Collider Part 5

The next phase in planning the SSC took place through a team called the Central Design Group (CDG), situated at Lawrence Berkeley National Laboratory and also led by Tigner. Several different labs, including the Berkeley Lab, Brookhaven, Fermilab, and the Texas Accelerator Center, a research inst.i.tute established by collider expert Peter McIntyre, were recruited to investigate the various superconducting magnet designs. The majority of the group supported the strong-field magnet that would require a ring about fifty-two miles in circ.u.mference, as opposed to the weak-field design that would necessitate a ring up to a hundred miles long. It would be hard enough to find enough land to support the smaller ring.

By late 1986, the SSC design had been submitted to the DOE and the major labs were united in their support. Because of the projected multibillion-dollar cost for the project, to move forward the approval of President Ronald Reagan, the American leader at the time, was required. On the face of it, that would seem to be a hard sell, given that the federal budget was already stretched through various military and scientific programs. Expensive projects at the time included the Strategic Defense Initiative (more commonly known as "Star Wars") for developing missile-interception systems and a program to establish an international s.p.a.ce station. How could the SSC carve out its own piece of a shrinking pie?

Luckily for the prospects of gaining approval, if there was a frontier to be conquered or an enemy to be defeated, Reagan believed in taking major risks. Famously, long before becoming a politician, he played the role of a football player for an underdog team in the film Knute Rockne, All American Knute Rockne, All American. Like his character George Gipp, better known as "the Gipper," optimism and determination steered his judgments. The SSC was a project on the scientific frontier that represented a means of remaining compet.i.tive with Europe. That was the angle its proponents emphasized to win over Reagan's support.

A DOE official asked Lederman if he and his staff could produce a ten-minute video for the president about the questions in high-energy physics the SSC could potentially resolve. To appeal to Reagan's cowboy spirit, Lederman decided to emphasize the frontier aspects of the research. In the video, an actor playing a curious judge visits a lab and asks physicists questions about their work. At the end he remarks that although he finds such research hard to comprehend, he appreciates the spirit behind it, which "reminds [him] of what it must have been like to explore the West."2 Apparently the SSC advocates' arguments were persuasive, because Reagan was deeply impressed. Members of his cabinet, concerned about the fallout from the project's asteroidlike impact on the budget, ardently tried to intercept it. With all of their strategic defenses, however, they could not shoot it down.

At Reagan's January 1987 announcement that he would support the SSC, he took out an index card and recited the credo of writer Jack London: I would rather be ashes than dust, I would rather my spark should burn out in a brilliant blaze, Than it should be stifled in dry rot.

I would rather be a superb meteor, With every atom of me in magnificent glow, Than a sleepy and permanent planet.

3.

After reading the credo, Reagan mentioned that football player Ken Stabler, known for coming from behind for victory, was once asked to explain what it meant. The quarterback distilled its sentiments into the motto, "Throw deep!"4 Surely the erstwhile "Gipper"-turned-president would aim no lower. The SSC would move ahead, if he could help it. Surely the erstwhile "Gipper"-turned-president would aim no lower. The SSC would move ahead, if he could help it.

At a White House ceremony the following year, Reagan heralded the value of the SSC, saying, "The Superconducting Super Collider is the doorway to that new world of quantum change, of quantum progress for science and for our economy."5 Following Reagan's endors.e.m.e.nt came the battle for congressional approval, which would not be so easy. Many members of Congress balked at the idea of the United States carrying the ball alone. Consequently, the SSC was marketed as an international enterprise, involving j.a.pan, Taiwan, South Korea, various European nations, and others. Newsweek Newsweek described selling the project this way: "The DOE promised from the start that other nations would help bankroll the SSC. That pledge has greased the project's way through many sticky budgetary hearings." described selling the project this way: "The DOE promised from the start that other nations would help bankroll the SSC. That pledge has greased the project's way through many sticky budgetary hearings."6 Significant international support was hard to come by, however. The Europeans in particular were naturally more interested in seeing CERN succeed than in supporting an American enterprise. That's around the time the Large Hadron Collider (LHC) project was first proposed-clearly a higher priority for Europe.

A New York Times New York Times editorial on May 20, 1988, argued that any American funding toward the SSC would be better spent contributing toward the LHC instead: editorial on May 20, 1988, argued that any American funding toward the SSC would be better spent contributing toward the LHC instead: This is a tempting but dangerous initiative because funds to pay for it almost certainly would be stripped from other physics research. . . . The field is of high intellectual interest, and it would be a sad day if the United States did not remain a major player. But European physicists have shown how an existing collider ring at Geneva could be upgraded to within probable reach of the Higgs boson. Buying into the European ring would be cheaper.7 By mid-to-late 1988, Congress had allocated $200 million toward the SSC. Proceeding with caution, it mandated that the money could be used only for planning and site selection. Because an election was imminent, funds for the actual construction would be left to the consideration of the next administration.

Once Congress offered a kind of yellow light for the project to move forward cautiously, the politics behind the venture became even more intense. Many depressed regions salivated over the potential for jobs. Which state would be lucky enough to acquire what the Times Times called "a $6 billion plum"? called "a $6 billion plum"?8 To be fair, the compet.i.tion to find a suitable site was judged by a committee established by the respected and politically neutral National Academy of Sciences and National Academy of Engineering. Of the forty-three proposals submitted from twenty-five states, including seven from the state of Texas alone, the committee narrowed them down to seven. The Lone Star State was clearly the most eager; its government established the Texas National Research Laboratory Commission (TNRLC) well in advance and sweetened the pie by offering $1 billion toward the project from its own budget. What better place to think big than in Texas? Its submission was so hefty-rumored to weigh tons-it was hoisted to the DOE office by truck.9 In November 1988, after considering the relative merits of the finalists, the DOE announced that Ellis County, Texas-a flat, chalky prairie region with little vegetation except for gra.s.ses, shrubs, mesquite, and cactus-was the winning location. In November 1988, after considering the relative merits of the finalists, the DOE announced that Ellis County, Texas-a flat, chalky prairie region with little vegetation except for gra.s.ses, shrubs, mesquite, and cactus-was the winning location.

