Germany who were constructing the next two big bubble chambers to be installed at CERN, the 'French' heavy liquid chamber Gargamelle and the CERN-Franco-German hydrogen chamber BEBC (Big European Bubble Chamber). Gregory was followed by Jentschke and by Adams. The former was a founder of the Deutsches Elektronen-Syn- chrotron (DESY) laboratory in Hamburg estabUshed in 1959, and chairman of its first board of directors, member of the German CERN delegation from 1964 to 1967, then first chairman of the ISR experiments committee in 1968, and the man chosen to take over the laboratory in the year that the Intersecting Storage Rings were first available for physics. John Adams, the constructor of the PS, called back to CERN to save the Super Proton Synchrotron project, was temporarily granted his own division, but when the member states finally agreed to build the SPS they kept their promise and established a second laboratory parallel to the first with Adams as DG. This system of two DGs was main• tained once the machine was completed. The two laboratories were fused into one in 1976, the year the SPS reached its design energy, John Adams was kept on as Executive Director General of CERN, and he was now twinned with Leon Van Hove, theoretical physicist of high repute who had had a loftgstanding relationship with the TH division at CERN, and who was to be responsible for the laboratory's research programme. When CERN's first DG was appointed early in the 1950s there was a turgid debate over the need to have a laboratory head who was knowledgeable about accelerators but someone, too, who was able to lead the scientific programme and create a 'scientific atmosphere' on a laboratory site dominated by bulldozers and big equipment^. This kind of argument probably played a role again in 1975 when the Council accepted to appoint two DGs. But the heart of the matter was surely Adams' ambition, and his determination to maintain control over the life of the laboratory, and 'his' SPS machine in particular. Kjell Johnsen, who had led the construction of the ISR, had benefitted enormously from the institutional and financial autonomy allowed him as head of a 'supplementary pro• gramme' having its own distinct budget. But he had always remained a senior member of management within the existing CERN structure. John Adams demanded and got more. The Council recalled him in December 1968, 'the intention being to appoint him Director- General of the new European High-Energy Laboratory once its construction has been officially approved'^^. At the time it was thought that the SPS would be built elsewhere than in Geneva. When Adams showed that it would be technologically and financially interesting to use the PS as an injector for the SPS - so breaking a deadlock between governments over where to put the new accelerator - the Council had no choice but to give Some preliminaries 9 him a second laboratory at CERN (Laboratory II) during the construction phase of the big machine^ ^ His competence, authority, prestige and charisma ensured that he retained this office even after the machine was built, and the two laboratories were fused again into one. The decision to set up two parallel laboratories was the only really significant change to the internal structure of CERN in the Gregory and Jentschke-Adams eras. Gregory's main innovation was to group the existing divisions at CERN into a number of departments, so inserting another layer of hierarchy between the DG and the division leaders and opening up another set of top-level posts to the CERN Senior Staff (although sometimes the department head and the division leader were the same person). This structure was also used to create new divisions for relatively short-lived well-defined projects. Typically the construction of an 800 MeV booster for the PS was asssigned to the SI (Synchrotron Injector) division inside the Proton Synchrotron Department. This division existed from 1968 to 1972, it was headed by Giorgio Brianti and its total staff complement never exceeded 100 persons. The Adams-Van Hove regime made a number of important changes to the CERN organigramme. They abolished the departmental structure, and established a directorate of half-a-dozen members who reported directly to them. They also set up a research board (chaired by Van Hove) and an executive board (chaired by Adams) in which the direc• torate, the appropriate division leaders and (in the case of the research board) the chairs of the experiments committees could consult regularly. The divisions concerned with ex• perimental equipment were also totally reorganized. The long-standing spUt based on kind of technique (bubble chambers or electronic) was done away with^^. In its place two new divisions were created. Experimental Physics Facilities and Experimental Physics. EPF was responsible for all heavy equipment required for experimentation on the CERN site and, in the view of the Executive DG, was similar to the accelerator divisions at CERN in terms of the Icind of work carried out and the responsibiUties involved'^^. EP grouped together the experimental physics community, including the outside users, and was the biggest division by far at CERN: 1780 people at the end of 1976, over 1200 of them non- CERN staff. During the first decade covered in this volume the experiments committee system, like the organigramme, was barely changed. In the early 1960s the structure was organized by experimental technique, and there were three main committees dealing respectively with experimental proposals using emulsions (EmC), track chambers (TCC) and electronics detectors (EEC)^"^. Towards the end of 1964 it was proposed to add a nuclear structure committees to deal with the growing interest in studies of that kind at the SC. This committee met only seven times before it was merged, in 1966, with the EmC (reflecting the decreasing importance of emulsions) and renamed the Physics III Committee. These three committees remained in place until 1975. However, they remained limited to work done at the PS and the SC. The experimental programmes on the two new accelerators that were commissioned in our period were not channelled through them but through two new machine-dedicated committees. The first, the ISR experiments committee, was set up

Notes: p. 36 10 CERNfrom the mid-1960s to the late 1970s in 1968 with Jentschke as its chairman as we said a moment ago^^. The second, the SPS experiments committee, was set up in 1973 with Pierre Lehmann as its chairman. In 1976 Adams and Van Hove 'rationalized' the system by abolishing completely a committee system based on experimental technique, and using the machine as the defining criterion: henceforward we have the SCC, the PSC (fused into the PSCC in 1978 to advise on research at both machines), the ISRC and the SPSC. Two other points about the decisionmaking procedures on the experimental programme should be noted. Firstly, in our period the CERN practice was put in place of having a two-tiered system of open meetings with free access for all those interested, followed by a closed meeting where a small group defined their recommendations for the experimental programme^^. Another innovation was that those users with a special interest in a par• ticular piece of heavy equipment, like Gargamelle or the ISOLDE, set up their own 'user's committees'. These committees existed independently of the experiments committees that had been officially sanctioned by the Council and were less formal in constitution. They defined the priorities of those who wanted to experiment with the corresponding facility and funnelled a joint request for beam time and infrastructural support to the appropriate higher-level body (e.g. the Physics III committee for ISOLDE)^'^. Turning now to the Council and its committees, we note (as in Volume II) the internal cohesion of the 'legislative arm' of CERN and the relatively small turnover of a core of senior delegates who had had a long and close association with the laboratory. Indeed many of the CERN 'pioneers' were still engaged with it well into the seventies. Let us limit ourselves to the period up to 1978. Bannier had only left the year before - indeed both Dutch Council representatives, Bannier and Wouthuysen remained unchanged through to 1977! Willems remained in the Council representing Belgium until his death in 1971, when his place was taken by Levaux, who was immediately nominated chairman of the Finance Committee. Amaldi represented Italy until 1972, serving as Council president in 1970 and 1971, years crucial for the resolution of the SPS site problem and when governments gave the green light for the construction of the machine in Geneva. France was represented by Perrin until 1972, when his place was taken by Gregory, recently released from his re• sponsibilities as CERN DG. For Sweden Funke stayed on until 1971, serving as Council president from 1967 to 1969. Chavanne continued to represent Switzerland. Gentner, who had built the SC in the late 1950s and had chaired the Scientific Policy Committee from 1968 to 1971, repesented Germany in the Council from 1971 onwards, and served as Council president from 1972 to 1974, when he handed the responsibiUty over to Leveaux. We shall stop there: the point has surely been made. Throughout our period CERN continued to enjoy the support of a nucleus of senior scientific statesmen and science administrators many of whom had been associated with the laboratory from its very inception, who identified with it and with its success, and who could be counted on to do all that was possible to further its interests in their national state apparatuses^^. Figure 1.1 shows the functional distribution of CERN's expenditure since the start of the organization, at 1974 prices, the last year for which such illuminating diagrams were presented. Some of the categories (all of which include the associated personnel costs) Some preliminaries 11

