After three years of work, the ATLAS detector cavern (35 x 55 x 40 metres) is fully excavated and completed. CERN officials and dignitaries celebrate the first new LHC cavern on 4 June 2003, complete with an alpinhorn player.
After five years of innovative and ingenious civil engineering, the ATLAS detector cavern (35 x 55 x 40 metres) was fully excavated. ATLAS, CERN officials, and political authorities, including the President of the Swiss Confederation Pascal Couchepin, celebrated the inauguration of the first cavern on the Large Hadron Collider on 4 June 2003. Installation of the detector in the cavern began soon after.
Two CERN experiments, ATHENA and ATRAP, created thousands of atoms of antimatter in a “cold” state in 2002. Cold means that the atoms are slow moving, which makes it possible to study them before they meet ordinary matter and annihilate. Antihydrogen formed in the experiments when cold positrons and antiprotons were brought together and held in a specially designed “trap”. Once formed, the electrically neutral antihydrogen atoms drifted out of the trap and annihilated.
Construction workers use a modified cement truck on stilts to reinforce the floor of the ATLAS cavern.
A digger removes the final sods of earth from the sides of the cavern that will house the ATLAS detector.
A new accelerator, REX-ISOLDE, is put into operation on 31 October 2001. This post-accelerator has opened up new fields of research using radioactive ion beams of higher energies. REX-ISOLDE can provide post-accelerated nuclei covering the whole mass range from He to U for reaction studies and Coulomb excitation with energies up to 3 MeV/u. To this day, REX has accelerated over 100 isotopes of more than 30 different elements.
The Large Electron–Positron collider was shut down for the last time at 8.00 a.m. on 2 November 2000. Members of government from around the world gathered at CERN on 9 October to celebrate the achievements of LEP and its 11 years of operational life. With the tunnel now available for work, teams began excavating the caverns to house the four big detectors on the Large Hadron Collider.
The LEP established the Standard Model of particle physics with unprecedented precision, including all its radiative corrections. These led to predictions for the masses of the top quark and Higgs boson, which were confirmed later on. After these precision measurements, the Nobel Prize in Physics 1999 was awarded to Gerardus 't Hooft and Martinus Veltman "for elucidating the quantum structure of electroweak interactions in physics".
Bulgaria became a full member state of CERN on 11 June, when it gave UNESCO its instrument of ratification of the constitutive Convention of CERN.
At a ceremony during the council meeting, the Bulgarian flag was hoisted outside CERN for the first time to join the flags of the organization's 19 other member states. Bulgaria's deputy Prime Minister Vesselin Metodiev said that one of the priorities of the Bulgarian government is to develop and maintain competitive science in Bulgaria. "Our membership in CERN is an important step in this direction as it will enable many Bulgarian scientists, engineers and technical staff to work at the leading edge of science and contemporary technologies," he said.
CERN Director-General Luciano Maiani said: "Bulgaria's membership of CERN is another step forward in the unique European collaboration in fundamental physics research. We are delighted to welcome our Bulgarian colleagues to our community."
LHCb is the fourth experiment approved for the LHC. The experiment will study the phenomenon known as CP violation, which would help to explain why matter dominates antimatter in the universe.
As construction workers are preparing the work site for the CMS-detector cavern, they unearth 4th century Gallo-Roman ruins. The find delays work for 6 months while archaeologists excavate the site.
The archaeologists find a Gallo-Roman villa with surrounding fields, as well as coins from Ostia (a seaport of Rome), Lyons in France (then Gaul) and London.
Team of engineers begin excavating a series of underground caverns in Meyrin, Switzerland. These caverns will be home to the ATLAS Experiment and its supporting infrastructure.
The Monopole and Exotics Detector at the LHC proposes to build a detector to search for highly ionizing particles and slow exotic decays at the LHC. The letter of intent marks the first official use of the name MoEDAL. It will be the LHC’s seventh detector.
At the December session of the CERN council, representatives of the United States sign an agreement to contribute $531 million to the Large Hadron Collider (LHC) project. Martha Krebs, Director of the Office of Energy Research (DOE) and Bob Eisenstein, Assistant Director of Physical and Mathematical Science at the National Science Foundation sign on behalf of the US, and CERN Director-General Christopher Llewellyn Smith signs on behalf of the laboratory.
At the same meeting, the US is granted observer status at CERN.
The Total Cross Section, Elastic Scattering Diffraction Dissociation collaboration proposes to build a detector to measure the basic properties of proton-proton collisions at high energy. The letter of intent marks the first official use of the name TOTEM.
The LHC Experiments Committee and CERN Director-General, Chris Llewellyn Smith, approve the construction of the ATLAS detector. As the first Technical Design Reports are approved, ATLAS teams all over the world begin building detector components and worked on final technical developments.
Satellite image showing spring ice melt underway on Lake Baikal (Image: NASA Earth Observatory)
NT200, a detector in lake Baikal played a pioneering role in neutrino astronomy. NT200 was constructed between 1993 and 1998. However, in 1994 NT200 detected two neutrino events when only 36 of the final 192 photodetectors were set up. These were the first of several hundred thousand atmospheric neutrinos which NT200 later detected.
Many expansions have taken place recently and neutrino research at lake Baikal continues to be an important part of the efforts to better understand the high energy process that occurs in the far-distant astrophysical sources, to determine the origin of cosmic particles of the highest energies ever registered, to search for dark matter, to study properties of elementary particles and to learn a great deal of the new information about the structure and evolution of the universe as a whole.
The CERN research board officially approves the ALICE experiment. Re-using the L3 magnet experiment from the LEP, ALICE is designed to study quark-gluon plasma, a state of matter that would have existed in the first moments of the universe.
In 1996 CERN's antiproton machines – the Antiproton Accumulator (AC), the Antiproton Collector and the Low Energy Antiproton Ring (LEAR) – were closed down to free resources for the Large Hadron Collider. But a community of antimatter scientists wanted to continue their LEAR experiments with slow antiprotons. Council asked the Proton Synchrotron division to investigate a low-cost way to provide the necessary low-energy beams.