By odd coincidence, the site location announcement occurred just two days after a Texan-then Vice President George Herbert Walker Bush-was elected president. The DOE selection group a.s.sured the public that politics played no role in the decision. Through a spokesperson, Bush a.s.serted that he had no involvement in the process and that he found out about the choice when everyone else did.10 With the choice of a completely undeveloped site in Texas, many supporters of Fermilab, which had also bid, were left fuming. Fermilab already had much of the infrastructure in place to support an expanded mission; a new location would require starting from scratch with all new staff, buildings, and equipment. In particular, the Tevatron could have been adapted, like the SPS at CERN, to serve as a preaccelerator for the protons entering the collider. "If it was at Fermilab, it would have existed now,"11 said Brookhaven physicist Venetios Polychronakos, who was involved in planning an SSC experiment. said Brookhaven physicist Venetios Polychronakos, who was involved in planning an SSC experiment.

Some feared a brain drain from Fermilab, with top researchers finding new positions in Texas. Lederman, who had a key stake in both inst.i.tutions as Fermilab's director and one of the SSC's original proposers, expressed mixed feelings. He antic.i.p.ated a "certain loss of prestige" for his own lab.12 However, he expected that it would remain a premier research facility-at least during the years when the SSC was under construction. However, he expected that it would remain a premier research facility-at least during the years when the SSC was under construction.

Soon after its bid was accepted, the Texas state government, through the TNRLC, a.s.sembled a parcel of almost seventeen thousand acres near Waxahachie. For the land of Pecos Bill, that was just a mere pasture. The TNRLC also arranged for environmental studies and administered a research and development program to support the lab. The state's commitment to the project remained steadfast until the end.

The federal commitment to the project was murkier, as there were many clas.h.i.+ng forces involved. Congress, the DOE, and research physicists themselves each had different interests, which were sometimes at odds. Although Tigner's CDG performed the bulk of the original planning for the project, when it came time to move forward with constructing the collider and setting up the lab, the group was bypa.s.sed in favor of the Universities Research a.s.sociation (URA)-a consortium that managed Fermilab and with which the DOE felt comfortable working. Tigner was seen as a "cowboy in the Wilson tradition" 13 13 and as potentially having difficulty bending to the demands of Congress and the DOE. Thus, the URA instead chose a relative newcomer, Harvard physicist Roy Schwitters, to become lab director. After serving briefly under Schwitters as deputy director, Tigner stepped down in February 1989 and returned to Cornell. Sadly, with his resignation, the construction of the SSC would need to proceed without his vital technical experience, including the five years he spent helping design the accelerator. and as potentially having difficulty bending to the demands of Congress and the DOE. Thus, the URA instead chose a relative newcomer, Harvard physicist Roy Schwitters, to become lab director. After serving briefly under Schwitters as deputy director, Tigner stepped down in February 1989 and returned to Cornell. Sadly, with his resignation, the construction of the SSC would need to proceed without his vital technical experience, including the five years he spent helping design the accelerator.

As scientific historian Michael Riordan has pointed out, Schwitters and the URA sharply departed from prior practice by integrating private industrial contractors into the decision-making process. 14 14 Before the SSC, accelerator laboratories were planned solely by research physicists-who would employ technicians if needed for particular tasks. As we've seen, for instance, Wilson designed almost all aspects of Fermilab himself. Schwitters had a different philosophy, involving industrial representatives as well as academics to solve the engineering challenges a.s.sociated with building what would have been the world's most formidable scientific apparatus. Among these were corporations heavily involved in the defense and aeros.p.a.ce industries, and for whom it was their first exposure to high-energy physics. Many of the industrial workers switched jobs because of military cutbacks due to the end of the cold war. Because they were used to a certain mind-set, the lab a.s.sumed some of the secretive aspects of a defense inst.i.tute. Moreover, some of the established physicists felt that they couldn't handle the scientific demands. These factors, as Riordan noted, created a clash of cultures that alienated many of the experienced researchers and made it hard to recruit new ones. Before the SSC, accelerator laboratories were planned solely by research physicists-who would employ technicians if needed for particular tasks. As we've seen, for instance, Wilson designed almost all aspects of Fermilab himself. Schwitters had a different philosophy, involving industrial representatives as well as academics to solve the engineering challenges a.s.sociated with building what would have been the world's most formidable scientific apparatus. Among these were corporations heavily involved in the defense and aeros.p.a.ce industries, and for whom it was their first exposure to high-energy physics. Many of the industrial workers switched jobs because of military cutbacks due to the end of the cold war. Because they were used to a certain mind-set, the lab a.s.sumed some of the secretive aspects of a defense inst.i.tute. Moreover, some of the established physicists felt that they couldn't handle the scientific demands. These factors, as Riordan noted, created a clash of cultures that alienated many of the experienced researchers and made it hard to recruit new ones.

Despite these internal tensions, during the first Bush administration, the SSC benefited from strong federal support. Familiar with the Texas landscape due to his years as a businessman and politician in that state, President Bush considered the SSC a national scientific priority and pressed Congress each year to fund it. The DOE distributed particular tasks such as building and testing detectors throughout almost every state, offering politicians around the county further incentive to favor it.

The program even survived a doubling of its estimated completion cost to a whopping $8 billion, announced in early 1990. This came about when engineering studies forced a major redesign of the project due to issues with the magnets and other concerns.

Superconducting magnets are in general extremely delicate instruments. The stronger a magnet's field, the greater its internal forces and the higher the chance that its coil and other parts will subtly oscillate. Vibrations cause heating, which can ruin the superconducting state and weaken or destroy the magnets. At 6.5 Tesla (the metric unit of magnetism)-more than 50 percent stronger than the Tevatron's field-the SSC's magnets were very much at risk. To minimize tiny movements, the magnets included carefully placed steel clamps. Getting them to work effectively was a matter of trial and error. In an important preliminary test of twelve magnets, only three pa.s.sed muster. Designers struggled to improve the performance.