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Notes: p. 36 12 CERNfrom the mid-1960s to the late 1970s require clarification. The lower two curves refer respectively to the more or less routine expenditure on accelerators, beams, detectors and computers required for the research programme and, secondly, the design, construction or major modifications to such equipment for research purposes that did not require special Council agreement. The category of improvements is dominated by the costs of construction of the ISR up to 1968, while by 1971 the band is shared equally between the machine and items like the con• struction of a booster for the PS (which needed Council approval). The curve marked 'Laboratory IF obviously refers to the SPS construction programme, while the little segment marked '2/3 BEBC is the contribution by the French and German governments to the construction of the big bubble chamber. This figure calls for three comments. First, we see a roughly Unear increase in the overall budget during the first decade of CERN's life, with a sharp change in slope when the ISR and a variety of improvement programmes were approved in the mid-1960s. This new rate of growth was sustained until the peak of the SPS construction programme, touching some 625 MSF, from where it declined gradually. Second notable point: the construction of the SPS was, at the Council's behest, undertaken against a background of gradually falling budgets for the rest of the laboratory's activities (a reduction of 210MSF overall between 1971 and 1978 was called for). Meeting this demand caused endless debates at CERN about possible cuts in the existing experimental programme, but also encouraged the promotion of new projects which were scientifically justifiable and which could help sus• tain the level of the CERN budget until the end of the decade (notably the proton- antiproton coUider)^^. Finally, and related to this point, we note that despite the 'rigorous' regime imposed on CERN, there was a sharp increase in expenditure on major items of experimental equipment in 1971, the investments here remaining constant at a new, sig• nificant level for the rest of the period covered by this graph. In short, the CERN research programme may have been squeezed a little financially in our period, but by and large what strikes one is the ongoing generosity of its fundgivers. The growth in staff numbers confirms the point. In 1966 the CERN staff totalled 2115 persons. This had increased to 2639 by 1968 and to 3092 by 1972: a 50% increase in just four years! The rate of change then decreased, but still the staff numbers climbed to a peak of 3618 persons in summer 1975, a peak from which they then began to decline, albeit gradually. Much of this increase in the early 1970s was of course connected with the construction of the SPS. That said it must also be noted that the staff complement of Laboratory I also increased steadily, if less rapidly than that of Laboratory II, in the early 1970s, reaching 3181 when the global figure touched its highest level in mid-1975.^^ The willingness of governments to support CERN was symptomatic of a number of factors. The field still carried considerable prestige, and competition with the United States was still intense. The big accelerators and detectors promised to contribute to the devel• opment of new technologies and skills in areas like superconductivity which were deemed to be of immense economic importance. High-energy physics also retained a political importance at a global level. In the context of detente in the early 1970s, as exemplified by the ratification of the Salt II nuclear disarmament agreement in 1973, high-energy physics The growth in the user population 13 was specifically identified as the kind of activity that could strengthen international 'se• curity and cooperation', and the physics community once again began discussing the possibiUty of building a world machine^ ^ Couple this with a huge expansion in the size of the European high-energy physics community during the 1960s - it had roughly trebled to about 2000 people by 1972^^-, and one can appreciate that the pressure on governments to continue pouring resources into the fieldwa s intense. CERN benefitted from this. But the support given was no longer unconditional. Returns were sought, not simply by the production of world-class physics results, but also in provision for the needs of outside users and in spin-offs to national industry. The Geneva laboratory became the centre of the European high-energy physics effort in our period but at a certain cost to the au• tonomy of its staff* and of its Council. As we mentioned earlier in this chapter, it is this new role that will structure the remainder of this introductory survey of CERN from the mid- 1960s to the late 1970s.

1.2 The growth in the user population

The community of physicists served by CERN expanded sharply in size, and changed notably in its character during the period we are considering here. The most significant development affecting these reorientations was the increase in the importance of electronic modes of detection, which gradually replaced the bubble chamber as the preferred tech• nique for high-energy physics. This had a direct impact on Ufe at the laboratory for whereas the majority of the 'bubbles' community analyzed their data in their home in• stitutes, physicists using electronic techniques had to spend protracted periods of time on the experimental floor at CERN taking and analyzing data. The number of 'visitors' doing high-energy physics on site in Geneva thus grew rapidly between the mid-1960s and the late 1970s, their numbers further swelled by parallel programmes, hke nuclear studies with the on-Une isotope separator (ISOLDE) at the SC. The effects of this change in experi• mental practice were ampUfied by the decision to build the ISR in 1965, and to build the SPS at CERN in 1971 - a choice of site which was not foreseen originally - , decisions which meant that European high-energy physics became progressively concentrated in one laboratory. National programmes were effectively phased out in Italy, then in France and finally in Great Britain as governments decided that they could not also maintain mean• ingful research programmes at home in a field of research which was far from the market (to use current jargon). Only Germany, with its electron synchrotron laboratory in Hamburg (DESY) could aff*ord to sustain an internationally competitive high-energy physics activity of its own. The CERN staff" and matiagement could do nothing to stop this tide. If in the early 1960s they had tended to regard the laboratory as 'theirs', as a laboratory of which they were the masters, rather hke a national laboratory, by the 1970s it was made clear to them that the visitors deeply resented such attitudes. As the Chairman of ECFA and spokesman for the entire European high-energy physics community was to put it in 1975, the users

Notes: p. 36 14 CERNfrom the mid-1960s to the late 1970s regarded CERN as 'their laboratory' too, as 'the laboratory of us alF; it was not to be 'an ivory tower for a select body of physicists on site'^^. And if these protests carried weight it was because the trend towards increasingly large and complex detectors, both bubble chambers and electronic, demanded financial and human resources beyond those which CERN could muster on its own. Most member states no longer invested heavily in na• tional accelerators, but they did supplement their contributions to CERN by financial and other means (e.g. with computing time) to ensure that their physics communities could play an active role in exploiting the machines available in Geneva. CERN needed the material, financial, and political support of European physicists, science administrators and governments, and had increasingly to bend to their demands. It could no longer perceive itself as a 'host' laboratory opening its doors to 'visitors', with the imbalance of power and privilege that that implied. It was a multinational laboratory with a small permanent research staff serving an ever-growing and influential community of users. It is difficult to track these movements with quantitative precision; considerable data was assembled by CERN and by ECFA on these issues but it was used to answer different questions or to serve different purposes depending on the context in which it was gener• ated. Even if incomplete and not always comparable, it is nevertheless highly indicative of the trends we are discussing, and is presented here in that spirit. Figure 1.2 shows the evolution in the number of scientists on the CERN site between 1966 and 1975. It distinguishes fellows (generally young researchers paid by CERN to spend some time at the Geneva laboratory) from paid and unpaid 'associates', the term which replaced the word 'visitors' in CERN management parlance after the user 'revolt' in the early 1970s^'^. It also charts the number of experimental research staff on the CERN payroll in this period. It has two outstanding features. Firstly, it shows clearly the very slow change in the number of staff on the payroll: it remains roughly steady at between 75 and 90 physicists (of which about half were permanent staff with indefinite contracts, while the remainder stayed at CERN for three to six years). Secondly, it shows the exponential increase in the number of outside users up to about 1973, whereupon the rate of growth slows down. We see then that, if in 1966 there were a little over 350 outside users at CERN at the end of the year, by 1970 this has doubled to about 700, and by 1975 it has more than tripled to about 1150. To put this figure in perspective it is useful to compare it with the situation prevailing at around the same time at CERN's major US rival, the Fermi National Accelerator Lab• oratory, whose machine reached its design energy of 400 GeV in December 1972. Of course we expect the number of outside users here to be far smaller precisely because in the US, unlike Europe, there were several leading high-energy physics laboratories scattered around the country. What is more Fermilab had one machine whereas CERN had three. All the same the difference is striking: in September 1974 the American laboratory esti• mated that there were about 250 users on site taking part in experiments at any time. This number was expected to increase as all of the beam lines were brought into action, but it was doubted that it would go much beyond 350 people, if only for financial reasons^^. In other words, there were about as many outside users at Fermilab in 1975 as there were at The growth in the user population 15

t/5 CC • m>• 1300 z< 1200 h ^^ TOTAL

h

/ UNPAID / ^^ ASSOCIATES / ACTUAL/*^

/ /^^^°n\ ESTIMATE h

FELLOWS AND h ^^ ASSOCIATES 1971 ESTIMATE PAID BY CERN

^ ACTUAL

CERN STAFF (EXPERIMENTAL PHYSICISTS)

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Fig. 1.2 The number of scientists at CERN on the 31 December of each year, for the years 1966 to 1975. (Source: CERN Annual Report, 1975, p.30^^).