The resulting design report for the Antiproton Decelerator concluded:
The use of the Antiproton Collector as an antiproton decelerator holds the promise of delivering dense beams of 107 protons per minutes and low energy (100 MeV/c) with bunch lengths down to 200 nanoseconds.
The Antiproton Declerator project was approved on 7 February 1997.
Four years after the first technical proposals, the experiments CMS and ATLAS are officially approved. Both are general-purpose experiments designed to explore the fundamental nature of matter and the basic forces that shape our universe, including the Higgs boson.
LEP's year was dominated by preparations for its energy upgrade from LEP1 to LEP2. A new way of operating the machine was mastered, and new accelerating cavities were installed. In December 1995, LEP took its first step toward LEP2, with an increase of energy from 90 to 140 GeV, and earning the label LEP 1.5. The reconfigured machine worked straight away, and the experiments produced new results soon after. ALEPH, one of the LEP experiments, found some unexpected results which appeared difficult to understand on the basis of known physics. Read more.
The Large Hadron Collider (LHC) project is approved by the CERN council in December 1994. The LHC study group publish the LHC Conceptual Design Report, which details the architecture and operation of the LHC, in October 1995.
A team led by Walter Oelert created atoms of antihydrogen for the first time at CERN’s Low Energy Antiproton Ring (LEAR) facility. Nine of these atoms were produced in collisions between antiprotons and xenon atoms over a period of 3 weeks. Each one remained in existence for about 40 billionths of a second, travelled at nearly the speed of light over a path of 10 metres and then annihilated with ordinary matter. The annihilation produced the signal that showed that the anti-atoms had been created.
This was the first time that antimatter particles had been brought together to make complete atoms, and the first step in a programme to make detailed measurements of antihydrogen.
The hydrogen atom is the simplest atom of all, made of a single proton orbited by an electron. Some three quarters of all the ordinary matter in the universe is hydrogen, and the hydrogen atom is one of the best understood systems in physics. Comparison with antihydrogen offers a route to understanding the matter–antimatter asymmetry in the universe.
The CERN Council admits Japan as an observer state. Japan announces a financial contribution to the LHC. The Japanese Minister for Education, Sciences and Culture offers a Daruma doll to CERN’s Director-General. According to Japanese tradition, an eye is painted on the doll to mark the beginning of the LHC project and the second eye must be drawn at the time of its completion. Japan makes two other major financial contributions to the LHC project in 1996 and 1998.
Industrial robots are installed for manipulation of ISOLDE targets, which allows all target changes and manipulations of used target-ion-source systems to be made without human intervention.
The CERN council approves the construction of the Large Hadron Collider. To achieve the project without enlarging CERN’s budget, they decide to build the accelerator in two stages.
The ATLAS Collaboration submits the technical proposal of the experiment to the LHC Experiments Committee. Approval to proceed with technical design reports would be granted in early 1996, followed by the submission of the first report on 15 December of the same year. A long series of Technical Design Reports follow.
By the end of 1994, the Web had 10,000 servers - of which 2000 were commercial - and 10 million users. Traffic was equivalent to shipping the collected works of Shakespeare every second.
In October 1994, Tim Berners-Lee founded the World Wide Web Consortium (W3C) – at the Massachusetts Institute of Technology laboratory for computer science – in collaboration with CERN and with support from DARPA and the European Commission. Sir Berners-Lee moved to the Massachusetts Institute of Technology (MIT), from where he remains Director of the World Wide Web Consortium (W3C).
In May 1994, Robert Cailliau organized the world’s First International World Wide Web Conference at CERN. It was attended by 380 users and developers, and was hailed as the “Woodstock of the Web”.
The first prototype bending-magnet for the LHC reaches a field of 8.73 Tesla, which is higher than the 8.4 Tesla field at which the LHC will operate in 2012.
Superconducting magnets must be "trained" so that they can maintain the superconducting state necessary to achieve such high fields. Any abnormal termination of the superconducting state, which switches the magnet back to its normal, resistive state, is called a "quench."
LHC Director Lyn Evans receives a hand-written note as he sits in a Finance Committee meeting. It reads:
Message de J.P Goubier et R.Perin à L Evans
on a attaint 8,73 tesla
They mean "sans quench" - a pun on the French word "cent" or "one hundred", which is pronounced the same as the word for "without".
On 3 December 1993, the Akeno Giant Air Shower Array (AGASA) recorded a cosmic ray with an energy of 2x1020 eV. This was a particularly well-measured event because the cosmic rays fell completely inside the detector array and arrived from a nearly vertical direction. This was the highest energy cosmic ray observed at AGASA and greatly exceeded that of any known source.
AGASA consists of 111 particle detectors dispersed about a kilometer apart over a 100 square kilometer area. Each detector is roughly 2.2 square kilometers in size. AGASA was completed in 1991 and has been measuring cosmic rays ever since.
Due to concerns linked to rising costs, the US government votes to cancel the Superconducting Super Collider project. The LHC becomes the sole candidate for a new high-energy hadron collider.
The Czech Republic joins
Statement of the government of the Czech Republic on questions of membership in International Governmental Organizations:
In connection with the dissolution of the Czech and Slovak Federal Republic on December 31, 1992, the Government of the Czech Republic declares the interest of the Czech Republic to be, after January 1, 1993, a fully-fledged member of the following international governmental organizations in the activities of which it has so far participated within the membership of the Czech and Slovak Federal Republic: [CERN is listed along with 51 other international organizations.]
The Czech Republic joined CERN as a member state on 1 July 1993.
The Slovak Republic joins
From CERN council minutes, 17 March 1993:
At its 297th meeting on 17 March 1993 Committee of Council discussed the accession of the Slovak Republic. Delegations indicated their unanimous support for the proposal of the accession.
The Slovak Republic joined CERN as a member state on 1 July 1993.
On 30 April 1993, CERN issued a statement putting the Web into the public domain, ensuring that it would act as an open standard. The move had an immediate effect on the spread of the web. Further licensing actions were taken to allow the Web to evolve and flourish. By late 1993 there were over 500 known web servers, and the WWW accounted for 1% of Internet traffic.
The collaboration for A Large Ion Collider Experiment (ALICE) propose to build a detector at the LHC to study heavy-ion collisions. The letter of intent marks the first official use of the name ALICE.