Another question concerned the size of the magnets' openings. Smaller apertures were cheaper but entailed a greater risk to the streams of protons pa.s.sing through. Any misalignment could reduce the rate of collisions and sabotage the experiment. Ultimately, after considerable discussion, the SSC administration decided to enlarge the magnet openings to allow more room for error.

Other design changes made at that time included increasing the ring circ.u.mference to fifty-four miles and doubling the proton injection energy (the energy protons are accelerated to before they enter the main ring). All of these modifications forced the bill sky high. Although some members of Congress became livid when learning about the huge increase in the cost, the general reaction at that time was to increase oversight rather than close down the project. Construction funds started to flow, and the lab began to take shape starting in the fall of 1990.

As planned, the SSC was to have a succession of accelerators boosting protons to higher and higher energies before they would enter the enormous collider ring. These consisted of a linear accelerator and three synchrotrons of increasing size: the Low Energy Booster, the Medium Energy Booster, and the High Energy Booster. Tunnels for the linear accelerator and the smallest synchrotron were the first to be excavated.

Boxy structures, to support future operations underground, sprang up like prairie gra.s.s along the flat terrain, including the Magnet Development Lab, the Magnet Test Lab, and the Accelerator Systems String Test Center. These were facilities for designing, building, and testing the various types of superconducting magnets needed for the project. Two large companies, General Dynamics and Westinghouse, took on the task of building the thousands of dipole magnets that would steer the protons, like roped-in cattle, around what would have been the largest underground rodeo in the world.

Meanwhile, drawn by the prestige of contributing to a kind of Manhattan Project for particle physics, or simply finding a good-paying position, more than two thousand workers relocated to Texas. The lure of potentially finding the Higgs boson or supersymmetric companion particles enticed many an adventurous physicist to venture south of glittery Dallas and try his or her luck with collider roulette. For researchers who already had thriving careers, it was a significant gamble. Some took leave from their full-time positions; others gave up their old jobs completely with hopes of starting anew.

In the tradition of colliders supporting a pair of major detectors, with collaborations lined up behind these, two groups' proposals were approved for the SSC. The first, called the SDC (Solenoidal Detector Collaboration), involved almost a thousand researchers from more than a hundred inst.i.tutions worldwide and was headed by George Trilling of the Berkeley Lab. Its general-purpose detector was designed to stand eight stories high, weigh twenty-six thousand tons, and cost $500 million. The target date for it to start collecting data was fall 1999-offering hope of finding the Higgs before the toll of the millennial bells.

The second group, called GEM (Gammas, Electrons, and Muons), was led by Barry Barish of Caltech, an accomplished experimentalist with a stately beard and shoulder-length silver hair, along with liquid argon calorimetry coinventor William Willis of Columbia University, and a humongous cadre of researchers. Their project involved a detector specially fas.h.i.+oned for pinpoint measurements of electrons, photons, and muons. GEM was supposed to be located around the ring from the SDC at a different intersection point, collecting data independently, like competing newspapers housed in separate city offices.

Unfortunately, neither of these detectors ever had a chance to taste flavorful particles. As the SSC project rolled through the early 1990s, it acc.u.mulated more and more opposition-not just from politicians dismayed that it would break the budget but also from fellow physicists in fields other than high energy. Most branches of experimental physics don't require $8 billion budgets, yet can still yield groundbreaking results.

Take for example high-temperature superconductivity. In the 1980s, Swiss physicist Karl Muller and German physicist Johannes Bednorz, working with reasonably priced materials in the modestly sized (compared to CERN or Fermilab at least) complex of IBM's Zurich Research Laboratory, revolutionized physics with their discovery of a ceramic compound that could conduct electricity perfectly at temperatures higher than previously known superconductors. Other experiments in various labs, including work by Paul Chu at the University of Houston, turned up substances with even higher transition temperatures. Although these ceramic superconductors still need to be quite cold, some maintain their properties above the temperature of liquid nitrogen. Immersing a material in liquid nitrogen is far cheaper than the drastic methods used to create the near-absolute-zero superconductors once believed to be the only types. Therefore not only did Muller and Bednorz's finding come with a much cheaper price tag than, say, the top quark, it also led to cost saving for future research and the potential for more widespread applications of superconductivity.

Because discoveries related to material properties bear more directly on people's lives than does high-energy physics, many researchers in these fields, such as Cornell physicist Neil Ashcroft, have argued that they deserve at least as much support. "Things are out of whack," he said. "Condensed-matter physics is at the heart of modern technology, of computer chips, of all the electronic gadgets behind the new industrial order. Yet relative to the big projects, it's neglected."15 Another leading critic of "big science," who was skeptical about channeling so much funding into the Super Collider, was Arno Penzias, codiscoverer of the cosmic microwave background. Penzias said, "One of the big arguments for the S.S.C. is that it will inspire public interest in science and attract young people to the field. But if we can't educate them properly because we've spent our money on big machines instead of universities, where's the point? As a nation we must take a new look at our scientific priorities and ask ourselves what we really want."16 On the other hand, who could antic.i.p.ate what would have been the long-term spin-offs of the SSC? In the past, some discoveries that seemed very theoretical at the time, such as nuclear magnetic resonance, have ended up saving countless lives through enhanced techniques for medical imaging and treatment. But since n.o.body had a crystal ball for the SSC and its potential applications, its critics painted it as just big and expensive.

The rising crescendo of arguments against "big science" and in support of smaller, less expensive projects jived well with growing congressional sentiments that the SSC was getting out of hand. Given that Congress was promised that substantial foreign contributions would fill out the SSC's budget, when these failed to materialize, many members were understandably miffed. Some didn't think that Schwitters and the DOE under Secretary of Energy James Watkins were managing the project effectively. Still, it came as a surprise when in June 1992 the House of Representatives voted 232-181 in favor of a budget amendment that would end the project.17 Only the Senate's support for the SSC temporarily kept it alive. Only the Senate's support for the SSC temporarily kept it alive.

