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news feature The show CERN goes on CERN, the centre for particle physics in Europe, has been smashing its way through the subatomic world for the past 50 years. Alison Abbott finds out what’s in store for the future. uring CERN’s routine maintenance shut-down in 1999, acrobats and Dmime artists turned one of the vast halls within the laboratory’s 27-kilometre tunnel into a stage. Light and shadows played around the nine-storey cavern, illuminating a poetic ballet of aerial gymnastics. On ropes, trapezes and ledges, the performers enacted Paul Dirac’s creative struggle with his 1920s theory of antimatter and his pessimistic belief that such theories could never be con- firmed experimentally. In the show’s final scene, the huge backdrop parted to reveal the DELPHI experiment, where for the past decade CERN physicists have been observing Where art and science meet: the DELPHI experiment takes a starring role in a dance about antimatter. collisions between electrons and positrons, their antimatter counterparts. deep and fundamental questions with which the lab over the past half-century, and The show symbolized everything that the laboratory concerns itself — What is our exchanged views in its famous cafeteria, and CERN has achieved in its first 50 years (see Universe made of? How did it arise? — but they’ll wistfully recall a touch of magic. “The ‘50 years of CERN’, below). The lab’s raison also in the idealism of its scientific approach, intense but non-aggressive scientific style,the d’être has been to develop increasingly and the charm of its working atmosphere. extraordinary variety of international scien- sophisticated machines to provide answers Founded in the ruins of post-war Europe tists — I loved it, and it completely changed to the questions that plague theorists seeking as a cross-border partnership to recreate the my perspective,”says Harry Nelson, a particle fundamental truths about the Universe. base in particle physics destroyed by the Sec- astrophysicist at the University of California, If science ever comes close to poetry, it ond World War,CERN continues to live by its Santa Barbara,who spent three years at CERN does here, in the ugly sprawl of CERN’s flat- philosophy that science has no borders. in the late 1980s as a postdoc.“And it’s a place roofed buildings overlooked by the beautiful Ask any of the tens of thousands of physi- where some really great discoveries have been Jura mountains near Geneva. Not just in the cists from 80 countries who have worked at made.I sometimes dream of going back.” LEFT) CERN/SPL;(FROM CERN 824 NATURE | VOL 430 | 19 AUGUST 2004 | www.nature.com/nature © 2004 Nature Publishing Group news feature But will the accolades still be coming in CERN when CERN celebrates its 75th anniversary? The technical demands of particle physics ARKER/SPL have increased at an alarming rate — D. P much to the dismay of governments that have to pay for machines that now cost bil- lions. As purse-strings tighten, stresses have emerged in the traditionally cohesive inter- national particle-physics community. The community is expected to announce its technology choice for the next big machine by the end of this week. Despite the CERN’s director-general, Robert Aymar, is responsible for ensuring the success of the lab’s next big display of unity, behind the scenes CERN is machine, the Large Hadron Collider, which will hunt the Higgs boson (simulated, right). gambling that an alternative technology it is developing will, at some future date, become and then capture the resulting fireworks with great discoveries, the heavy W and Z particles, a scientifically superior option. cleverly designed detectors. The properties of carriers of the weak nuclear force, just five newly discovered particles fed back into theor- months apart in 1983. This established CERN Early days ies that became collectively known as the stan- as a world leader,and won Rubbia and van der For its opening act, in the early 1950s, the dard model of the structure of matter. Meer the 1984 Nobel prize in physics (see mood was upbeat. The concept of CERN was CERN’s first machine, the Synchro- ‘Winning personalities’,overleaf). first proposed by the French physicist and Cyclotron, accelerated a beam of protons up Nobel prizewinner Louis de Broglie at the to energies of 600 million electron volts (eV) Upping the ante 1949 European Cultural Conference in Lau- and smashed it into a fixed target. This rela- CERN’s most recent machine, the Large sanne. Five years later, 12 states signed the tively low collision energy was sufficient to Electron Positron (LEP) collider, whose 27- founding treaty, making CERN the first post- generate pions, unstable particles formed kilometre tunnel straddles the Franco-Swiss war organization to include West Germany from a mixture of