From January 1993, the National Center for Supercomputing Applications (NCSA) at the University of Illinois, provided pre-releases of its Mosaic browser for the Unix X Window System. The first official release was on 21 April 1993. Mosaic quickly gained popularity, becoming the browser of choice, with its user-friendly graphical interface and easy installation. Versions of Mosaic running on PC and Mac became available later that year.
By a letter dated 16 December 1992, the Permanent Mission of the Czech and Slovak Federal Republic (CSFR) to the United Nations in Geneva informed CERN that the Czech and Slovak Federal Republic would cease to exist on 31 December 1992 and that two new states – the Czech Republic and the Slovak Republic – would succeed it as from 1 January 1993.
The letter states:
It is the understanding, readiness and agreement of the both (sic) Czech and Slovak Republics that they will smoothly assume the total obligations of the CSFR with CERN after December 31, 1992 – develop the (sic) cooperation with CERN practically under the same conditions as the CSFR – and become full-fledged members of CERN.
The Toroidal LHC Apparatus collaboration propose to build a multipurpose detector at the LHC. The letter of intent they submit to the LHC Experiments Committee marks the first official use of the name ATLAS. Two collaborations called ASCOT and EAGLE combine to form ATLAS.
The Compact Muon Solenoid (CMS) collaboration proposes to build a multipurpose detector at the LHC. The letter of intent they submit to the LHC Experiments Committee marks the first official use of the name CMS.
The ATLAS Collaboration proposes the construction of a general-purpose detector at the Large Hadron Collider. The Letter of Intent was submitted to the LHC Experiments Committee, which marked the first official use of the name ATLAS. The Letter identified a number of conceptual and technical design options, including a superconducting toroid magnet system.
By late 1992, the WWW project had a growing list of early web servers. They were mainly located at academic sites collaborating with CERN but interest was starting to spread beyond academia. Development was also progressing on early graphical browsers (e.g. MIDAS by Tony Johnson from SLAC, Viola by Pei Wei from technical publisher O'Reilly Books, and Erwise by Finnish students from Helsinki University of Technology).
Hungary joined CERN in 1992, but Hungarian groups have participated in numerous experiments at CERN almost since its foundation. From the beginning, these collaborations were coordinated by the KFKI Research Institute for Particle and Nuclear Physics (RMKI) of the Hungarian Academy of Sciences, with the participation of physicists and engineers of the Institute of Nuclear Research (ATOMKI) of the Hungarian Academy of Sciences, of the Institute of Experimental Physics of the University of Debrecen, and of the Departments of Atomic and Theoretical Physics of Loránd Eötvös University in Budapest. High-energy physics thus has two centres in Hungary: Budapest and Debrecen, and their researchers form joint groups in all related activities. Hungarian research groups have contributed to many experiments at the Super Proton Synchrotron and the Large Electron-Positron collider.
Today, Hungarian participation in CERN concentrates on high-energy proton-proton and heavy-ion collisions in the framework of the CMS, ALICE and TOTEM collaborations at the LHC. Hungarian physicists are also involved in testing matter-antimatter symmetry in the ASACUSA experiment at the CERN Antiproton Decelerator. An important asset for the experimental activities is the Budapest site of the LHC Computing Grid system located at RMKI, which is to serve as the Tier-2 centre for Hungarian high-energy physics and also for other, interdisciplinary applications.
The Czech and Slovak Federal Republic
From council minutes on 20 December 1991:
In June 1991 the Director-General informed the Scientific Policy Committee and the Committee of Council of the wish of the Czech and Slovak Federal Republic to accede to CERN. Subsequently, in a letter dated 29 August 1991, the Czechoslovak Deputy Prime Minister and Minister of Foreign Affairs formally requested that the Czech and Slovak Federal Republic become a Member State of the Organization.
This letter was communicated to the Delegations by the President of Council on 10 September 1991. Official negotiations were conducted on 25 October 1991 and resulted in an "Aide-Mémoire", dated 25 October 1991, between CERN and the Czech and Slovak Federal Republic. At its 203rd meeting on 18 and 19 December 1991 the Committee of Council considered the document and decided to recommend to Council the terms and conditions for the accession of the Czech and Slovak Federal Republic.
The Czech and Slovak Federal Republic joined CERN as a member state on 1 July 1992.
First experiment at the ISOLDE Proton-Synchrotron Booster.
The first experiment was carried out on June 26, where the beta-proton decay of the neon isotope with mass number 17 was studied. This experiment was relevant for the understanding of nuclear halo structure, first proposed at ISOLDE.
The new ISOLDE PSB Facility has two isotope separators, a general-purpose separator with one magnet (GPS) and a high-resolution separator with two magnets, similar to the ISOLDE III design. The target handling in the facility is fully automatized with robots.
By January 1992, the WWW software at CERN had matured from an early prototype to a useful and reliable service. Through CERN’s Computer Newsletter, thousands of scientists learnt how they could use the web to access a useful set of information, e.g. phone numbers, email addresses, news groups, as well as computing and software documentation.
On 12 December 1991, the first web server outside Europe was installed at the Stanford Linear Accelerator Center (SLAC) in California. It provided access to SPIRES, a database with information for scientists working in HEP (High Energy Physics), including the ability to search for publications.
The Fly's Eye Mirrors (Image: Courtesy of University of Utah)
On 15 October 1991 the HiRes Fly's Eye cosmic-ray detector in Utah, US, recorded the highest-energy cosmic ray ever detected. Located in the desert in Dugway Proving Grounds 120 kilometres southwest of Salt Lake City, the Fly's Eye detects cosmic rays by observing the light that they cause when they strike the atmosphere.
Cosmic rays are mainly (89%) protons – nuclei of hydrogen, the lightest and most common element in the universe – but they also include nuclei of helium (10%) and heavier nuclei (1%), all the way up to uranium. When they arrive at Earth, they collide with the nuclei of atoms in the upper atmosphere, creating more particles, which start a cascade of charged particles that can produce light as they fly through the atmosphere.