In the spirit of former senator William Proxmire's "Golden Fleece Awards" for alleged government boondoggles, many of those who favored terminating the SSC painted it as a wasteful endeavor that would benefit only a small group of eggheads. In times of tight budgets, they wondered, why channel billions of dollars into cras.h.i.+ng particles together to validate theories rather than, say, blasting away at the all-too-real federal deficit behemoth?

"Voting against the SSC became at some point a symbol of fiscal responsibility," said its then a.s.sociate director Raphael Kasper, who is currently vice president of research at Columbia. "Here was an expensive project that you could vote against."18 In January 1993, Bill Clinton succeeded Bush as president. Without the Texas connection, a key strand of the SSC's support dissolved. Although Clinton indicated that he backed the project, particularly in a June letter to the House Appropriations Committee, he advocated extending the time line for three extra years to reduce the annual impact on the federal budget. Postponing the SSC's targeted opening date (to 2003) made it seem an even riskier venture, however, because it could well have been obsolete by the time it went on line. What if the Tevatron had found the Higgs boson by then?

Once the collider lab's antic.i.p.ated costs rose to approximately $10 billion, largely because of the pus.h.i.+ng back of its schedule, it was only a matter of time before an increasingly frugal Congress signed a do-not-resuscitate order. A House of Representatives vote on October 19, 1993, denied by a two-to-one margin a funding bill that would have supported further construction. Instead, the SSC's annual appropriation was directed to moth-ball the part of the facility that had already been built. By then $2 billion had already been spent and more than one-quarter of the project was complete-all for naught. The tangible result of a decade of planning and hard work would just be boarded up and shrouded in dirt. Requiescat in pace.

The cancellation of the SSC did, in the short term, save federal money. Along with many other cost-cutting measures, the federal budget would be balanced by the end of the decade. (Ironically, in the 2000s, the deficit would skyrocket again, making all of the cost cutting moot!) Yet, what is the long-term price of a national decline in scientific prestige? Skipping the moon landings, eschewing the robotic exploration of Mars, and abstaining from telescopic glimpses at the swirling mists of ancient galaxies would have each cut government expenses, too-while extinguis.h.i.+ng the flames of our collective imagination. If it is a choice between science and sustenance, that's one thing, but surely our society is rich enough to support both. It remains to be seen whether the United States will ever resume its pioneering mantle in high-energy physics. Thus in retrospect, many see the abandonment of what would have been the premier collider in the world as a grave error.

According to Fermilab physicist William John Womersley, "The SSC has cast a very long shadow over high-energy physics and big science in general. We're still dealing with the legacy."19 In the aftermath of the closure, those who took the career risk and moved down to Texas for the SSC met with varying degrees of disappointment. Some regrouped, sent out their resumes (or were recruited), and managed to find new positions in other labs or universities. For the experienced physicists, finding an academic position was hard, because not many universities wished to hire at the senior level, and the closure of the SSC reduced the need for professors in the high-energy field. A survey taken one year after the closure found that while 72 percent of those in the SSC's Physics Research Division had found employment, only 55 percent of those positions were in high-energy physics.20 Other workers, who had laid down deep roots in Texas and didn't want to leave, either found other types of jobs or simply retired early. A few stayed to help sell off the equipment and a.s.sist in attempts to convert the site to alternative uses.

Given all of the time and energy that went into a.s.sembling the land, digging the tunnels, and constructing the buildings, it is remarkable that the site has yet to be put to good use. The federal government transferred the property to the state of Texas, which in turn deeded it to Ellis County. For more than fifteen years, the county has tried in vain to market the structures, particularly the former Magnetic Development Laboratory. Like d.i.c.kens's forlorn spinster, Miss Havisham, the relic building is a jilted bride frozen in time with no interested suitors. An agreement to convert it into a distribution center for pharmaceutical products fell through, and informal plans to house an ant.i.terrorism training base never materialized. In 2006, trucking magnate J. B. Hunt's plans to use it as a data center were abandoned upon his death.21 It did, however, play a background role in a straight-to-video action flick, It did, however, play a background role in a straight-to-video action flick, Universal Soldier II Universal Soldier II. 22 22 To mention another has-been, the Norma Desmond of labs finally had its close-up. To mention another has-been, the Norma Desmond of labs finally had its close-up.

Though it's instructive to ponder what could have been in hypothetical scenarios about alternative choices, in truth physicists can't afford to wallow in disappointment. An energetic frontier is ripe for exploration and there's no time for looking back. Leaving the plains and pains of Texas behind, in the late 1990s the American particle physics community regrouped and headed either north to Illinois, for renewed efforts at the Tevatron, or across the ocean to the cantoned land where cubed meat and melted cheese deliciously collide. After all, Geneva, Switzerland, has distinct charms, some of which Lederman described well. Comparing it to Waxahachie, he wrote, "Geneva . . . has fewer good rib restaurants but more fondue and is easier to spell and p.r.o.nounce."23 Humanity's best chance of finding the Higgs boson and possibly identifying some of the lightest supersymmetric companion particles now rests with the Large Hadron Collider. Though it will crash particles together at lower energies than the SSC was supposed to-14 TeV in total instead of 20 TeV-most theoretical estimates indicate that if the Higgs is out there the LHC will find it. If all goes well, modern physics will soon have cause for celebration.

8.

Cras.h.i.+ng by Design Building the Large Hadron Collider

The age in which we live is the age in which we are discovering the fundamental laws of Nature, and that day will never come again-RICHARD FEYNMAN (THE CHARACTER OF PHYSICAL LAW, 1965)

Compared to the wild flume ride of American high-energy physics, CERN has paddled steadily ahead like a steam-boat down the Rhone River. Each milestone has been part of a natural progression to machines of increasing might-able to push particle energies higher and higher. While American high-energy physics has become increasingly political-rising or falling in status during various administrations-the independence of CERN's directors.h.i.+p and its commitment, cooperation, and collaboration to carrying out projects already proposed have enabled it to successfully plot the laboratory's course for decades ahead.