CERN in 1965 - a concrete manifestation, if ever one was needed, of how European high- energy physics became concentrated in the Geneva laboratory. The data in Fig. 1.2 do not distinguish between the scientific activities in which the fellows and associates were involved. In fact far and away the bulk of them were attached to the so-called NP division where they were doing physics with electronic detectors: there were never more than 100, and generally around 50 to 70 non-CERN scientists on site in the Track Chamber division, while the Theory division usually had about 30 to 40 fellows and associates annually in its ranks. Figure 1.3, which charts the number of associates from the CERN member states and non-member states in the NP division makes the point clearly. Its overall shape mirrors that in Fig. 1.2. It shows that there was a more or less linear increase in the number of outside 'electronics' users from 1965 to 1970, when the number from the CERN member states reached almost 400, a sharp rise to a new plateau of about 650 scientists when the ISR was commissioned, and another sharp upturn once the preparations for the SPS experimental programme got under way. The other inter-

Notes: p. 36 CERNfrom the mid-1960s to the late 1970s

DMS •NonMS

1966 1966 1967 1970 1971 1972 1973 1974 197S

Fig. 1.3 The number of associates at CERN on the 31 December of each year in the NP division, i.e. mostly en• gaged in electronics experiments. A distinction is made between those from the member and those from the non- member states. As we do not have data drawing the same distinction for fellows, we have omitted this category of outside user. There were about 20 a year in NP in the first five years covered by the graph, and about 30 in the second. (Source: CERN Annual Reports, for the years in question.)

esting point about Fig. 1.3 is the jump in the number of associates from non-member states in 1971. It reflects the interest which US scientists, in particular, had in exploring the new energy range and the new mode of practice opened up by the ISR. There is one last point we would like to illustrate about the presence of outside users on the CERN site: their national distribution. This is shown for the 1970s in Fig. 1.4. Here we see that about 70% of the fellows and associates were from the 'Big Four' European countries, as one would expect. Within those the two that had no major national facility left in the 1970s, France and Italy, were the two best represented, while Germany and Britain were both considerably lower - although we notice the UK's figure beginning to climb at the end of the period as the high-energy machine at the Rutherford Laboratory was closed down and attention was focused on exploiting the SPS. The smaller countries are noticeable for the similarity in the size of their national scientific communities at CERN, which generally vary from 30 to 50, Switzerland being a little higher due, no doubt, to the proximity of its major universities and research centres to Geneva. The most important non-member state scientific community on the CERN site was, of course, that from the US, and it is interesting to note that its size in 1978 was comparable to that from Britain or Germany. The information we have given so far does not tell the whole story about the increasing role which CERN played as a service centre for the European physics community. In addition to the people on the site, one must also bear in mind the huge number of The growth in the user population 17

0 1971

Fig. 1.4 The evolution in the number of fellows and associates (paid by CERN or not) on 31 December of each year, broken down by nationaUty. (Source: CERN Annual Report, 1978, p. 157). physicists who remained at their home institutes to measure and analyze bubble chamber film^^. Only a few track chamber scientists - 50 to 70 for most of the decade from 1966 to 1975, as we said moment ago - are included in our global data in Figs. 1.2 and 1.4. The vast majority stayed in their universities or national research institutes. While we have very imprecise data on the numbers involved here, we can get some idea of the role which CERN had in this regard from data on the numbers of track chamber pictures taken in Geneva. This is shown in Fig. 1.5, which charts the number of pictures (in 1000s) taken at CERN (i.e. at the PS) and breaks that down into those which were distributed among groups which did not include a CERN component, and those that did. It should be said that the data usually only include pictures taken with hydrogen or deuterium either in the 1.5 m British chamber (for 1965 only), the 80 cm Saclay chamber (which was taken out of service in 1971 having taken 16 million pictures at CERN) and the CERN 2 m hydrogen chamber. We note that about 3-4 milUon pictures were taken between 1965 and 1968 (apart from a drop in 1966 caused by a major failure in the PS magnet supply), followed by a sharp rise to a new plateau of 6-7 million pictures. This was possible because the new PS magnet permitted double-pulsing of the CERN 2 m chamber. The drop in 1975 arose

Notes: p. 36 CERNfrom the mid-1960s to the late 1970s

Q Total • nonCERN only • CERN+nonCERN

1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975

Fig. 1.5 The number of bubble chamber pictures taken at CERN (in 1000s) mostly with the CERN 2 m and Sa- clay 80cm hydrogen bubble chambers (until 1971), but also including some pictures with Gargamelle, (1971-75), BEBC (1973-5) and HYBUC, a hyperon bubble chamber (1972-3). (Source: CERN Annual Reports for the years in question.)

because the CERN chamber underwent a major overhaul that year. Whereas it took 5.1 million pictures in 1974, it took about one-third as many during the three months it was in operation the year after. As we said a moment ago, we have no way of translating these data into a number of researchers. We do know that about 90% of the film taken at CERN was analyzed off- si te^^, while in 1972 CERN DG Jentschke indicated that the numbers of electronics and bubble chamber physicists were then about the same in Europe, a figure roughly confirmed by ECFA data^^. To a first approximation then, it seems that in the early 1970s there were about 1500-1750 European high-energy physicists wholly or partly dependent on CERN for their experimental data, their number equally spHt between the two then-standard experimental techniques, and about half of them regularly on the CERN site.

1.3 Machines and beams

The increasing demands of experimentation, and the need to satisfy an expanding user community whose physiognomy was traced in the previous section, posed ongoing tech• nical challenges to the engineers and applied physicists at CERN. The performance of the accelerators, the nature and the number of the beams, the power of the detectors all affected the kind and the quality of the physics that could be done: the direct correlation between the intensity of the PS and the fluctuations in the number of pictures taken with Machines and beams 19 the bubble chambers, as presented in Fig. 1.5, is just one indicator of the essential role they played in the experimental programme. In what follows we shall describe in some detail this dimension of the laboratory's life.

1.3.1 THE PROTON SYNCHROTRON

As we explained in the previous volume, when the PS was commissioned in November 1959 neither the physics community nor the laboratory were ready to launch an experi• mental programme around the machine^^. On the one hand there was a dearth of pro• posals for experiments in the new energy range opened up by the accelerator. On the other, there was a serious lack of beam transport equipment - bending and focussing magnets, separators and power suppUes. The first run with CERN's 30 cm hydrogen bubble chamber took place in March 1960 in an experimental hall cluttered with ancillary equipment. This situation was gradually rectified over the next two years. By the end of 1961 two batches of beam transport equipment had arrived and an order had been placed for 55 additional elements. Two short separators on loan from Padua University, which had been essential for the construction of relatively pure beams, were supplemented by the first of CERN's giant 10 m electrostatic tanks. The 2500 m^ of space in the North and South experimental halls had been liberated and four bubble chambers were on hand: the CERN 30cm hydrogen and Im heavy liquid chambers, an almost identical heavy liquid chamber on loan from the Ecole Polytechnique and an 80 cm hydrogen chamber built at Saclay. These were joined in 1964 first by the 1.5 m British hydrogen bubble chamber and then by CERN's 2 m hydrogen chamber, which had its first cool down in December and started doing useful physics soon thereafter. To accommodate all this equipment and a pro• gramme of electronics experiments using mostly spark chambers and Cerenkov counters an additional experimental area, the East Hall, had been commissioned in 1963. To get this equipment to function routinely and reliably required a major learning process. Contrary to what the engineers who built the machine originally thought - they expected to go home in 1959 once the PS reached its design energy - they soon 'realized that a machine of this kind will never be 'ready' - ready in the sense of a machine that is switched on and off* and runs without a change'. It had constantly to be modified and new systems had to be added 'to increase its capabilities as a source of high energy particles, to ease its operation, to improve control of the many parameters [affecting its performance], and to reduce damage due to irradiation of the synchrotron components' as the intensity of the circulating beam was increased^ ^ During the first six or seven years of PS operation the average intensity of the PS beam was increased by about a factor of ten to 10^^ protons/pulse. This was largely due to a better understanding of the beam dynamics in the Linac (50 MeV linear injector) and the installation, in 1966, of a new ion source which produced beams of up to 140mA at 50 MeV. The next major step forward was the installation, in 1968 of a new power supply for the main magnet. This enabled the machine either to be run regularly at higher beam