The charged particles of a cosmic ray air shower travel together at very nearly the speed of light, so the Utah detectors see a fluorescent spot move rapidly along a line through the atmosphere. By measuring how much light comes from each stage of the air shower, one can infer not only the energy of the cosmic ray but also whether it was more likely a simple proton or a heavier nucleus. The Utah researchers measured the energy of the unusual cosmic ray event in 1991 to be 3.2x1020 eV.
On 15 October 1991 the Fly's Eye cosmic-ray detector in Utah, US, recorded the highest-energy cosmic ray ever detected. Located in the desert in Dugway Proving Grounds 120 kilometres southwest of Salt Lake City, the Fly's Eye detects cosmic rays by observing the light that they cause when they strike the atmosphere.
Cosmic rays are mainly (89%) protons – nuclei of hydrogen, the lightest and most common element in the universe – but they also include nuclei of helium (10%) and heavier nuclei (1%), all the way up to uranium. When they arrive at Earth, they collide with the nuclei of atoms in the upper atmosphere, creating more particles, which start a cascade of charged particles that can produce light as they fly through the atmosphere.
The charged particles of a cosmic ray air shower travel together at very nearly the speed of light, so the Utah detectors see a fluorescent spot move rapidly along a line through the atmosphere. By measuring how much light comes from each stage of the air shower, one can infer not only the energy of the cosmic ray but also whether it was more likely a simple proton or a heavier nucleus. The Utah researchers measured the energy of the unusual cosmic ray event in 1991 to be 3.2 × 1020 electronvolts (eV).
In August 1991, Sir Berners-Lee announced his WWW software on Internet newsgroups and interest in the project spread beyond the physics community. The first announcement was on 6 August 1991 to alt.hypertext, a newsgroup for hypertext enthusiasts. He described the project and provided instructions for obtaining the WWW software from CERN.
The first contacts between Poland and CERN were established in 1959 when several scholarships were awarded to young Polish physicists from Cracow and Warsaw. This soon developed into a wider collaboration between CERN and Polish institutes. In 1964 Poland became an observer state at CERN, the only country from Eastern Europe to accede to this status. In 1991, Poland became the 16th member of CERN, and thus the first member state from the former Eastern block.
Today, high-energy physics in Poland is concentrated in six higher educational establishments and two research institutes. The biggest groups are active in Cracow and Warsaw. Polish groups have a widely recognized technical experience and good computing resources, and are well integrated in the international particle and astroparticle physics community. Strong groups participate in all LHC experiments building important parts of the equipment, such as radiation resistant silicon detectors and electronics for the inner tracking detector in the ATLAS experiment, electronics for the muon trigger in the CMS detector, straw trackers for the LHCb Outer Detector, and contributions to the lead-tungstate crystals for the photon spectrometer (PHOS) on the ALICE detector.
More than 100 Polish engineers and technicians from Cracow and Wroclaw participated in the commissioning of the LHC. Polish industry was also involved in the construction of the LHC and its experiments.
By March 1991, a simple ‘Line-Mode’ browser was made available to users of CERN’s central computers. Although it had less features than the more sophisticated NeXT browser/editor, it had the big advantage of being able to run on a wider range of computers. It was written by Nicola Pellow during her student work placement at CERN. A project to restore the first ever Website includes a description of the Line Mode browser.
On 1 January 1991, Finland joined CERN as the organization's 15th member state. The Finnish government ratified the CERN convention and deposited the formal accession papers with the Director-General of UNESCO on 28 December 1990. On 28 January 1991 a full delegation of Finnish politicians and scientists came to Geneva to celebrate the official hoisting of the Finnish flag in front of the CERN entrance. The Finnish delegation was led by Jaakko Numminen, Secretary-General of the Finnish Ministry of Education and Science, and Antti Hynninen, Finnish Ambassador to the United Nations.
Finland has a long-standing tradition of research in theoretical high-energy physics. Since the beginning of the 1980s, experimental research has focused on key experiments at the high-energy frontier. These activities range from the UA1 experiment at the CERN proton-antiproton collider, the DELPHI experiment at LEP and the CDF experiment at the Fermilab Tevatron to significant contributions to three LHC experiments: ALICE, CMS and TOTEM. In parallel, Finnish research groups participate in experiments at the ISOLDE facility. It was therefore logical that Finland joined CERN as a member state in 1991.
Present and future experimental activities are based on four cornerstones: the Helsinki Institute of Physics, which coordinates experimental HEP activities in Finland; a good laboratory infrastructure for semiconductor and gas detector construction and development; a strong local link between phenomenology and experiment, especially in the fields of new physics and quantum chromodynamics; and a good university education system. With the exception of CDF, all experimental and a large part of the phenomenological research are linked to CERN activities.
The highest priority of the Finnish high-energy-physics community is a successful completion of the approved Large Hadron Collider (LHC) programme. In parallel, it pursues a strong interest in a physics programme with a high-luminosity upgrade of the LHC, and post-LHC facilities such as a linear electron-positron collider or a neutrino factory.
By Christmas 1990, Sir Berners-Lee had defined the Web’s basic concepts, the html, http and URL, and he had written the first browser/editor and server software. info.cern.ch was the address of the world's first web server, running on a NeXT computer at CERN. The world's first web page address provided information about the World Wide Web project.
On 19 December 1990, at noon, the beam from the Synchrocyclotron (SC) is stopped. At the end of the eighties the decision was taken to shut down the SC.
The ISOLDE programme should, however, continue at CERN and new facility will be built for an external beam from the Proton Synchrotron Booster.
In November 1990, Sir Tim Berners-Lee, together with CERN colleague, Robert Cailliau, submitted a formal management proposal for ‘WorldWideWeb: Proposal for a HyperText Project’.
(image: The basic principle of the RILIS technique: Two laser beams tuned to transitions between atomic levels - blue and yellow arrows - excite the atoms and a third beam induces the ionization)
The traditional ion sources used at ISOLDE were based on surface ionization and ionization in a plasma. These techniques together with different target matrices gave a large variety of beams for more than 20 years. A major step in improving the purity of and the number of available elements came in 1989 with a new technique based on laser ionization.