One aspect of CERN's impressive efficiency is its ability to recycle older projects into key components of state-of-the-art devices. The old Proton Synchrotron, upon its retirement as a stand-alone machine, became an injector for the Super Proton Synchrotron (SPS). The SPS, in turn, has been used for a variety of purposes, including serving as a preaccelerator for more powerful devices. Little at CERN ever truly goes to waste, and this keeps costs relatively low.

This tendency to adapt obsolete projects for reuse as parts of new ones reflects the European need to conserve s.p.a.ce and vital resources. Europe is more crowded and doesn't have the luxury of unbridled development. Therefore a venture like the SSC involving building a completely new facility from scratch in a region far from other labs would be much less likely to happen.

By making use of the old seventeen-mile tunnel for the Large Electron-Positron Collider (LEP), the Large Hadron Collider (LHC) serves as the perfect example of accelerator recycling. Digging the LEP tunnel was a colossal undertaking. From 1983 to 1988, it represented the largest civil-engineering project in Europe. Because the main ring had to be wedged between the Geneva airport and the Jura mountains, engineers had little room to maneuver. Tunnel diggers were forced to blast through thick layers of solid rock. To account for changes in topography, the ring had to be tilted by one and a half degrees. Amazingly, the tunnel lined up nearly perfectly (when its ends were joined, they were less than half an inch off) and was precisely the right size. It is therefore fortunate that the LHC hasn't required a whole new tunnel but rather could be fit into the old one.

The decision to drop ultracool superconducting magnets into the LEP ring and turn it into a hadron collider-at the suggestion of Rubbia and others-was first discussed in the 1980s. (Hadrons, such as protons, are much more ma.s.sive than electrons and thereby require far stronger magnets, such as superconducting magnets, to be steered through the same ring.) Reportedly, practically from the time the LEP opened, Rubbia was anxious to have the tunnel converted. While the SSC was under construction, many CERN physicists hoped that the LHC could be finished first. A frequent rallying cry was to plan on opening the LHC two years before the SSC-thus beating the Americans to the good stuff. The SSC's cancellation added further impetus to the project, as it meant that the LHC would represent the main-or only-hope for finding certain ma.s.sive particles. The model of international compet.i.tion and vying labs confirming one another's results, which served well during an earlier era of smaller machines, would need to be replaced with international cooperation, centered in Europe.

The final decision to build the LHC came little more than a year after the SSC was canned. On December 16, 1994, CERN's nineteen member nations at the time voted to budget $15 billion over a two-decade span to build what would be the world's mightiest collider. Through its leaders' firm commitments, the continent that sp.a.w.ned Galileo and Kepler readied itself to be the vanguard of science once more.

Unlike with the SSC, politics played little discernable role in the LHC's construction. Each European country that belongs to CERN contributes a specific annual amount that depends on its gross national product. Richer countries, such as Germany, France, and the United Kingdom, sh.e.l.l out the bulk of CERN's budget-generally with no yearly debate over how much that amount will be. (The United Kingdom has recently become more cautious about future scientific projects, however.) Thus CERN administrators can rely on certain figures and plan accordingly.

Furthermore, unlike the American case, in Europe regional compet.i.tions have never decided where projects are built. The French communities of the Pays de Gex, the region where much of the tunnel is located, didn't launch a "Don't Mess with Gex" campaign to sway politicians one way or the other. Rather, they've quietly accepted CERN as a long-standing neighbor that shares the land with farmers, wine growers, cheese makers, and other producers. As the region's motto proclaims, Gex is "Un jardin ouvert sur le monde" "Un jardin ouvert sur le monde" (a garden open to the world). (a garden open to the world).

On the Swiss side, Geneva is used to all manner of international enterprises. The city where the League of Nations was established and famous treaties were signed now houses a plethora of global organizations-the U.N. European headquarters, the World Health Organization, the International Labour Organization, the International Federation of Red Cross and Red Crescent Societies, and many others. CERN is well accepted along with its kindred cooperative inst.i.tutions. The medley of researchers' foreign languages-including English, Russian, and field theory-is nothing special; Genevese diplomats can match that Babel and more.

Furthermore, over the centuries Geneva has seen its share of groundbreaking movements. Compared to the impact of the Reformation and the Enlightenment, slamming particles together underground barely registers on the city's Richter scale of history.

True, the French countryside west of Geneva is much quieter. To ensure a harmonious relations.h.i.+p, CERN has sought to minimize its impact on that region. The patchwork of pastures and vineyards that front the misty Jura mountains displays no visible indication that a giant particle-smas.h.i.+ng ring lies hundreds of feet beneath them. Only the occasional road signs steering CERN vans to scattered laboratory buildings, and the power lines scratching through the green and golden tapestry, offer clues as to what lies below.

The latter represents possibly the biggest source of contention-CERN is a huge drain on the region's electricity. Originally, this electricity was supplied by Switzerland; now it is furnished by France. When its machines are fully running, CERN expends about as much power as the entire canton of Geneva. Because of the predominance of electrical heating in the area, this usage would be felt mainly during wintertime. Consequently, as a considerate neighbor, CERN often adjusts its power needs to accommodate-for example, by scheduling shutdowns during the coldest time of year. Though this means less data collection, fortunately for the more athletic researchers, the winter closures are timed well with peak skiing season in the nearby Alps.

To prepare for the LHC project, the LEP tunnel needed to be completely gutted. After the final LEP runs took place in 2000, the refurbis.h.i.+ng could finally begin. Orders went out for thousands of superconducting magnets of several different types. One kind, called dipole magnets, were designed to steer twin proton (or ion) beams around the loop. (A subset of the LHC experiments will involve accelerating ions rather than protons.) Dipoles tend to guide charged objects in a direction perpendicular to their magnetic fields-ideal for maneuvering. A second variety of magnets, called quadrupoles, were targeted at focusing the beams, to prevent them from spreading too much. To simplify the LHC's design, these were placed at regular intervals. Other more complex magnet designs-called s.e.xtupoles, octupoles, and decupoles-were added to the mix to provide finer beam corrections. Like a delicate s.p.a.ce mission, the orbit needed to be tuned just right.