Notes: pp. 36 ff. 20 CERNfrom the mid-1960s to the late 1970s

energies (27GeV) or at higher intensities (by providing a long flat top for counter ex• periments and double pulsing for the hydrogen bubble chambers - cf. Fig. 1.5). By this means the PS reached a peak intensity of 2 x 10^^ protons/pulse in time for its tenth birthday in November 1969. In addition to developing the PS's capabiUties as a supplier of proton beams for ex• periments, it had to be adapted for use as an injector for the ISR. This required a further increase in the beam intensity of an order of magnitude. To achieve this higher intensity with a minimum beam blow-up due to space charge effects it was necessary to increase the injection energy further. Various ways of doing so were considered and finally it was decided that a four-ring booster synchrotron operating between 50 and 800 MeV would be the most suitable alternative. A special division (SI: Synchrotron Injector) was created to build it, and the new complex was used for physics for the first time in November 1973. The PS intensity was now about 5 x 10^^ p/p, and it was able to increase immediately the neutrino flux to the Gargamelle bubble chamber by a factor of three (at the time when pathbreaking studies on the weak neutral currents were being made - see below). A year later the PS reached an intensity of 10^^ protons/pulse for the first time, and was being prepared as an injector for the SPS. It only remains to add that as its intensity increased so too did its reliability. In 1967 the scheduled running time for physics experiments on the PS was around 6000 hours per year, and the unscheduled down-time on the machine due to unexpected faults was about 10% of that. From the mid-1970s onwards it retained the same scheduled running time (while also serving as an injector for the ISR) and the unscheduled down time had been reduced to about 400 hours a year^^. The second major research and development initiative undertaken to improve the power and versatility of the PS as an experimental tool was the production of extracted beams. These were virtually neglected when the machine was designed but rapidly assumed im• portance as the advantages of Using external rather than internal targets were appreciated by the PS engineers (reduction of proton losses in the machine) and the experimenters aUke (more freedom in the lay-out of the secondary beams around the target). Two different systems were developed. Fast ejection (the removal of the whole beam or part of the beam within two microseconds, the time it took to travel one turn in the accelerator) was required for bubble chamber work. It became a high priority in the early 1960s when DG Weisskopf decided to launch a major neutrino programme, and the first fast ejected beam came into operation in summer 1963. Slow ejection (peeling off a small portion of the beam every revolution for as long as 100 ms) was needed for electronics experiments. It was also first tried that year, but did not raise much interest among the physicists, who were happy with internal targets and could not easily assess the advantages of the new procedure. In the event the technique proved rather difficult to implement. It called on the operators systematically to increase the ampHtude of the oscillations of protons in the ring until the particles jumped into a septum magnet, which then ejected them. It was only towards the end of the decade that slow extraction systems which worked to the satis• faction of operators and customers alike was put in place^^. Machines and beams 21 Fig. 1.6 gives one some idea of the complexity of the beam layout around the PS and its variety at the end of 1974, its peak year of use before attention was switched to the SPS (see Fig. 1.7 below). We note that only two internal targets were in use, one providing five and the other two beams for the South Hall. A fast ejected beam from straight section 58 coupled with three possible target positions gave a choice of three beams for use with the CERN 2m hydrogen bubble chamber: U5 with three RF separation cavities, and two electrostatically separated beams labeled m6 and kg. The East area was also served by a slow ejected beam from straight section 62, this beam being divided into three branches each with its own external target, from which a variety of secondary beams were derived. Straight section 74 was used to provide a fast ejected primary beam for neutrino experi• ments in the South-East Hall with the heavy liquid chamber Gargamelle along with a spark chamber assembly. A beam could also be peeled off the target for the g-2 (magnetic moment of the muon) experiment. The West Hall (not shown in Fig. 1.6), was equipped with the Big European (hydrogen) Bubble Chamber (BEBC) and the Omega Spectrometer (an electronics facility we shall describe later). It was served by a beam extracted from straight section 16, which traveled in tunnels to the experimental area where it was divided into branches. One used fast ejection onto a target from which a secondary beam purified with three RF separation cavities was directed into BEBC. The other used slow ejection

GARGAMELLE o SPARK CHAMBERS

Fig. 1.6 Schematic diagram of PS external beams and experimental complexes in 1974. The West experimental area is not shown (Source: CERN Annual Report, 1974, 75).

Notes: p. 37 22 CERNfrom the mid-1960s to the late 1970s and an external target to produce a test beam and a secondary beam for the Omega. The main beam was also used to inject protons into the ISR rings in opposite directions. Embedded in this intricate web of equipment the PS, its intensity amplified by the booster in its first full year of operation, supported 27 counter experiments at the machine itself and produced tracks for 6.5 milUon bubble chamber photographs in 1974, as well as serving as an injector for the ISR.

1.3.2 THE SYNCHRO-CYCLOTRON

In contrast to the PS, the remaining two machines that we shall discuss, the SC and the ISR, had a rather more turgid life in our period. Originally conceived as an intermediate device to fill time until the PS was commissioned and to train European physicists on big accelerators, the synchro-cyclotron rapidly established itself as a research tool in its own right with an important particle physics and nuclear structure programme using muons and pions^"^. In parallel the SC supported ISOLDE, a nuclear structure facility which came onstream in 1967, and in which an isotope separator for studying radio-active elements was placed on-line with the extracted proton beam of the machine^^. During the mid-1960s the demand for the SC increased steadily, and the requirements of the users could only be met by increasing the number of available beams (from 5 to 9) and by extensive beam sharing and time sharing arrangements. By 1969 there were twenty user groups, totaling almost 150 physicists, 90% of them from outside laboratories, working at the machine. Over 6500 hours of time was available for physics for 'prime users' while 'parallel users' benefited from over 7200 hours, for an overall total of almost 14000 hours of machine time. Unscheduled downtime had been reduced to a mere 3% of operating time. That same year the SCIP (SC Improvement Programme), which had been under discussion for some time, got under way. Its aims were twofold. Firstly, to improve the extraction efficiency of the primary beam (which was only about 7%), so reaching at least 1/xA. Secondly, and more fundamentally, to increase the internal beam intensity by a factor of ten to about lO/iA by replacing the ion source and, above all, by increasing the repetition rate of the frequency modulator. To this end an order was placed with an external firm for a rotating condenser system to replace the tuning fork system which had been installed with the SC in 1957^^. The positive attitude expressed by the CERN management towards the SC, as evidenced by the decision to proceed with the SCIP, quickly began to wane. On the one hand, there was the danger of obsolescence as a physics tool for nuclear structure studies. A new generation of proton accelerators, called meson factories because their main aim was to deliver very intense secondary beams of muons and pions, was on the horizon not only across the Atlantic (at Los Alamos and in Vancouver) but in Switzerland itself (the SIN, or Swiss Institute for Nuclear Research, in VilHgen). This danger was ampHfied by un• precedented delays in the delivery of the rotary condenser. These factors, along with the constraints on the CERN budget imposed by the construction of the SPS, and the absence of a strong internal lobby of CERN physicists - the SC was largely used by non-CERN Machines and beams 23 scientists - meant that the possibiUty of shutting down the SC and transferring its nuclear physics programme to SIN was actively discussed in the early 1970s. By the end of 1972, and despite the doubts and hesitations, the future of the SCIP seemed assured by the convergence of a number of otherwise conflicting interests. As summarized by Hansen, the arguments for keeping the programme going were that

(i) It was in CERN's interest to hold on to its role as Europe's most prominent physics laboratory by having a broad scientific programme, and (ii) this also broa• dened the science-political support base in the member countries, of which especially the smaller ones (iii) were interested in institutionalized access to a big-science la• boratory with its intellectual climate and technical know-how. Finally (iv) some of those initially opposed to SCIP had come to fear that a transfer of activities to SIN would imply direct or indirect transfer of funds to SIN in an amount that would exceed the cost of continued SC operation^^.

In short CERN's wish to retain the support of all its users and their governments, in• cluding in the smaller member states, at a time when the laboratory was embarking on its most ambitious and expensive project ever, and was under attack for tending to see itself as 'a rather exclusive laboratory for privileged particle physicists' were crucial to the 'salvation' of the SC at this time^^. In June 1973 the SC machine was shut down to make the modifications foreseen in the SCIP; it was restarted for physics with a new name, SC2, in January 1975. But its troubles were not over. Certainly after some 18 months its extraction efficiency had been improved from about 7% to 70% and its internal beam intensity from l/zA to a mean value of about 2)uA and a peak value of about 4/iA. But the rotating condenser system was unreUable to the extent that between November 1975 and April 1976 the operating time for physics use was reduced to 1800 hours, with 1400 hours of unscheduled down time^^. And with money being tight the question arose again as to whether or not the SC programme should be maintained. Indeed around 1978 Directors General John Adams and Leon van Hove suggested that both the ISR and the SC should be closed to finance the LEP construction, and proposed again that the entire research programme could be shifted to SIN. Strong opposition from the ISOLDE users, in particular, once more prevailed. The SC was given a further lease of life on condition that it be used preferentially with the on-line separator. The machine was finallyclose d down in December 1990, and the ISOLDE programme was transferred to a new installation at the IGeV PS booster"^^.

