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After more than fifteen years of planning and more than eight billion dollars in funding, the Large Hadron Collider (LHC), science's groundbreaking effort to unlock the deepest secrets of particle physics, is finally complete. It is truly the grandest experiment of all time — the pinnacle of humanity's quest for unification. Befitting the pursuit of cosmic grandeur and unity, it is set in a stunning location.
The new book by physicist Paul Halpern is available online and in bookstores. Hear more about super colliders from the author in a Q&A with Wired.com.
Query a world traveler about locales of striking beauty and harmony, and chances are Switzerland would be high up on the list. From its majestic mountains and crystalline lakes to its quaint cog railways and charming medieval towns, it is hard to imagine a better place to base a search for unification. Indeed the Swiss confederation, uniting inhabitants divided into four different official languages (French, German, Italian, and Romansch), several major religions (Protestant, Catholic, and other faiths), and twenty-six distinct cantons, physically isolated in many cases from one another, represents a model for bringing disparate forces together into a single system. Though in past centuries Switzerland experienced its share of turmoil, in more recent times it has become a haven for peace and neutrality.
As Europe's political frontiers have receded, many scientific roadblocks have fallen as well. The LHC crosses the Swiss-French border with the ease of a diplomat. Its seventeen-mile-long circular underground tunnel, recycled from a retired accelerator called the Large Electron-Positron Collider (LEP), represents a triumph for international cooperation. Only by working in unison, it reminds us, might we discover the secrets of natural unity.
American researchers form a large contingent in the major LHC experiments. They are proud to contribute to such a pivotal venture. Although the United States is not a member of CERN, it donates ample funds toward LHC research. While celebrating Europe's achievements, however, many American physicists still quietly mourn what could have taken place at home.
In 1993, the U.S. Congress voted to cut off funding for what would have been a far bigger, more powerful project, the Superconducting Super Collider (SSC). About fourteen miles of a planned fifty-four-mile tunnel in the region of Waxahachie, Texas, had already been excavated before the plug was pulled. Today that land sits fallow, except for the weed-strewn abandoned buildings on the site. Years of anticipation of novel discoveries were crushed in a single budgetary decision.
President Bill Clinton sent a letter to the House Appropriations Committee expressing his strong concerns: "Abandoning the SSC at this point would signal that the United States is compromising its position of leadership in basic science — a position unquestioned for generations."
Nevertheless, tight purse strings won out over sweeping visions. The cancellation of the SSC shattered the plans of those who had made multiyear commitments to the enterprise and discouraged young researchers from pursuing the field. It would prove a horrendous setback for American high-energy physics, shifting the momentum across the Atlantic.
By delivering a planned 20-TeV burst of energy with each collision, the particle-smasher in Texas would have been energetic enough to conduct a thorough search for the elusive God particle. Perhaps in its hatchery, supersymmetric companion particles would have been born, presenting themselves through their characteristic decay profiles. Dark matter could have made itself known in caverns deep beneath the Texas soil. The ramifications of string theory and other unification models could have been explored. Like the moon landings, these expeditions could have been launched from U.S. soil. With the LHC's completion, the Tevatron will soon be obsolete and no more large American accelerators are planned. What went wrong?
The reason lies with long-term planning and commitment to science, an area where sadly the United States has in recent times often fallen short. Each European member of CERN pledges a certain amount every year, depending on its gross national product. Thus the designers of the LHC could count on designated funding over the many years required to get the enterprise up and running. Already, the upgrades of coming years are being programmed. Foresight and persistence are the keys to the LHC's success.
Not that there haven't been frustrating glitches and delays. Contemporary high-energy physics requires delicate instrumentation that must be aligned perfectly and maintained in extreme environmental conditions such as ultracold temperatures. Despite researchers best efforts, systems often fail. Originally supposed to go on line in 2005, the LHC wasn't yet ready. Its opening was delayed again in 2007 because of accidental damage to some of its magnets.
On September 10, 2008, proton beams were circulated successfully for the first time around the LHC's large ring. Project leader Lyn Evans and the international team of researchers working at the lab were elated. "It's a fantastic moment," said Evans. "We can now look forward to a new era of understanding about the origins and evolution of the universe."
Nine days later, however, that heady summer of hope screeched to a halt due to a devastating malfunction. Before particle collisions had even been attempted, a faulty electrical connection in the wiring between two magnets heated up, causing the supercooled helium surrounding them to vaporize. Liquid helium is a critical part of the LHC's cooling system that keeps its superconducting magnets functioning properly. In gaseous form, the helium began to leak profusely into the vacuum layer that surrounds the system, thwarting attempts by emergency release valves to channel it off safely. Then came the knockout punch. The flood of helium slammed into the magnets, jostled them out of position, and destroyed more wiring and part of the beam pipe. Upon inspection, technicians realized that it would take many months to repair the damage, recheck the electrical and magnetic systems around the ring, and attempt operations once more. Currently, the LHC is scheduled to go on line in September 2009.
When it is up and running, the LHC will be a marvel to behold — albeit remotely, given that its action will take place well beneath the surface. Burrowed hundreds of feet beneath the earth but only ten feet in diameter, the LHC tunnel will serve as the racetrack for two opposing beams of particles. Steered by more than a thousand gigantic supercooled magnets — the coldest objects on Earth — these particles will race eleven thousand times per second around the loop, traveling up to 99.999999 percent of the speed of light. Reaching energies up to 7 TeV each, the beams will be forced to collide at one of four designated intersection points.
One of these collision sites houses the ATLAS (A Toroidal LHC ApparatuS), detector, a colossal instrument seven stories high (more than half the height of the Statue of Liberty) and spanning 150 feet (half the length of a football field) from end to end. Using sensitive tracking and calorimetry (energy-measuring) devices, it will monitor the debris of protons crashing together in its center, collecting an encyclopedia of data about the by-products of each collision. Halfway around the ring, another general-purpose detector called CMS (Compact Muon Solenoid) will employ alternative tracking and calorimetry systems to similarly collect reams of valuable collision data. At a third site, a specialty detector called LHCb (Large Hadron Collider beauty) will search for the decays of particles containing bottom quarks, with the hope of discovering the reason for the dearth of antimatter in the cosmos. Finally, at a fourth collision site, another specialized detector called ALICE (A Large Ion Collider Experiment) will be reserved for times of the year when lead ions are collided instead of protons. By smashing these together, researchers hope to re-create some of the conditions of the early universe. From each detector, based on careful assessment of the signals for possible new particles, the most promising information will be sent off for analysis via a global computing network called the Grid.
A vast group of researchers from numerous countries around the world will wait eagerly for the LHC results, hoping to find signs of the Higgs, supersymmetric companions, and other long-hoped-for particles. Discovery of any of these would spur a renaissance in physics and an enormous boost for the scientific enterprise — not to mention grounds for a Nobel Prize. The world would celebrate the achievements of those involved in this extraordinary undertaking, including the hardworking Evans and the thousands of workers contributing their vital efforts and ideas to the project.
Images: CERN
See Also:
- Last Days of Big American Physics: One More Triumph, or Just Another Heartbreak
- The Large Hadron Collider Demystified
- For Sale: $20 Million Particle Accelerator, Never Used
- Large Hadron Collider: Best- and Worst-Case Scenarios
- Large Hadron Collider Down Until 2009
- Next-Gen Atom Smashers: Smaller, Cheaper and Super Powerful