Because the particles rounding the LHC would be alternatively steered and focused, with ample room for experimentation, the machine was not planned to be a perfect circle. Rather, it was divided into eight sectors, each powered separately. Sectors consist of curved parts and straight intervals-the latter used for a variety of purposes including injecting particles, narrowing the beams, and conducting experiments.

Researchers realized that two extreme conditions would need to be maintained to make the LHC a success. These requirements would bring some of the most hostile aspects of outer s.p.a.ce down to Earth. First, the twin beam pipes, riding through the apertures of the magnets, would need to be kept as close to vacuum states as possible. That would allow the protons (and ions) to reach ultrahigh energies without bouncing off of gas molecules as in a pinball game. A pumping system was chosen that would maintain the pressure at 10-13 (one-tenth of one trillionth) that of the atmosphere at ground level. That's far from as empty as the interplanetary void, but it's closer to a pure vacuum than virtually anywhere else on Earth. (one-tenth of one trillionth) that of the atmosphere at ground level. That's far from as empty as the interplanetary void, but it's closer to a pure vacuum than virtually anywhere else on Earth.

Second, the thousands of magnets would need to be supercooled well below the critical temperatures that maintain their superconducting states. This would keep their magnetic fields as high as possible-more than 8.3 Tesla, double the field used at the Tevatron. To keep the temperatures so low would require superfluid helium-a highly correlated ultracool state of that element-at 1.9 degrees Kelvin (above absolute zero). That's even colder than the microwave background radiation detected by Penzias and Wilson in their confirmation of the Big Bang.

At first glance, it would seem to be prohibitively expensive to keep so many magnets so cold. Indeed, superfluid helium is very costly to produce. However, by surrounding each "cryomagnet" (as supercooled magnets are called) with an insulating vacuum layer, little heat from the outside would leak through. Emptiness is a great thermal blanket.

Another factor LHC designers had to reckon with has to do with lunar influences. Remarkably, the moon has a periodic lure on the region. No, there aren't full-moon-crazed werewolves haunting the woods near Ferney-Voltaire and Meyrin, eager to rummage through supercooled containers looking for frozen steaks-at least as far as we know. Rather, the moon's effect is purely gravitational. Just as it pulls on the oceans and creates the tides, the moon tugs on the ground, too. Rocks are certainly not as pliable as water, but they do have a degree of elasticity. Due to its lunar stretching, Earth's crust in Geneva's vicinity rises and falls almost ten inches each month. This creates a monthly fluctuation in the LHC's length of about 1/25 of an inch.1 The effect was first noted when the tunnel was used for the LEP and has been accommodated through corrective factors in any calculations involving ring circ.u.mference. The effect was first noted when the tunnel was used for the LEP and has been accommodated through corrective factors in any calculations involving ring circ.u.mference.

Topography played an even more important role when it came time to equip the LHC with detectors. Completely new caverns were excavated, with the largest, at "Point 1," to accommodate the most sizable detector, ATLAS (A Toroidal LHC ApparatuS). Three other detectors, called CMS (Compact Muon Solenoid), ALICE (A Large Ion Collider Experiment), and LHCb (Large Hadron Collider beauty) were placed at additional points around the ring. The designs for each of these detectors took many years of planning. Their approval recognized their complementary roles in the overall LHC mission-each contributing a unique means of measuring particular types of collision by-products and thereby primed for different kinds of discoveries.

The ATLAS project has been in the planning for more than a decade. It represents a fusion of several earlier projects involving researchers from a number of different countries. Experiences at earlier collider projects-those completed along with those aborted-played a strong role in shaping the detector's design.

Take, for instance, ATLAS's electromagnetic calorimetry (energy-gauging) system. It relies on a method William Willis proposed in 1972 for the ill-fated ISABELLE collider: using liquid argon to convert radiation into measurable electrical signals through the process of ionization. When ISABELLE was canceled, Willis included liquid argon calorimetry again in the proposal he developed with Barish and others for the GEM detector at the SSC. In addition to Brookhaven, where Willis was based, the technique came to be used at laboratories such as Fermilab and SLAC. Now Willis is the U.S. project manager for ATLAS, where his liquid argon method forms a key component of the detector's energy-measuring system.

If liquid argon is the blood flowing through the heart of ATLAS, silicon pixels and strips (wafers responsive to light, like digital cameras) offer the ultrasensitive eyes. Immediately surrounding its interaction point is a zone of maximum surveillance called the inner detector-where electronic eyes gaze virtually everywhere like a particle version of Big Brother. Except for the places where the beam line enters and leaves, the inner detector is completely surrounded by tiny light probes. In other words, it is hermetic, the ideal situation for high-energy physics where virtually all bases are covered. This state of maximum spy-camera coverage offers the optimal chance of reconstructing what happens in collisions.

To encapsulate the beam line in a symmetric way, most sections of ATLAS, the inner detector included, are arranged in a set of concentric cylinders, called the barrel, framed at the entrance and exit by disks perpendicular to the beam, called the end-caps. This geometry means that almost every solid angle from the beam line is recorded. The inner detector's tracking system includes photosensitive pixels and strips covering the three interior layers of the barrel as well as the end-caps.

Between the inner detector and the calorimeters is a solenoid (coil-shaped) superconducting magnet with a field of approximately 2 Tesla. Cryostats (systems for supercooling) keep the magnet at less than five degrees above absolute zero. The purpose of the solenoid magnet is to steer charged particles within the inner detector-bending them at angles that depend upon their momenta (ma.s.s times velocity). Therefore, the electronic tracking system, in tandem with the magnet, enables researchers to gauge the momenta of collision products.

After particles breach the boundary of the inner detector, they enter the realm of the electromagnetic calorimeter. Bas.h.i.+ng into lead layers, the electromagnetically interactive particles decay into showers and deposit their heat in the liquid argon bath, producing detectable signals. Delicate electronics pick up the signals from all of the energy lost, offering another major component of event reconstruction. Discerning the charge, momentum, and energy of a particle is like asking a soldier his name, rank, and serial number. Because each of these physical quant.i.ties is conserved, identifying each particle's information optimizes the chances of figuring out which unseen carriers (such as neutral particles) might be missing.