1.3.3 THE INTERSECTING STORAGE RINGS

If the interest of the research programme and the pressure from the outside users and, indirectly, their national administrations, were able to protect the SC from the increasingly cost-conscious CERN management and Council delegates, the same cannot be said for the ISR. From the very beginning a major and ongoing effort was required to increase its luminosity to useful levels. Experimentation was further complicated by a number of

Notes: p. 37 24 CERNfrom the mid-1960s to the late 1970s unfortunate misconceptions about the kinds of detectors needed at its intersecting regions (see below) and by the sheer practical difficulties of using it as an experimental tool. The nadir was reached when first the J/psi (1974) and then the upsilon (1977) particles were discovered in the United States, even though the ISR could, in principle, have found them'^^ Although the construction of the ISR 'proceeded fairly uneventfully', to quote Kjell Johnsen who was the man responsible for it,"*^ it was in fact a tribute to careful planning and budgeting: officially the machine began operating four months ahead of schedule and it was built within the original cost estimate of 332 miUion Swiss francs in 1965 prices. Yet if it was a masterpiece of technology, its use as a physics tool was immediately compro• mised by one of the considerations which had always made the physicists wary of building it at all: its luminosity."^^ When the machine first worked this was about 10^^ cm"^ sec~\ to be compared with a design luminosity of 4 x 10^^ cm~^ sec~^ There were a number of reasons for this including transversal and longitudinal instabilities in the beams and the dispersive effects of beam-beam interactions. But the most important limitation to beam currents which quickly emerged was the beam-induced pressure rises. Protons in the cir• culating beams ionized part of the residual gas in the beam pipe. These ions were driven into the wall of the vacuum chamber by the beam potential of 1 kV and penetrated considerably deeper into the wall material than did the normal cleaning methods. This ion bombardment led to desorption from the wall, releasing more gas which could be ionized, with an avalanche effect which caused dramatic local vacuum variations followed by beam loss. The source of the difficulty being identified a major and long-drawn out programme was undertaken to remedy it. It involved the addition of about 500 titanium sublimation pumps, an increase in the vacuum bake-out time and temperature from 5 hours at 200 °C to 24 hours at 300 °C, and glow-discharge cleaning of all the critical vacuum components. The first two measures improved the vacuum in the rings from an average pressure of 3 X 10"^^ torr in 1973 to about 8 x 10"^^ torr in 1976. With the addition of glow discharge cleaning this could be improved by another factor of two or three by the end of the decade"*^. As the vacuum increased so did the luminosity. One needs to be careful here, however. For whereas CERN texts and graphs repeatedly referred to the maximum luminosity achieved at any one time, the regular performance of the ISR was generally far lower and depended strongly on beam energy"^^. Indeed we would go so far as to say that the ISR only reached its design luminosity of 4 x 10^^ cm~^ sec~^ during 'average' running in 1974, three years after it was officially commissioned (see Table 1.1). In addition to improving the vacuum, the other main way in which luminosity was increased at a specific intersection was by adding a system of quadrupoles which focused the beams to smaller vertical dimensions at the crossing point (the so-called low-beta insertion). A trial system of this kind was first installed at intersection 7 in 1974 using magnets borrowed from the Daresbury laboratory in the UK and from DESY in Ham• burg, along with spares from the ISR and PS Departments. The local luminosity was Machines and beams 25

Table 1.1 Operating conditions of the ISR as reported in the CERN Annual Report, 1974, p. 102.

Momentum, Running time. Beam current Luminosity, Luminosity, Gev/c per cent range, amps Maxima x 10^^ averages x 10^^

11.8 13.4 Ar-6 0.5 0.2 15.4 16.4 6-10 2 0.6 22.5 22.5 7-18 7 3 26.5 37.2 8-22 12.7 5 31.4 5.4 Ar-9 2.4 0.5 Different in 5.1 various various various each ring

increased by a factor of 2.3, this however being the Hmit obtainable with conventional quadrupoles. The next step was to develop superconducting quadrupoles, and when a system of this kind was eventually introduced in 1981 it increased the local luminosity in intersection 8 by a factor of 6.5"*^. The difficulties of experimental practice at the ISR added to its limitations as a routine physics tool. Complex scheduUng was required to harmonize the very different require• ments of the experiments. In one example cited later in this volume there were about 100 hours scheduled for physics in one week in May 1975, mostly at night, and most of the sessions called for different intersecting beam energies and/or beam currents'*^. The bulk of the experimental equipment was in the tunnel, and so could only be accessed for changes or repairs when the beam was switched off. The experiments themselves could influence the performance of the machine through the perturbing effects of their analyzing magnets and other equipment, and special operating conditions were required to prevent undue influ• ence on the circulating beam. There can be no doubt that many of these practical difficulties had been mastered by the early 1980s. A highly powerful axial-field magnetic detector was available, luminosity was at record levels in intersection 8, and a rich experimental programme was on the agenda. But against the background of past difficulties - in a community that prizes Nobels, missed opportunities are hard to forget -, with a steady migration of users in the mid- 1970s to the SPS (see Figs. 1.7 and 1.8) - which had orders of magnitude higher lumi• nosity and greater experimental flexibility even if its centre-of-mass energy was lower -, with high energy proton-antiproton coUisions available in the SPS, and with the financial constraints imposed by the construction of LEP, the ISR enthusiasts could not muster the support they needed to keep the machine alive. The first proton-proton collisions took place in the ISR on 27 January 1971. The last colliding beam run was terminated on 23 December 1983.

Notes: p. 37 26 CERNfrom the mid-1960s to the late 1970s

(PS + ISR + SPS) experiments

I 45

PS experiments

ISR experiments

1970 1971 1972 1973 1974 1975

Fig. 1.7 The number of experiments on the floor and in preparation during the years 1970 to 1975. The effects of the SC shutdown are apparent as is the attraction of the SPS as a research tool. The 300 GeV machine was- commissioned in June 1976 and its experimental programme began in earnest early in 1977 (Source: CERN Annual Report, 1975, p. 30)

1.4 Detectors

In commenting on Fig. 1.1 earlier in this chapter - which showed the overall evolution of CERN's expenditure and the functional distribution of resources within it - we noted the steady increase over the years in the cost of new experimental equipment, with a particularly sharp rise in the early 1970s. A considerable part of this money was spent on the acquisition and operation of new, state-of-the-art bubble chambers and electronic detectors which were demanded by an experimental practice which, if it was to remain internationally competitive, called for increasingly heavy, complex and costly equipment. The aim of this brief section is simply to explore a little further the circumstances which precipitated the change in shape of the curves for experimental equipment which we noted in Fig. 1.1. In the late 1950s much of the experimental apparatus used around an accelerator could be built by the physicists themselves with the help of a few technicians. With the emergence 27

Fig. 1.8 Number of physicists working on approved experiments at the ISR each year, as surveyed in August of that year. The lure of the SPS in the mid-1970s is confirmed. (Source: M. Jacob in CERN Yellow Report 84-13, 1984, p. 36). of bubble chambers at the end of that period, and of hydrogen bubble chambers in particular, expert groups of designers and constructors were required to build devices that were technically complex and potentially dangerous. Electronic detectors followed suit with a delay of about ten years. Initially custom built for a particular experiment, as accelerator energies increased they grew in size and complexity, and some of them became, Uke bubble chambers, general purpose faciUties serving a dedicated user community which carried out a wide range of experiments with them over a considerable period of time. In short by the end of the 1960s detectors had become 'technological achievements in their own right', to use John Adams' happy phrase"^^, and there was a visible, if sometimes blurred, dividing Une between those who designed, built and operated big detectors, and those who used them for research. As we explained earlier this spUt was formalized at CERN when Adams and van Hove took over as Directors General in 1976 and established the Experimental Physics Facilities and the Experimental Physics divisions. Two big bubble chambers, Gargamelle (heavy liquid) and BEBC (hydrogen) were commissioned at CERN in this period. The construction cost of the former was essentially paid by the French Commissariat a I'Energie Atomique, while the costs of building BEBC were shared equally between CERN, France and Germany (cf. Fig. 1.1)"^^. Table 1.2 Usts their overall cost and the size and structure of the teams required to build them, illus-

Notes: p. 37 28 CERNfrom the mid-1960s to the late 1970s

Table 1.2. The major hydrogen and heavy liquid chambers used at CERN in the late 1960s and the 1970s (Source: J. Adams in CERN Annual Report, 1977, 13-18).