A combination of laser beams at wavelengths tuned to the sequence of atomic transitions enables highly efficient resonance excitation and ionization of selected atoms. Isotopes of other elements of the same mass do not interact with the laser radiation. This type of ion source is referred to as a Resonance Ionization Laser Ion Source (RILIS) and is a very powerful tool for the efficient and selective production of radioactive ion beams. The initial off-line RILIS development is then followed by its successful on-line application for laser ionization of ytterbium isotopes at ISOLDE-III on 10 October 1990.
(From left) Princess Margriet of the Netherlands, King Carl Gustav of Sweden, CERN Council President Josef Rembser, President François Mitterand of France, President Jean-Pascal Delamuraz of Switzerland, and Carlo Rubbia, Director-General of CERN at the time. This photo was taken on 13 November 1989 at the inauguration of the Large Electron–Positron (LEP) collider, an event which was attended by some 1500 guests including heads of state and ministers from all of CERN's Member States.
The four collaborations working on the LEP experiments presented their first results at a seminar organised at CERN. All of them confirmed that only three types of neutrinos exist, and hence there are only three generations of matter particles.
The first full-fledged physics run began on 20 September and continued for three months. During this time, the experiments each recorded around 30 000 Z particles, enough for the first data analysis to get under way.
With its 27-kilometre circumference, the Large Electron–Positron (LEP) collider was – and still is – the largest electron–positron accelerator ever built. LEP consisted of 5176 magnets and 128 accelerating cavities. CERN’s accelerator complex provided the particles and four enormous detectors, ALEPH, DELPHI, L3 and OPAL, observed the collisions.
LEP was commissioned in July 1989 and the first beam circulated in the collider on 14 July. The picture above shows physicists grouped around a screen in the LEP control room at the moment of start-up. Carlo Rubbia, Director-General of CERN at the time, is in the centre and former Director-General Herwig Schopper is on his left. For seven years, the accelerator operated at 100 GeV, producing 17 million Z particles, uncharged carriers of the weak force. It was then upgraded for a second operation phase, with as many as 288 superconducting accelerating cavities added to double the energy and produce W bosons, also carriers of the weak force. LEP collider energy eventually topped 209 GeV in the year 2000.
During 11 years of research, LEP and its experiments provided a detailed study of the electroweak interaction based on solid experimental foundations. Measurements performed at LEP also proved that there are three – and only three – generations of particles of matter. LEP was closed down on 2 November 2000 to make way for the construction of the LHC in the same tunnel.
Astrophysicists detected pulsed gamma-ray emissions from the Crab pulsar with energies that exceed 100 billion electronvolts (GeV). A pulsar is a highly magnetized, rotating neutron star that emits a beam of electromagnetic radiation. The Whipple Observatory 10-metre reflector, operating a 37-pixel camera, was used to observe the Crab Nebula in TeV gamma rays. The paper announcing their finding was published on July 1 1989.
The Crab pulsar is a rapidly spinning neutron star that exploded in a supernova in the year 1054 to leave behind the Crab Nebula. The Nebula rotates at about 30 times a second and the pulsar has a co-rotating magnetic field from which it emits beams of radiation.
Read more: "Observation of TeV gamma rays from the Crab nebula using the atmospheric Cerenkov imaging technique" – Astrophysical Journal, Part 1, 342 (1989) 379-395
Tim Berners-Lee made a first proposal for information management at CERN in March 1989 (no exact date is given). A later version was written in 1990, but this early document is particularly interesting because it includes annotations by his boss, Mike Sendall, whose general comment was ‘Vague but exciting…’! The project eventually grew to become the World Wide Web.
In this document Berners-Lee outlined the problems of losing information at CERN, the advantages of linked information and hypertext and the practical requirements of his idea. He proposed ‘a universal linked information system, in which generality and portability are more important than fancy graphics techniques and complex extra facilities. The aim of the project would be to allow a place to be found for putting any information or reference which one felt was important, and a way of finding it afterwards.’ With the help of Robert Cailliau and others he was able to make the dream a reality.
In March 1989, Sir Tim Berners-Lee, while working at CERN, wrote a proposal to develop a distributed information system. He resubmitted a slightly edited version in May 1990.
The excavation of the tunnel for the Large Electron–Positron Collider – Europe’s largest civil-engineering project prior to the Channel Tunnel – was completed on 8 February 1988. The two ends of the 27-kilometre ring came together with just one centimetre of error. The picture above shows a tunneling crew after completing a section of the tunnel between points 2 and 3 on the LEP ring.
With US President Ronald Reagan’s support, American physicists begin in-depth preparations to build the largest particle collider ever. The Superconducting Super Collider (SSC) – a circular accelerator with an 87-kilometre circumference – is designed to smash particles together at 40 TeV centre-of-mass energy. This would make the accelerator far more powerful than CERN's planned Large Hadron Collider (LHC). Construction begins in 1991 near Waxahachie, Texas. To some, the existence of the SSC project puts the need to build the LHC into doubt. Director-General Carlo Rubbia has to push to keep the LHC project alive.
Just after the big bang the universe was too hot and dense for the existence of familiar particles such as protons and neutrons. Instead, their constituents – the quarks and gluons – roamed freely in a "particle soup" called quark-gluon plasma.
In 1986 CERN began to accelerate heavy ions – nuclei containing many neutrons and protons – in the Super Proton Synchrotron (SPS) to study the possibility that quark gluon-plasma was more than just a theory. The aim was to "deconfine" quarks – set them free from their confinement within atoms - by smashing the heavy ions into appropriate targets.
The first experiments used relatively light nuclei such as oxygen and sulphur, and produced results consistent with the quark-gluon plasma theory, but no real proof. In 1994 a second generation of experiments began with lead ions, and by 2000 there was compelling evidence that a new state of matter had been seen.
Portugal joined CERN as a member state in 1986. The Laboratório de Instrumentação e Física Experimental de Partículas (LIP) was created at the same time to carry out all activities related to experimental particle physics, involving researchers from universities as well as LIP’s own scientific staff.
LIP's commitment to CERN programmes is presently based on LHC experiments and technologies (ATLAS, CMS and LCG), and the COMPASS collaboration. The Portuguese Institute for Nuclear Technologies (ITN) is leading the activity of a research team using the CERN ISOLDE facility.