Only some of the featherweight particles, such as electrons, positrons, and photons, are knocked out completely in the electromagnetic calorimeter; heavier (and nonelectromagnetic) particles can slip through. These bash into a thick layer of steel tiles interspersed with scintillators-the hadron calorimeter. Sensors ab.u.t.ting that layer record the heat deposited by any particles subject to the strong force. There protons, neutrons, pions, and their hadronic cohorts make their final stands.

The only charged particles that can evade both types of calorimeters without being absorbed are muons. To ensnare them, the outermost, and largest, layers compose the muon system. It operates in some ways like the inner detector, with magnets and a tracking system, only on a far grander scale-dwarfing the rest of ATLAS. Pictures of ATLAS taken after its completion inevitably showcase the muon system's colossal end-cap: the Big Wheel.

The muon system's enormous superconducting magnets have a much different shape from the central magnet. Rather than a solenoid, they are toroidal (doughnut-shaped) but stretched out. At one-quarter the length of a football field, they are the largest superconducting magnets in the world. Eight of them carve through the outer barrel-like an eight-way apple slicer. The sheer size of these magnets magnifies the bending of muons as they pa.s.s through. Thousands of sensors track the muons' paths as they swerve-revealing those particles' precise momenta.

The particles that survive the full range of detection systems are those that are insensitive to both the electromagnetic and strong interactions. The prime suspects among these are neutrinos. Because they interact solely through the weak and gravitational forces, neutrinos are very hard to detect. ATLAS does not make an attempt to catch these; rather, components of their momenta and energy are estimated through a subtraction process. Because the protons, before colliding, are traveling along the beam line, their total transverse (at right angles to the beam direction) momentum must be zero. According to conservation principles, the total transverse momentum after the collision-determined by adding up the momenta of everything detected-ought to be zero as well. If it isn't, then subtracting that sum from zero yields the transverse momenta of unseen collision products. Therefore, the ATLAS researchers have a good idea of what the neutrinos have carried off.

A view of the ATLAS detector with its eight prominent toroidal magnets.

Halfway around the LHC ring, beneath the village of Cessy, France, is the other general-purpose detector, CMS. The "compact" in its name reflects the CMS's aspiration to pursue similar physics to ATLAS with a detector a fraction of the volume-although still bigger than a house. Instead of an a.s.sortment of magnets, CMS is constructed around a single colossal superconducting solenoid (coil-shaped magnet) that puts out a field of 4 Tesla-approximately a hundred thousand times greater than the Earth's. It surrounds the detector's central silicon-pixel tracker and calorimeters, bending the routes of charged particles within those regions and extracting precise values of their momenta. Knowing the momenta helps the researchers reconstruct the events and deduce what might be missing, such as neutrinos.

Another difference between CMS and ATLAS concerns the way they force electromagnetically sensitive particles to "take a shower." Instead of frigid liquid argon, the CMS electromagnetic calorimeter includes almost eighty thousand lead tungstate crystals (energy-sensitive materials) to measure the energies of electrons, positrons, and photons in particle showers. The hadrons encounter dense curtains of bra.s.s and steel, while muons are caught up in layers of drift chambers and iron that lie just beyond the magnet.

The CMS detector before closure.

The two collaborations have much in common: large teams of researchers from inst.i.tutions around the world, ambitious goals, and the powerful data-capturing technologies required to carry out these bold objectives. Data from the millions of events recorded by each group-those pa.s.sing the muster of the trigger systems designed to weed out clearly insignificant occurrences-will be sent electronically to thousands of computers in hundreds of centers around the world for a.n.a.lysis by means of a state-of-the-art system called the Grid.

Each team has an excellent shot at identifying the Higgs boson, a.s.suming its energy falls within the LHC's reach. If one team finds it, the other's efforts would serve as vital confirmation. The research paper making the important announcement would literally contain thousands of names. Because of the shared credit, the n.o.bel committee would be hard-pressed to award its prize to an individual or small set of experimentalists. Unlike, for instance, Rubbia and Van der Meer's winning science's highest honor for the weak boson discoveries, there probably wouldn't be obvious hands (aside from those of its namesake theorist) to confer the award.

Completing the quartet at the LHC's interaction points are two sizable specialized detectors: the LHCb (Large Hadron Collider beauty) experiment and ALICE (A Large Ion Collider Experiment). Two other pet.i.te detectors will operate near the ATLAS and CMS caverns, respectively: the LHCf (Large Hadron Collider forward) and TOTEM (TOTal Elastic and diffractive cross-section Measurement) experiments.

The focus of the LHCb experiment is to produce B-particles (particles containing the bottom quark) and to examine their modes of decay. B-particles are extremely ma.s.sive and would likely have a rich variety of decay products that could possibly furnish evidence of new phenomena beyond the Standard Model. In particular, the LHCb researchers will be looking for evidence of what is called CP (Charge-Parity) violation. CP violation is a subtle discrepancy in certain weak interactions when two reversals are performed in tandem: switching the charge (from plus to minus or minus to plus) and flipping the parity (taking the mirror image). Switching the charge of a particle makes it an antiparticle, which does not always behave the same in weak decays. Reversing the parity, as Lee and Yang demonstrated, similarly does not always yield the same results in weak decays. Physicists once believed that the combination of the two operations would always be conserved. However, in 1964, American physicists James Cronin and Val Fitch demonstrated that certain kaon processes subtly break this symmetry. Particular B-meson decays involving the weak interaction also violate CP symmetry-processes that the LHCb experiment hopes to study.

Unlike ATLAS and CMS, the LHCb detector does not surround its whole interaction point. Instead, it consists of a row of subdetectors in the forward direction. The reason is that the B-particle decays to be studied generally fan out in a cone in front of the collision site. Several hundred researchers from more than a dozen countries are members of the LHCb collaboration.