Bubble Chamber-^ CERN 2m GargameUe BEBC

Construction approved/ 1959 1965 1967 commenced First pictures taken 1964 1970 1973 Magnetic field (Tesla) 1.7 2 3.5 (sc)^ Cost of construction 45MSF 30MSF (1969 prices) + lOOMSF (1966 prices) + (1964 prices)^ personnel and infra• 24MSF for liquids etc. structure Size of construction team 60 ~50, + 8 engineers and 90 (maximum)** physicists*^ Costs of operation ~ 8MSF/yr 7MSF/year -lOMSF/year Size of operating, maint• 39 + 7 44 60 enance and dpmt. team engineers ^BEBC used a superconducting magnet ^Of which 30MSF were material costs *^Rousset names about 80 people who were involved in the construction, development and operation of Garga• meUe. This does not include people employed by industry^^. **This figure is cited by Dominique Pestre in section 2.5, chapter 2, this volume.

trating the reasoning behind Adams and Van Hove's internal reorganization. Figs. 1.9 and 1.10 give one an idea of their physical dimensions. As for electronic detectors, two major devices should be mentioned. The split-field magnet spectrometer facility combined a huge magnet which sat astride an intersection at the ISR with an array of proportional wire chambers around it. Decided on in 1969, the SFM took five years and about 23 MSF to build and commission. The Omega spec• trometer combined a superconducting magnet with a variety of electronic detectors (spark chambers, proportional wire chambers, Cerenkov counters, etc) to study processes peaked in the forward direction. Initially intended for work at the PS, this device was decided on in 1968 and produced its first results in 1972. Its material cost alone amounted to some 20MSF. The SFM and the magnet of the Omega are illustrated in Figs. 1.11 and 1.12^^ As the energy of the machines increased at CERN in the 1970s, with the commissioning first of the SPS and then its conversion into a 270 GeV on 270 GeV proton - antiproton collider, so did of the size of the electronic detectors as well as of the experimental teams using them. By 1977 the average number of physicists in a team at the SPS was 28, of whom only three were CERN staff, and three teams had more than 50 scientists in them^^. One of these was the embryonic UAl collaboration, which was to build a huge, 2000-ton An electronic detector to search for the W and the Z at the coUider. This detector cost about 100 MSF to construct (though that figure is very approximate given the many collaborating institutions which put time and money into it) and in the early 1980s the team building and using it numbered over 100 scientists. CERN may have opened its The member states 29

Fig. 1.9 A general view of Gargamelle (Source: CERN Annual Report, 1977, 18) (Photo CERN-117-1-77). doors increasingly to outside users in the late 1960s and the 1970^^—t^ut it has to be said that the human and material resources now needed to run a high-energy physics pro• gramme left the laboratory no choice but to be welcoming^^.

1.5 The member states

For the first decade or so of its existence the member states' governments had barely 'interfered' in the hfe of CERN. They had watched with satisfaction its machines being commissioned in the late 1950s. They had paled at the additional resources required to exploit the PS in the early 1960s but, Great Britain apart, they had not protested. For most of them CERN was a high-energy physics laboratory par excellence, a shining example of successful European scientific and technological cooperation, a 'model' which inspired similar initiatives (e.g. in space). They were not going to allow narrow national self-interest to impede the laboratory's growth. Of course they were aware that, unfettered, the lab• oratory could spiral out of their control. But they placed their faith in their Council delegates, scientific statesmen and science administrators who stoutly defended their au• tonomy vis-a-vis their national state apparatuses, who knew CERN intimately (many of them had been involved from the very start of the project), and who insisted that they

Notes: p. 37 30 CERNfrom the mid-1960s to the late 1970s

Fig. 1.10 BEBC chamber body (Source: CERN Annual Report, 1977, 19) (Photo CERN-216-12-71).

could be counted on to put in place the necessary formal and informal mechanisms for controlling its expansion without damaging its health^"^. The relative autonomy of the Council to shape CERN's trajectory in consultation with the management, its role as a buffer between the laboratory and the national state bu• reaucracies, began to be chipped away, even seriously challenged in the late 1960s. This was not because there was a major turnover in the Council delegates, because a new generation with different values to the 'founding fathers' moved into positions of authority - far from it, as we saw in section 1.1. It was rather a consequence, as we mentioned earlier, of the new economic and political context in which CERN was situated: a slow• down in economic growth, fears over the 'technological gap', Gaullist-inspired tensions in the European (and Atlantic) alliance. Add to this a crisis in the 'parallel' European space effort, where governments became increasingly convinced that scientific and technological projects had to be situated in the broader framework of industrial poHcy, and we have the seeds for a re-assessment of what the aims of the Genevan laboratory should be^^. Fig. 1.11 The Split-Field Magnet at the ISR surrounded by Cerenkov counters (Source: CERN Annual Report, 1977, 77) (Photo CERN-173.7.77).

Fig. 1.12 A general view of the magnet of the Omega spectrometer (Source: CERN Annual Report 1977, 22) (Photo CERN-33-8-72).

Notes: pp. 37 ff. 32 CERNfrom the mid'1960s to the late 1970s

The Federal Republic of Germany's position over the construction of the 300 GeV Super Proton Synchrotron provides the most dramatic example of this new attitude^^. Two different issues were at stake here: the design of the machine itself and its location. In 1967 the scientists, administrators and industrialists on the German Atomic Energy Ad• visory Committee criticised the design then being discussed at CERN as technologically obsolescent and unnecessarily costly. They wondered in particular whether the use of new technologies Uke superconducting magnets and computer controlled beam handling had been seriously considered, and suggested that a more 'advanced' design could cut costs. Their point of reference was the proposal for the 400 GeV machine being promoted by Robert Wilson across the Atlantic for what was to become the Fermi National Accelerator Laboratory in Batavia, Illinois, a proposal which combined radical technological in• novation with sharp cost reductions. CERN managed to deflect these criticisms rather rapidly; the fact remains that, for the first time in the laboratory's history, one of its technical proposals had been criticised openly by influential personalities, including sci• entists and engineers, in a key member state. This served at once to undermine the claim, repeatedly made by the CERN staff", that they were the technological leaders in their field in Europe and, by showing that 'the experts' were divided, to undermine the authority of their Council delegates in the eyes of national state bureaucracies. The second issue over which Germany dug in its heels was that of the site for the SPS. The first tentative discussions on this question got under way in 1964. At the time it was assumed that the location would be somewhere other than Geneva. This was both to avoid concentrating all Europe's front-line high-energy physics capacity at CERN, and to allow member states other than France and Switzerland to capitalize on the prestige and the industrial benefits of having a site on their soil. The delicacy of the issue quickly emerged: nine of CERN's member states put in (sometimes multiple) bids for the laboratory. Fearful of losing control over the siting decision, the Council hoped to depoliticise the issue by basing the choice on 'objective criteria'. 'Three Wise Men' from among its number were selected and asked to assess the merits of the offers received. Their impartiality was 'assured' by choosing them from countries which had not offered sites, by their eminence - and by the shared understanding that the Council wanted above all to make a 'rational' choice which could not be contested by the national poUtical systems. The Site Evaluation Panel duly assessed the merits of the proposals along three axes pertaining respectively to the suitablity of the site in terms of construction, operation and conviviality, giving scores for each. No site got top marks in all three categories, though locations in France and in Italy came out best in two of them. The panel laid its report before the Council towards the end of 1967. The document was warmly praised - and promptly buried, its sought-for objectivity predictably impugned by the disagreements between the member states over the appropriateness of the evaluation criteria used. More to the point Germany demanded that the machine be located at its site in Drensteinfurt no matter what the position of this location was on the panel's league table (it received a j8 for suitability of construction, an a for operation, and a y for conviviality)^^. The German delegation was so recalcitrant on this point that even after The member states 33 they had agreed to join the project they forced the cancellation, at the last minute, of an interministerial meeting called by the Swiss to settle the site question in January 1970, fearing that the decision would not be in their favour. The problem was only resolved by a fundamental revision of the terms of the debate. In February 1970 Adams suggested that the accelerator be built in two distinct phases on the existing CERN site, so reducing sharply the costs of construction of the machine and spreading them over a longer time span. Germany could not but yield. Germany's attempt to impose its will on the Council and on its fellow member states in CERN was not only indicative of its determination to do all it could to build up its high- tech industry. More profoundly it was consonant with its growing self-confidence in the European political arena. For the first decade after the war Germany had to ease its way back gradually into political legitimacy. European collaborative ventures, particularly in sensitive areas like the nuclear and space, were an ideal avenue whereby the Federal Republic could at once shake off* the historical burden of her past, show herself to be dedicated to Europe and to the Western aUiance, and reinvigorate her national pro• grammes in key sectors of science and technology. Prudent at first, she gradually became more selfassertive. She demanded equal rights for the German language in official CERN documents. She participated in the construction of BEBC specifically so as to build up the technical knowledge of her scientists and engineers in this field, and even insisted that her share of the expenditure be channelled back into her industry, a demand for a 'fair return' which was totally at variance with CERN's usual contract policy^^. She insisted that the SPS, if built, contain the most advanced technologies available. And she was prepared to stop the entire project, to jeopardise the competitivity of the European high-energy physics eff'ort, if the new machine was not built on her soil. Of course it was normal for member states to demand that their interests be protected at CERN. But whereas previously they had left their delegates to the Council considerable scope to interpret what that entailed, now a different set of national interests, economic, industrial and poUtical, had come into play, interests which the Council delegates could not be reUed on to defend. The broader poUtico-economic fabric into which CERN had always been woven was changing its texture and the laboratory was obliged to change with it if it wanted to survive. It was not only Germany who saw in CERN a tool for furthering some of its broader national objectives. France did too, using the laboratory as an element in the new geo- poUtical orientations of de Gaulle's foreign policy in the late 1960s. In July 1967 CERN signed an official agreement with the appropriate Soviet authorities in which it undertook to design, build, test and instal a fast ejection system and radio-frequency particle se• parators for use at the 76 GeV proton synchrotron at Serpukhov, brought into operation a few months later. In return the CERN scientists could collaborate with their Soviet col• leagues in electronics and bubble chamber experiments at what was, for a while, the most powerful machine in the world. This initiative was surely inspired by the possibiUty of exploring the new research frontier opened up by the Soviet machine, but not by that alone. The CERN ejection system and separators were to feed a large hydrogen bubble chamber called Mirabelle, which had been built at Saclay and was to be installed on the