The discovery of the W boson is so important that the two key physicists behind the discovery receive the Nobel prize in physics in 1984. The prize goes to Carlo Rubbia (pictured, left), instigator of the accelerator’s conversion and spokesperson of the UA1 experiment, and to Simon van der Meer (pictured, right), whose technology is vital to the collider’s operation.
The discovery of the W boson is a significant achievement in physics that further validates the electroweak theory. It also helps to secure the decision to build CERN’s next big accelerator, the Large Electron Positron Collider, whose job is to mass-produce Z and W bosons for further studies.
This photo shows one of the 4,500 visitors at CERN’s Open Day on 15 September 1984. The festivities, which marked the Organization’s 30th anniversary, also included a concert and a formal ceremony on 21 September. CERN’s team of historians put together an exhibition of archival documents, and a history seminar traced over three decades of achievement. Read all about the events in the November 1984 CERN Courier, or browse through the exhibition catalogue and official speeches here.
CERN and the European Committee for Future Accelerators (ECFA) hold a workshop in Lausanne, Switzerland and at CERN from the 21-27 March 1984. The event, Large Hadron Collider in the LEP Tunnel, marks the first official recognition of the concept of the LHC. Attendees consider topics such as what types of particles to collide and the challenges inherent to high-energy collisions. The image above shows one proposal from the workshop – adding the LHC in with the existing LEP machine – that was later scrapped.
CERN staff and their families were joined by numerous distinguished guests for the official ceremony that launched civil engineering work for the Large Electron-Positron (LEP) collider project on 13 September 1983. Speeches by Herwig Schopper (CERN’s Director-General) and Presidents François Mitterrand and Pierre Aubert were followed by an inaugural ceremony, then music and celebrations on the lawn.
With a circumference of 27 kilometres, LEP was the largest electron-positron accelerator ever built, and excavation of the LEP tunnel was Europe's largest civil-engineering project prior to the Channel Tunnel. LEP operated for 11 years from July 1989 until its closure on 2 November 2000 to make way for construction of the Large Hadron Collider (LHC) in the same tunnel.
The presidents of CERN’s two host countries, François Mitterrand of France and Pierre Aubert of Switzerland, symbolically broke the ground and laid a plaque commemorating the inauguration of the Large Electron–Positron collider (LEP) on 13 September 1983.
Although much of the necessary infrastructure for the new accelerator was already in place (such as CERN’s existing accelerator complex to pre-accelerate the electrons and positrons for LEP), many new facilities were needed. The most obvious of these was the 27-kilometre tunnel that housed the machine, along with the experimental halls and surface buildings. Transfer tunnels joining the Super Proton Synchrotron to LEP were also needed, as were buildings to house a linear accelerator (linac) and storage rings to make and accumulate electrons and positrons. Despite the huge scale of the undertaking, progress was impressive. By the end of 1984, the buildings for the linac and the electron–positron accumulator were complete and ten of the 18 access shafts had been excavated.
CERN is a centre for scientific research, but also a place for exchanges between science and other fields of human culture and understanding. The visit of His Holiness the Dalai Lama on 30 August 1983 provided just such an opportunity. In the morning he and his delegation of monks toured some of CERN’s facilities, including UA1, where the recent discovery of the W and Z bosons had taken place. After joining the visitors for lunch, some of CERN’s physicists gave short presentations on various aspects of CERN’s work, and a discussion explored the different viewpoints of Buddhists and physicists on a range of topics of mutual interest.
To maximize the use of the Synchrocyclotron (SC) beam time and to meet the requests from the growing physics community using ISOLDE, the ISOLDE collaboration decides to build a second isotope separator of ultra-modern design. The separator design uses a two-stage separation (one 60 degree and one 90 degree magnet) in order to obtain a very high resolution. The target is placed in the SC vault and after the second magnet, the ion beam enters the proton hall, which serves as the new experimental area.
ISOLDE III, is approved at the CERN Research Board session in June 1983 and the final approval to start building the new separator is taken on 10 November of the same year.
In a press conference on 25 January, CERN announces news of the discovery of the W boson to the world. The UA2 team reserves judgment at this stage but further analysis soon convinces them. From their results both teams estimate the boson's mass at around 80 GeV, which is in excellent agreement with predictions from electroweak theory.
In 1979, CERN decided to convert the Super Proton Synchrotron (SPS) into a proton–antiproton collider. A technique called stochastic cooling was vital to the project's success as it allowed enough antiprotons to be collected to make a beam.
The first proton–antiproton collisions were achieved just two years after the project was approved, and two experiments, UA1 and UA2, started to search the collision debris for signs of W and Z particles, carriers of the weak interaction between particles.
In 1983, CERN announced the discovery of the W and Z particles.The image above shows the the first detection of a Z0 particle, as seen by the UA1 experiment on 30 April 1983. The Z0 itself decays very quickly so cannot be seen, but an electron–positron pair produced in the decay appear in blue. UA1 observed proton-antiproton collisions on the SPS between 1981 and 1993 to look for the Z and W bosons, which mediate the weak fundamental force.
Carlo Rubbia and Simon van der Meer, key scientists behind the work, received the Nobel Prize in physics only a year after the discovery. Rubbia instigated conversion of the SPS accelerator into a proton-antiproton collider and was spokesperson of the UA1 experiment while Van der Meer invented the stochastic cooling technique vital to the collider’s operation.
The tension at CERN becomes electric, culminating in two seminars, from Carlo Rubbia (for UA1) on 20 January 1983 and Luigi Di Lella (for UA2) the following afternoon, both with the CERN auditorium packed to the roof. UA1 announces six candidate W events; UA2 announces four. The presentations are still tentative and qualified.
At the Topical Workshop on Proton-Antiproton Collider Physics in Rome from 12-14 January 1983, the first tentative evidence for observations of the W particle by the UA1 and UA2 collaborations is presented.