ALICE is an experiment that involves the collision of lead ions rather than protons. The LHC will circulate ions for one month each year to accommodate this project. When the lead ions collide, the hope is that they will produce a state of matter called quark-gluon plasma-a free-flowing mixture of hadron const.i.tuents thought to resemble the primordial broth that filled the very early universe. Normally, quarks are confined to hadrons-grouped in pairs or triplets and strung together by gluons. However, under the energetic conditions of the LHC, equivalent to more than a hundred thousand times the temperature at the Sun's core, physicists think such barriers would crumble-liberating the quarks and gluons. This freedom would be extraordinarily brief. The ma.s.sive detector used to record the outcome has a layered barrel design with eighteen components, including various types of tracking systems and calorimetry. More than a thousand physicists from more than a hundred different inst.i.tutions are contributing to the project.

The LHCf experiment, the smallest at the LHC, makes good use of some of the leftovers from ATLAS. Standing in the beam tunnel about 460 feet in front of the ATLAS collision point, it is intended to measure the properties of forward-moving particles produced when protons crash together. The goal is to test the capability of cosmic ray measuring devices. Several dozen researchers from six different countries are involved in the experiment.

Finally, TOTEM, a long, thin detector connected to the LHC beam pipe, is geared toward ultrahigh-precision measurements of the cross-sections (effective sizes) of protons. Located about 650 feet away from the CMS detector, it consists of silicon strips situated in eight special vacuum chambers called Roman pots. These are designed to track the scattering profiles of protons close to the beam line. TOTEM involves the work of more than eighty researchers, a.s.sociated with eleven inst.i.tutions in eight different nations.

To monitor the progress of the LHC experiments, members of each group conduct regular meetings. Particularly for the larger detectors, each instrumental component requires calibration and careful monitoring. Group members frequently apprise one another of the results of this testing to troubleshoot any potential problems.

One issue that sometimes arises with the more complex detectors is antic.i.p.ating how one component might affect another's results-for example, through electronic noise. The presence of ultrastrong magnetic fields further complicates matters, as they could exert disruptive influences. During testing at ATLAS in November 2007, for example, one of the toroid magnets wasn't properly secured and it moved about an inch toward an end-cap calorimeter. Fortunately, there was no damage. If a problem is found within one of the hermetically sealed sections, often nothing can be done until it is unsealed and opened up. Typically, such opportunities arise when the LHC is temporarily shut down-close to the winter holidays, for example.

The "machine people," those involved with the planning and operations of the accelerators, have their own separate meetings. Their primary concern is that the overall system is working smoothly. One of the trickiest issues they face is keeping the dipoles, quadrupoles, and other ring magnets at their optimal fields with maximum energies.

If the magnetic fields and energies are raised too high in too rapid a manner, an adverse phenomenon called quenching occurs. Quenching is when part of a superconducting magnet overheats because of moving interior components and destroys the superconductivity. At that point, the magnet becomes normally conducting and its field drops to unacceptable levels. To combat such a ruinous situation, the magnetic fields are ramped up slowly, then reduced, again and again, in a process called training. It's a bit like placing your feet in a hot tub, pulling them out, then putting them back in again, until you are used to the heat.

The detector and the machine groups are well aware of the LHC's limitations. Every machine has structural limits-for example, upper bounds on the beam luminosity due to the magnets' maximum focusing power. Consequently, researchers take note and plan for upgrades well in advance. It is remarkable that while some team members of the various collaborations are readying current experiments, others are involved in developing scenarios for modifying aspects of the detectors and accelerators years in advance. A planned luminosity upgrade to turn the LHC into the "Super LHC" is already intensely under discussion. Modern particle physics requires envisioning situations today, tomorrow, and decades ahead-sometimes all wrapped together in the same group meetings.

Amid all of these preparations, researchers try to keep their eyes on the big picture. Results could take years, but the history of science spans the course of millennia. The identification of the Higgs boson and/or the discovery of supersymmetric companion particles could shape the direction of theoretical physics for many decades to come. Another field eagerly awaiting the LHC findings is astronomy. Astronomers hope that new results in particle physics will help them unravel the field's greatest mystery: the composition of dark matter and dark energy, two types of substances that affect luminous material but display no hint of their origin and nature.

9.

Denizens of the Dark Resolving the Mysteries of Dark Matter and Dark Energy

I know I speak for a generation of people who have been looking for dark-matter particles since they were grad students. I doubt . . . many of us will remain in the field if the L.H.C. brings home bad news.-JUAN COLLAR, KAVLI INSt.i.tUTE FOR COSMOLOGICAL PHYSICS (NEW YORK TIMES, MARCH 11, 2007) There's an urgency for LHC results that transcends the ruminations of theorists. For the past few decades, astronomy has had a major problem. In tallying the ma.s.s and energy of all things in the cosmos, virtually everything that gravitates is invisible. Luminous matter, according to current estimates, comprises only 4 percent of the universe's contents. That small fraction includes everything made out of atoms, from gaseous hydrogen to the iron cores of planets like Earth. Approximately 23 percent is composed of dark matter: substances that give off no discernable light and greet us only through gravity. Finally, an estimated 73 percent is made of dark energy: an unknown essence that has caused the Hubble expansion of the universe to speed up. In short, the universe is a puzzle for which practically all of the pieces are missing. Could the LHC help track these pieces down?

Antic.i.p.ation of the missing matter dilemma dates back to long before the issue gained wide acceptance. The first inkling that visible material couldn't be the only hand pulling on the reins of the universe came in 1932, when Dutch astronomer Jan Oort found that stars in the outer reaches of our galaxy moved in a way consistent with much greater gravitational attraction than observed matter could exert. The Milky Way is in some ways like a colossal merry-go-round. Stars revolve around the galactic center and bob up and down relative to the galactic disk. Oort found that he could measure these motions and calculate how much total gravitational force the Milky Way would need to exert to tug stars back toward its disk and prevent them from escaping. From this required force, he estimated the Milky Way's total ma.s.s, which became known as the Oort Limit. He was surprised to find that it was more than double the observed ma.s.s due to s.h.i.+ning stars.