Notes: p. 38 34 CERNfrom the mid'1960s to the late 1970s floor in Serpukhov^^. And the decisions to collaborate with the Soviets were signed shortly after de Gaulle had withdrawn French forces from NATO command and in the midst of ongoing and increasingly more frequent interministerial meetings between the French and Soviet governments. The fast ejection system and the RF separators were technological objects at the service of European science and French foreign policy. CERN was not only an instrument of bilateral foreign policy. It was also a resource to be mobilised to express and to consolidate European scientific and political collaboration in other fields. In 1970 the European Southern Observatory signed an agreement with CERN whereby ESO's stafi* would construct a 3.6 m telescope to be installed in Chile using the administrative, technical and professional experience available on the laboratory site, including CERN offices and personnel.^^ Three years later, in May 1973, the Agreement setting up the new European Molecular Biology Laboratory (to be established in Heidelberg, Germany) was signed at CERN^^ Certainly such initiatives were not en• tirely novel in the 1960s: a key meeting establishing a preliminary organization to plan a European space effort had been held at Meyrin in 1960. What differed though was the nature of the agreements now signed, which were far more formal and politically sig• nificant than before. For the governments involved what was important was not just the physics done at CERN, but the fact that it was a source of technical innovation and accumulated know-how, an example of European scientific collaboration, the oldest member of a family of organizations held together by a core of senior science adminis• trators who circulated between them^^. As one engineer remarked who was present at the debate on collaboration with ESO in the CERN Committee of Council, 'It was remark• able that practically everyone [...] entirely lost sight of the original aim, the construction of the telescope, and rather emphasized the scientific importance of the collaboration be• tween astronomy and high-energy physics [and] common technical developments such as data handling, and the political aspect: the formation of a 'Communaute scientifique europeenne' in which there would be room also for other organizations for fundamental science'^"^. CERN was not to be an 'ivory tower' surrounded by the protective moat of a cooperative Council. It was increasingly part of European scientific, technological, in• dustrial and political integration. The laboratory had no choice but to respond. In 1974 it organized a conference at• tended by 300 industrialists, directors of appHed research, senior staff* from technical universities and science journalists where it displayed some of its technological achieve• ments in the hope that those present could find ways of applying the techniques and abiUties that had been developed at the laboratory^"^. In 1975 it published a report by an outside consultant on the economic returns from the member states' investments, in which it was claimed that 'for each Swiss franc spent by CERN in European industry, 5.5 Swiss francs of economic utility were generated'^^. That same year one number of the CERN Courier, the laboratory's inhouse magazine, was devoted almost entirely to describing the medical and other applications of accelerated nuclear particles^^. CERN's primary justi• fication still lay in its doing world-class high-energy physics research. It could not be its only one. Notes 35

When this history project got under way late in 1981 there was an air of anxiety at CERN. The member states, who had just agreed to fund a stripped-down version of LEP within tight budgetary constraints, were not only concerned about the 'practical' value of the laboratory, but also about the quality of the physics being done there. After three decades of activity CERN's performance, as measured by Nobel prizes, was uninspiring. The 1970s, in particular, were a period of frustration and disillusionment. One of the key findings of the early 1970s - weak neutral currents -, announced at CERN in 1973, was made by a team at Gargamelle but many of those involved felt that they were never given due credit for it. The difficulty of the experiment, the scepticism of senior physicists and management, the confirming and then conflicting results obtained with a parallel elec• tronics experiment at Fermilab - and the dread that CERN would publish a result dis- confirmed by a team in the US - , all served to create a corrosive climate of doubt and uncertainty which severely diluted the impact of the results obtained with the heavy-liquid chamber^^. This disappointment was amplified by the failure to observe the J/psi at the ISR in 1974, and the upsilon in 1977, due essentially to the low luminosity of the machine and the construction of detectors which were optimized in the forward direction when, it was realized later, there were particularly interesting events at wide solid-angles^^. It was against this background of missed opportunities that DGs Leon Van Hove and John Adams decided that CERN had to take the risk of launching a ppbar colUder project if it was to retain its credibility as a world-class high-energy physics laboratory. The first 'candidate events' for the long sought-for W boson were obtained in November 1982 using antiprotons cooled stochastically by a technique developed by Simon van der Meer, and a huge detector built by a collaboration led by Carlo Rubbia. A parallel experiment, led by Pierre Darriulat, confirmed the result.^^ The Nobel prize for physics followed in 1984 - and with it the 'proof that CERN and European physics could compete, at last, on an equal footing with the best in the world.

Notes

1. A. Hermann, J. Krige, U. Mersits and D. Pestre, History of CERN. Volume I. Launching the European Organization for Nuclear Research (Amsterdam: North Holland, 1987). 2. A. Hermann, J. Krige, U. Mersits and D. Pestre, History of CERN. Volume H. Building and Running the Laboratory (Amsterdam: North Holland, 1990). 3. An approach along these lines is taken in J. Krige, 'The politics of European scientific cooperation', in J. Krige and D. Pestre (eds) Science in the Twentieth Century (Harwood Academic PubUshers, 1997). See also D. Pestre, 'Vers un modele de relations scientifiques radicalement nouveau: le cas des physiciens allemands et fran9ais apres 1945', in Y. Cohen and K. Manfrass (eds), Frankreich und Deutschland. Forschung, Techno• logic und industrielle Entwicklung im 19. und 20. Jahrhundert (Miinchen: Beck, 1990), 130-41. 4. The formulation starts Maurice Jacob's survey of the ISR experimental programme in an invited talk he gave at the last meeting of the ISR experiments committee, just after the machine had been shut down; see M. Jacob and K. Johnsen, A Review of Accelerator and Particle Physics at the CERN Intersecting Storage Rings (CERN Yellow Report 84^13, 1984).