Out of the several thousand million collisions recorded, a handful give signals, which could correspond to the production of a W in the high-energy collision and its subsequent decay into an electron (or positron if the W is positively charged) and a neutrino
The return to CERN as a member state in 1983 marked the renaissance of high-energy physics in Spain. In the same year, a special programme for particle physics was created within the framework of the Spanish National Plan for research and development. The continuation of the original programme serves today to coordinate and fund most of the experimental and theoretical particle and astroparticle physics research in Spain.
A substantial part of the experimental high-energy physics activities in Spain is carried out at research institutes. Centro de Investigaciones Energeticas Medioambientales y Teconologicas (CIEMAT) in Madrid, Institut de Fisica d'Altes Energies (IFAE) in Barcelona and Consejo Superior de Investigaciones Científicas (CSIC) in Valencia play leading roles in detector construction and research-and-development activities. This effort is complemented by the activities of several other university groups such as Santander, Santiago de Compostela and Zaragoza, and research centres. Additional support to all groups is provided by the National Centre for Particle, Astroparticle and Nuclear Physics (CPAN). Several theory groups are very active in particle physics, studying a wide range of topics from phenomenology to mathematical physics. Spain also actively participates in most European Grid activities.
Spanish industry has participated in the construction of the LHC and its detectors, and has benefitted from an important transfer of technologies from CERN to Spain.
The first person outside CERN to be informed of the imminent discovery of the W boson is Margaret Thatcher, then Prime Minister of the United Kingdom, who paid a visit to CERN in August 1982. [See a video of the visit]. During her visit Thatcher asked the then Director-General of CERN Herwig Schopper to keep her updated on the progress of the search for the carriers of the weak force, the W and Z bosons.
In a confidential letter dated 20 December 1982, Schopper wrote:
"I am ever mindful of the promise I made on the occasion of your visit to CERN…that I would report to you immediately and directly on the day CERN obtained confirmed experimental evidence of the 'intermediate boson' (W+, W- and Z0) for which we are actively searching. …I am…pleased to inform you, in strict confidence, that the results recently obtained point to the imminence of such a discovery…"
Carlo Rubbia delays his departure to the Lisbon High Energy Physics Conference by a day so that on 10 July 1981, he is able to announce that the UA1 detector has seen its first proton-antiproton collisions. UA2 takes its first data in December this same year.
The Super Proton Synchrotron (SPS) accelerates its first pulse of antiprotons to 270 GeV. Two days later, with a proton beam orbiting in the opposite direction, there is the first evidence of proton-antiproton collisions. In August, the antiproton count reaches 109 and the UA1 calorimeter records some 4000 events. In October, the first visual evidence of the collisions is recorded in the streamer chambers of the UA5 detector (a precursor to UA2).
In the late 1970s physicists from CERN Member States were discussing the long-term future of high-energy physics in Europe. A new picture of fundamental processes – unification – was emerging and the Large Electron–Positron collider (LEP) would be the machine to study it. After a history built on proton accelerators, the idea of an electron–positron collider was a break with tradition for CERN. But since the results of electron and positron collisions are far easier to interpret than collisions between protons and antiprotons (which were on CERN’s more immediate horizon with the UA1 and UA2 experiments), the LEP proposal won through.
Presenting the project to CERN council, CERN Director-General Herwig Schopper reviewed the scientific justifications, budget and construction timetable for LEP. He concluded that:
Very rarely in the past has there been so much unanimity and so much consensus amongst the European scientific community on the validity of a research instrument.
The accelerator was formally approved on 22 May 1981.
The Intersecting Storage Rings produced the world’s first proton-antiproton collisions on 4 April 1981, paving the way for proton-antiproton collisions in the Super Proton Synchrotron (SPS), and the Nobel prize for Simon van der Meer and Carlo Rubbia.
The ISR proved to be an excellent instrument for particle physics. By the time the machine closed down in 1984, it had produced many important results, including indications that protons contain smaller constituents, ultimately identified as quarks and gluons.
Proton beams are injected and stored for the first time in the Antiproton Accumulator – a storage ring invented by CERN physicist Simon van der Meer where stochastic cooling produces intense antiproton beams. It took only two years from authorization of the machine to the announcement of first operation at the International Accelerator Conference at CERN, in July 1980. Within days, magnet polarities are reversed and antiprotons are injected and cooled.
Three physicists, Steven Weinberg, Abdus Salam and Sheldon Glashow, receive the Nobel prize in physics for proposing the electroweak theory. They believe that two of the four fundamental forces – the electromagnetic force and the weak force – are in fact different facets of the same force. Under high-energy conditions such as those in a particle accelerator, the two would merge into the electroweak force. But three hypothetical force-carrier particles described by the theory have yet to be confirmed in experiments: the W+, W- and Z0 bosons. These are heavy particles; so finding them would require an accelerator that could reach an unprecedented level of energy.
Official 25th anniversary celebrations were held on 25 June, but the fun and games happened on CERN’s real birthday, 29 September. As well as sports, sideshows, films, and Genevan Pipes and Drums, there was Happy Birthday, CERN, written and recorded for the occasion at Fermilab.
Verse three goes like this:
“Here's the toast we're proposing:
may your future be greater,
And the budget imposing for your
May your staff be effective and
your beams full of pep,
May you gain your objective of
constructing the LEP!”
If you can bear to read more, scroll down to page four here - and take a look at one of one of the star attractions at the same time: the Fire Brigade’s 20-metre rescue chute.
CERN issues a press release announcing the first storage of antiprotons. It reads:
Antimatter, in the form of antiprotons, has been stored for the first time in history.
This scientific first occurred at CERN, the European Organisation for Nuclear Research, at the end of July during tests conducted in view of using the SPS European accelerator as a colliding device between protons and antiprotons.
Several hundred antiprotons of 2.1 GeV/c were produced by protons from the PS accelerator and were kept circulating in a machine called ICE (Intial Cooling Experiment) for a period of 85 hours i.e. about 300, 000 seconds (3 × 105). The previous best experimental measurement of antiproton lifetime, acquired during bubble chamber experiments, was about 10-4 second, i.e. a ten-thousandth of a second.