matter and antimatter. border, hurled a beam of electrons into a as a member. CERN now has 20 member The CERN pioneers were thrilled to watch beam of positrons. Unlike protons, elec- states, and although the Soviet Union never pions decay into electrons and neutrinos in trons have no internal structure, so their joined, many of its scientists worked there line with predictions from the standard collisions are less messy, although their alongside Westerners during the cold war. model. Each new machine took collision lighter mass means that they cannot reach Back in 1954, the frontier of knowledge energies higher, revealing new particles with such high collision energies. Still, LEP was was nuclear, not particle, physics, as CERN’s properties predicted by the standard model. able to better characterize particles that had full name,the Conseil Européen CERN’s second act opened been discovered with the SPS, and was only pour la Recherche Nucléaire, “The non-aggressive in the early 1980s with techno- switched off in 2000 to make room in the reflects. Theorists recognized scientific style, the logical innovation. In the late tunnel for its successor, the Large Hadron three fundamental forces gov- variety of international 1960s, CERN accelerator physi- Collider (LHC). Until the LHC starts oper- erning atomic matter — the scientists. I loved cist Simon van der Meer had ating in July 2007, only a handful of small strong nuclear interaction, the CERN, and it developed a key technology, experiments are running at the lab. weak nuclear interaction and completely changed called stochastic cooling, for As the machines get bigger, so do the col- the electromagnetic force — my perspective.” storing antimatter particles.This laborations.Rubbia’s W and Z team involved but had little idea of how to inte- — Harry Nelson made it possible to collide a beam 150 scientists. Today, teams at accelerator grate them in a way that would of protons precisely with a beam labs often number 500. The biggest experi- explain the physical Universe. of anti-protons travelling in the opposite ment planned for the LHC, called ATLAS, But they had some idea about what was direction. If both beams are accelerated to involves 2,000 physicists. missing. Although only protons, neutrons similar speeds,the collision energy is doubled. Although the numbers may sound fright- and electrons had been described as the basic In the 1970s, the experimental physicist ening, those working in big collaborations constituents of an atom,cosmic-ray research Carlo Rubbia, who held joint positions at say that individuals are not condemned to had shown that there were a lot more exotic CERN and Harvard University, championed anonymity. Michel Spiro, now director of particles, with names such as ‘pions’ and this high-stakes technology. And in 1981, the National Institute of Nuclear and Particle ‘muons’,to be discovered. CERN upgraded its Super Proton Synchro- Physics in Paris, remembers working on The best way to make discoveries was to tron (SPS) into a collider able to reach ener- the W and Z experiment: “Rubbia was smash a beam of charged particles,such as pro- gies of up to 500 billion eV. number one, of course, but I made my own (FROM LEFT) D.(FROM PARKER/SPL; CERN tons or electrons, into a target at high speed With its souped-up SPS,CERN scored two contribution which was recognized by my NATURE | VOL 430 | 19 AUGUST 2004 | www.nature.com/nature 825 © 2004 Nature Publishing Group news feature colleagues.” And it all happened “in an theories such as ‘super- atmosphere of thrilling enthusiasm”, he strings’ and ‘extra dimen- CERN adds,“because we knew that the experiment sions’to try to explain how could be a breakthrough for particle physics”. the Universe may fit In the ATLAS collaboration,experiments together, but they are very are split into subprojects. Karlheinz Meier speculative,” says John of the University of Heidelberg, a principal March-Russell, a theoreti- investigator in ATLAS,says his own ‘Trigger’ cal physicist at the Univer- project, which will design an electronics sys- sity of Oxford, UK, who tem to filter out the most interesting physics spent four years at CERN. from LHC collisions, involves only 30 physi- Like his colleagues, he cists from five institutes.“It’s sort of like the hopes that the LHC will old days,”he says.“The group is small and we help reduce speculation. are getting to know each other very well.” “Knowing more about Brain food: cafe society is at the heart of CERN’s relaxed atmosphere. Project teams are scattered geographi- the Higgs and supersym- cally, but share information over the World metry will let us pose the Wide Web, invented at CERN for this pur- next questions more sensi- pose.In future they will use the Grid,a global bly,” says Frank Wilczek, a supercomputing network that CERN is theoretical physicist at the Q.