Notes: p. 38 36 CERNfrom the mid-1960s to the late 1970s

5. The quotations in this paragraph are from the article * 1959-1969. Ten Years in the Life of a Machine,' CERN Courier, 9(10), 1969, 337-347. It was compiled by the editor with the help of senior PS engineers. 6. This is from his introduction to the CERN Annual Report, 1977, 13. 7. For the way the technological gap in the space sector was then perceived on both sides of the Atlantic see, for example, Lorenza Sebesta, The Politics of Technological Cooperation in Space: US-European Negotiations on the Post-Apollo Programme', History and Technology, 11 (1994), 317-41. We should add that the need to *seir CERN to governments became even more pressing in the 1980s, see J. Krige, 'L'Image publique du CERN', AUiage N** 16-17 (Ete Automne 1993), 290-7. An EngHsh translation, 'The Public Image of CERN', appeared in J. Durant and J. Gregory (eds). Science and Culture in Europe (London: The Science Museum, 1993), 153-7. 8. This conception is clearly present in the German delegation's attitude on the SPS (see chapter 3) and in the arguments mobilized by the outside users in the early 1970s (see chapter 5). 9. I described these debates in more detail in volume I, chapter 8.4 (cf. note 1). 10. CERN Annual Report, 1978, 24. 11. Pestre describes the debate over the choice of the site for the SPS in chapter 3 (this voliune). 12. Pestre discussed the origins of the fissure along these lines in volume II, chapter 8 (cf. note 2). 13. This paragraph and the quotations therein owe much to Adams' extremely valuable introduction to the CERN Annual Report , 1977, pp. 13-24, wherein he reviews the major particle detectors at CERN. The quotations are on pp. 13 and 14 respectively. 14. Pestre describes the setting up of this structure in volume II, chapter 8 (cf. note 2). 15. For the debate surrounding the establishment of this committee see Russo, chapter 4, section 4.4 (this volume). 16. This procedure is briefly described by Hansen in chapter 9, section 9.2.2 (this volimie). Also chapter 5.5. 17. For some information on these substructures see Hansen, chapter 9, section 9.4.2 (this volume), and Pestre, chapter 2, section 2.3.2 (this volume). 18. For the importance of what we have called the CERN *lobby' see Pestre, volume II, chapter 7.1 (see note 2), and Dominique Pestre and John Krige, 'Some Thoughts on the Early History of CERN', in P. Galison and B. Hevly (eds) Big Science: The Growth of Large Scale Research (Stanford University Press, 1992), 78- 99. 19. This debate is discussed in my chapter 6, section 6.2 (this volume). 20. The data for the 1960s and 1970 is from the Annual Reports of the years in question. CERN Annual Report, 1976, 140, shows the change in the staff complement over the previous five years. 21. For more information on this see footnote 11 in my chapter 6 (this volume) on the ppbar collider. 22. This figure is given by Hermann in volume II, chapter 3.2.1, 49 (cf. note 2). 23. Document on ECFA notepaper entitled 'Farewell address to professor W. Jentschke pronounced at the CERN Council Session on December 17 1975 by the Chairman of ECFA'. Undated, unsigned (DGR21311). 24. This is described in detail in my chapter 5 in this volume. 25. The graph in the mentioned source is captioned 'the number of scientists reckoned in "man-years" drawing their research material from CERN during the years 1966-1975.' This suggests that it may also include those in their home institutes using bubble chamber film produced at CERN. A comparison of the data given in the graph with the tables regularly given in each Annual Report for the number of persons on the site at the end of the year reveals, however, that it is these figures that have been used. 26. 'Fermi National Accelerator Laboratory,' CERN Courier, 14 (9), 1974, 283-92. 27. For the role of CERN in building a European bubble chamber physics community in the early 1960s, see J. Krige, 'The Contribution of Bubble Chambers to European Scientific Collaboration,' Nuclear Physics B (Proc. Suppl.) 36 (1994), 419-26. 28. The figure, given by DG Gregory in 1970 (see CERN Annual Report, 1970, p. 13), is coherent with the trend established earlier in the decade (see Krige, ibid.. Table 1.3). Notes 37

29. For Jentschke, see CERN Annual Report, 1972, 23. The ECFA data is presented in Fig. 7 of my chapter 5 in this volume. 30. This is described in detail, and its causes analyzed, in my chapter 9 of volume II (cf. note 2). 31. See the account of the PS quoted in note 5 for the quotations in this paragraph. 32. These paragraphs are based primarily on the article cited in the previous note, on section 11.2.3.2 of chapter 11 by Crowley-Milling, in this volume, and on John Adams' paper on The CERN Accelerators,' CERN Annual Report, 1976, 12-3. 33. Crowley-Milling (sections 11.5.5.1, 11.5.5.2) of chapter 11 in this volume gives technical information on fast and slow extraction. See also the article in the CERN Courier cited in note 5. 34. This programme is described by Ulrike Mersits in volume II, chapter 3 (cf. note 2), and by Gregers Hansen in chapter 9, section 9.3, this volume. 35. ISOLDE is the subject of a separate chapter by Gregers Hansen in this volume. 36. The operating parameters of the SC cited here are taken from the CERN Annual Report, 1969,14-5,43. For details on the SCIP see Hansen, chapter 9, section 9.5, this volume. 37. From Hansen, chapter 9, section 9.5.4, this volume. 38. ibid., for the quotation, which resonates with the remarks made by the ECFA Chairman (cf. note 23 ) and the general dissatisfaction of the user community described in my chapter 5. 39. This data is from Adams' introduction to the CERN Annual Report, 1976, p. 11-12, where his lack of enthusiasm for maintaining the SC is manifest. 40. The renewed debate over the future of the SC between 1979 and 1981 is described by Hansen, chapter 9, section 9.7, this volume. 41. The construction and operation of the ISR is the subject of a detailed study by Arturo Russo in chapter 4 in this volume. See also the report by Jacob and Johnsen cited in note 4. 42. See the Yellow Report cited in note 4, at p. 4. 43. Dominique Pestre in chapter 12 of volume II of the CERN history (see note 2) has described the strong opposition by physicists to the ISR in the years leading up to the decision to build it, which was taken in 1965. 44. Russo, Fig. 4.7, chapter 4, this volume, depicts the improvement in the vacuum over time. 45. See for example the usual graph provided by Johnsen (Fig. 9 in the Yellow Report cited in note 4) which is reproduced as Fig. 4.7 in chapter 4 by Russo, this volume. This graph gives the maximum luminosity and states that the design luminosity was reached at the end of 1972. The (maximum) luminosity given for 1974 is about 2 X 10^^ cm~^ sec~\ which is to be compared with the figures from the Annual Report for that year reproduced in Table 1. 46. For this paragraph see the CERN Annual Reports, 1974, 100 and 1975, 113, as well as Johnsen's account in the CERN Yellow Report 84-13, 1984, section 3.1.9 (cf note 4). 47. See Fig. 4.3 in Russo, chapter 4, this volume. 48. See his introduction to CERN Annual Report, 1977, 13. 49. The decisions to build the two big bubble chambers are descibed in detail by Dominique Pestre in the next chapter of this book. An account of the construction and operation of the former has also been provided by Andre Rousset, one of the physicists intimately involved with the project from the start - see A. Rousset, Gargamelle et les courants neutres (Paris: Ecole des Mines, 1996). 50. Op. cit. note 49, Annex 1-2. 51. Arturo Russo, in chapter 4 (this volume) devotes considerable attention to the decision to equip the ISR with a Split-Field Magnet detector, and Ivana Gambaro has dedicated an entire chapter (chapter 12) to electronic position detectors in general, including the SFM. 52. This data is provided by Van Hove in the CERN Annual Report, 1977, 25. 53. This detector, and the structure and functioning of the collaboration which built it, are explored in detail in my chapter 7, this volume. 54. On the role of the CERN Council, see note 18. 38 CERNfrom the mid-1960s to the late 1970s

55. This is descibed at length in J. Krige and A. Russo, Europe in Space, 1960-1973, Report-ESA SP1172 (Noordwijk: ESTEC, 1994). 56. These paragraphs are based on Dominique Pestre's chapter 3, this volume. 57. See the Report of the Site Evaluation Panel on the Site Offers by the Member States for the 300 GeV Accelerator Laboratory, CERN/761, 4/12/67, 12. 58. See Pestre chapter 2, section 2.4 (this volume). 59. For one of many descriptions of the CERN/Serpukhov collaboration which, of course, makes no reference to the political dimension of the arrangement, see the report in the CERN Courier, 10 (2), 1970. 60. This is described extensively in A. Blaauw, ESO's Early History. The European Southern Observatory from Concept to Reality (Garching bei Miinchen: ESO, 1991), chapter 9. 61. There is a report in CERN Courier, 13(5), 1973, 139. 62. Just two examples: Bannier was the ESO Council President at the time the ESO-CERN agreement was signed, having taken over from Funke in 1969. At that time too Zelle was the chairman of the ESO Finance Committee, and also Vice-President of the European Molecular Biology Conference. 63. Letter Zilverschoon to Blaauw, 27/11/69, quoted in Blaauw, op. cit., 171. 64. There is a report on the meeting, whose proceedings were also published as a Yellow Report, in the CERN Courier, 14(4), 1974, 111. 65. 'Paying our Way? An Analysis of the 'Economic Utility' of CERN', CERN Courier, 15(9), 262-4. The findings were published as a Yellow Report, author H. Schmied. It was followed by another study some years later. 66. This was Volume 15, N° 11. 67. See Winter's chapter 10.2 (this volume) for an account of the weak neutral currents story. Historians of science have also worked extensively on it, e.g. P. Galison, 'How the First Neutral-Current Experiment Ended,' Rev. Mod. Phys. 55 (1983), 477-508, and How Experiments End (Umwersity of Chicago Press, 1987), and A. Pickering, 'Against Putting the Phenomena First: The Discovery of the Weak Neutral Current', Stud. Hist. Phil, of Science 15 (1984), 85-117. A participant in the experiment has also just published another account, cf. Rousset, note 49, where a more extended reference list can be found. 68. These points are made in Jacob (cf. note 4) and in Russo, chapter 4.4 and Gambaro, chapter 12.4.4.2, this volume. 69. The basis for this programme is described extensively in my chapters 6 and 7, this volume. See also Winter, chapter 10.3 and Crowley-MilHng, chapter 11.3.