CERN physicist Carlo Rubbia pulls together a team to put forward a proposal for an experiment code-named UA1, for "Underground Area 1", since its location on the SPS requires a large cavern to be excavated. The team grows to involve some 130 physicists from 13 research centres – Aachen, Annecy LAPP, Birmingham, CERN, Helsinki, Queen Mary College London, Collège de France Paris, Riverside, Rome, Rutherford, Saclay, Vienna and Wisconsin. On 29 June 1978, the CERN Research Board accepts the proposal for a huge "general purpose" detector to record proton-antiproton collisions at 540 GeV.
On 7 may 1977 Europe inaugurated the world’s largest accelerator – the Super Proton Synchrotron; you can read all about it in the CERN Courier.
But what was happening behind the scenes? Did you know that organising secretary, Miss Steel, set up a massive card index to keep track of the guests, entering all the details on 6,000 colour-coded cards? She also insisted on sending reply cards to the VIPs, even though treating them like ordinary mortals was considered infra dig; she said the higher you go in a hierarchy, the less legible signatures become, and she wanted to know who the replies came from. Logistics were further complicated by differing conceptions between the different countries as to what constituted an “official delegate”. Her unofficial report makes interesting reading too.
At 2.2 kilometres in diameter the Super Proton Synchrotron is Europe's largest particle accelerator. Commissioning of the accelerator begins in mid-March 1976 using beams of protons. Then on 17 June 1976 the SPS accelerates a beam of protons at its design energy of 400 GeV for the first time. The machine is ready to supply beams to experiments.
At the International Neutrino Conference in Aachen, Germany, (8-12 June 1976) physicists Carlo Rubbia, Peter McIntyre and David Cline suggest modifying the Super Proton Synchrotron (SPS) from a one-beam accelerator into a two-beam collider. The two-beam configuration would collide a beam of protons with a beam of antiprotons, greatly increasing the available energy in comparison with a single beam colliding against a fixed target.
Their paper on the subject, Producing Massive Neutral Intermediate Vector Bosons with Existing Accelerators is published in the conference proceedings the following year.
The Super Proton Synchrotron (SPS) became the workhorse of CERN’s particle physics programme when it switched on in 1976. The first beam of protons circulated the full 7 kilometres of the accelerator on 3 May 1976. The picture above shows the SPS control room on 17 June 1976, when the machine accelerated protons to 400 GeV for the first time. Research using SPS beams has probed the inner structure of protons, investigated nature’s preference for matter over antimatter, looked for matter as it might have been in the first instants of the universe and searched for exotic forms of matter. A major highlight came in 1983 with the Nobel-prize-winning discovery of W and Z particles, with the SPS running as a proton-antiproton collider.
The SPS operates at up to 450 GeV. It has 1317 conventional (room-temperature) electromagnets, including 744 dipoles to bend the beams round the ring. The accelerator has handled many different kinds of particles: sulphur and oxygen nuclei, electrons, positrons, protons and antiprotons.
New experiments are installed at ISOLDE II and placed at the three main beam-lines. The photo shows the underground hall UR8 on April 6 1976, which only housed experimental installations. The control desk could be found one floor above.
A trip to China in September 1975 helped pave the way for increased contact between the scientific communities. Scientists from the People's Republic of China had visited CERN in July 1973, and the reciprocal invitation two years later included social and scientific exchanges plus the traditional group photo at the National People’s Congress Palace. The schedule underwent several changes, you can see a draft here.
The visitors assured their hosts that Chinese physicists and engineers would be welcome at CERN for longer periods. ”At first, their reaction was polite agreement as to the desirability of such visits,” reported Viktor Weisskopf. “On September 14, we were received by a high government official: Wu Lein-fu, Vice Chairman of the Standing Committee of the National Congress [centre front of photo]. This man supported the proposal of extended visits of Chinese physicists and engineers to CERN, by quoting a Chinese proverb: "One eye is better than a hundred ears”. I had the impression that, from then on, the Chinese physicists talked much more about extended visits to CERN." You can read more about it in the October 1975 issue of the CERN Courier.
A Data Handling Division report by Philipe Bloch states:
Around the CERN sites more than 150 computers of widely varying sizes are installed. They vary from small mini-computers (PDP8, HP2115A) via larger mini's and control computers (PDP11/45, HP4100, Nord-10, IBM1800, Modular One, Ferranti Argus 500) over medium sized computers such as PDP-10, IBM-360/44, CII 10070 and CDC 3200 to very large computers (CDC 6600, CDC 7600) in the Computer Centre itself. Many mini-computers are used by experimenters for data collection but accelerator control, remote batch stations and process control application use most of these. The medium sized computers are normally dedicated to particular types of processing for individual groups or divisions: measurements of bubble chamber pictures (CDC 3200, ERASME on the PDP-10), support for data collection for the OMEGA spectrometer and the Split Field Magent (CII 10070).
The Computer Centre is part of the Data Handling Division and provides a general purpose scientific computing service to both Laboratories... About 700-800 different users run approximately 15,000-20,000 jobs per week on the main computers and mount about 4000 tape reels from a total tape library of more than 6000 reels. Remote batch and terminal services as well as high-speed data links and a delivery service make computing easily accessible practically everywhere on the site round the clock.
A few months after the signature of the agreement giving the go-ahead for the expansion of CERN into French territory, work began on the Super Proton Synchrotron (SPS). Two years later, on 31 July 1974, the Robbins tunnel-boring machine excavating the SPS tunnel returned to its starting point (see photograph). It had excavated a tunnel with a circumference of 7 kilometres, at an average depth of 40 metres below the surface. The tunnel straddled the Franco-Swiss border, making the SPS the first cross-border accelerator. More than a thousand magnets were needed to equip the ring. The civil engineering and installation work was completed in record time after only four years.
A team photo celebrates the completion of the SPS tunnel in July 1974. The Super Proton Synchrotron (SPS) was the first of CERN’s giant accelerators. It was also the first cross-border accelerator. Excavation took around two years, and on 31 July 1974 the Robbins tunnel-boring machine returned to its starting point having crossed the Franco-Swiss border and excavated a tunnel with a circumference of 7 kilometres and an average depth of 40 metres below the surface.
The SPS was commissioned in 1976, and a highlight of its career came in 1983 with the announcement of the Nobel prize-winning discovery of W and Z particles.