Image: ALICE collision
In this graphic visualization, particle tracks fly out from the heart of the Large Hadron Collider's ALICE detector from one of the first collisions at total energy of 7 trillion electron volts. staff and news service reports
updated 7/26/2010 1:23:52 PM ET 2010-07-26T17:23:52

Scientists behind the European particle collider aimed at uncovering the secrets of the universe pushed Monday to build an even bigger machine — with money and partners from around the world.

Instead of whirling atoms in giant rings, as existing colliders in Switzerland and the United States do, scientists want a new-generation machine that will shoot them straight.

Particle physicists gathering in Paris on Monday for the most important conference in their field say a linear atom blaster is needed to complement what existing colliders are telling scientists about the universe, inching them closer to understanding why we are here.

Mel Shochet, a professor at the University of Chicago, said "this is by far the most exciting time" in his particle physics career.

Speaking at a Paris news conference, Shochet said "exciting new phenomena" would be seen first by existing colliders "and then followed up in great detail" by future machines, he said at a Paris press conference.

Depending on who wants to host it — and how much they are willing to pay — the next-generation collider could potentially be built anywhere in the world — with Japan, Russia, the U.S. and Switzerland all possible hosts for the most advanced project.

‘Pretty happy’ with LHC results
Scientists are fortified by the results of the $10 billion Large Hadron Collider run by CERN, a particle physics laboratory outside Geneva. A smaller collider called Tevatron is run by Fermilab near Chicago. Both are highly complex machines that took years to bring to fruition.

Rolf Heuer, head of CERN, said he is "pretty happy" about what scientists have so far discovered in Switzerland.

"This is a dark universe" into which the machine "will shed the first light," he said.

It will be the "interplay and combination of results" between the two different types of atom smashers that allows high-energy physics to advance, he said.

More than 1,000 physicists have gathered in Paris to hear the latest findings from the colliders — and the preparations for their successors — at the International Conference on High Energy Physics, or ICHEP, which runs through Wednesday.

The experiments are more about shaping our understanding of how the universe was created than immediate improvements to technology in our daily lives. Scientists are attempting to simulate the moments after the big bang nearly 14 billion years ago, which they theorize was the creation of the universe.

So far, research at the LHC has focused on retracing past discoveries, so that scientists can feel as if they're on sure footing as they push ahead into the frontiers of physics. Physicists at ICHEP reported the first European detection of the top quark — a massive, short-lived particle previously identified only in the United States.

"From now on, we are in new territory," said Oliver Buchmueller, a senior CERN researcher. "What we are doing is effectively going back in time. The higher we raise the energy, the closer we come to what was happening at the big bang."

The next steps
Plans for the next step include a $12.85 billion (€10 billion), 31-mile (50-kilometer) tunnel called the International Linear Collider; and the Compact Linear Collider, or CLIC, which is as yet uncosted.

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"Both are now really international cooperations, collaborations," said Heuer.

He said plans for the ILC, which first originated in a Hamburg laboratory, are more technologically advanced, but the rival collider aims at higher-energy experiments. The choice will be determined by the discoveries at CERN, or the European Organization for Nuclear Research, he said.

Barry Barish, director of the proposed ILC, told The Associated Press that scientists could have the technology ready to go ahead with his project in 2012.

"If we are going to build an ambitious machine, then it's got to be a global machine," said Barish, a professor at the California Institute of Technology.

The rival project could be five to 10 times more powerful than the ILC — depending on how much funding is available, according to Jean-Pierre Delahaye, CLIC study leader at CERN, who is involved in both projects. "When we go up in energy, we get closer to the Big Bang moment," he told the AP.

French President Nicolas Sarkozy, speaking at the conference on Monday, vowed to keep investing in science despite the need to reduce public spending. But investments of the scale being discussed in Paris "can't be made by a single country, not even by a small group of countries," he said.

After problems, smooth sailing
The collider under the Swiss-French border was launched with great fanfare in September 2008, but days later was sidetracked by overheating that set off a chain of problems. CERN had to undertake a $40 million program of repairs and improvements before restarting the machine in November. Since then the collider has reported a series of successes.

In March, the Large Hadron Collider produced its first bang, the most potent force on the tiny atomic level that humans have ever created.

Two beams of protons were sent hurtling in opposite directions toward each other in a 17-mile (27-kilometer) tunnel below the Swiss-French border — the coldest place in the universe at slightly above absolute zero.

CERN used powerful superconducting magnets to force the two beams to cross; two of the protons collided, producing 7 trillion electron volts.

Instead of crashing protons together, the planned new colliders will accelerate electrons and positrons, their antimatter equivalent, said Guy Wormser, a leading particle physicist and one of the conference organizers.

Heuer said that CERN's experiments so far have "done an incredible job," locating the particles scientists already knew existed. Now their job is to find new ones.

Progress on search for 'God particle'
Scientists are searching for the Higgs boson, a hypothetical particle — often called the God particle — that scientists theorize gives mass to other particles and thus to other objects and creatures in the universe. The colliders also may help scientists see dark matter, the strange stuff that makes up more of the universe than normal matter but has not been seen on Earth.

Researchers at Fermilab haven't found the Higgs, but they have narrowed the range of masses in which the particle could exist, said the University of Chicago's Shochet.

Collaborators from two of the teams using Fermilab's Tevatron, CDF and DZero, announced combined results that ruled out the range of masses between 158 and 175 GeV/c2. Previous experiments have excluded Higgs particle masses below 114 GeV/c2 and above 185 GeV/c2. In comparison, the proton's mass is just less than 1 GeV/c2.

Before the ICHEP conference, some physicists speculated that the Tevatron teams would report the first evidence of the Higgs' existence. Monday's announcement fell short of that achievement, but scientists believe it's just a matter of time before the Tevatron or the LHC makes such a discovery. Not finding the Higgs would be an even more provocative development, because it would force researchers to revise the Standard Model of particle physics, one of history's most successful scientific theories.

Eventually, such discoveries could lead to new energy and communication technologies, just as past breakthroughs in particle physics have led to nuclear power, lasers and cell phones. But during Monday's speech at ICHEP, Sarkozy instead emphasized the bigger picture.

"Your work represents the oldest dream of man since he tried to understand and transform what goes on around him," Sarkozy said. "Why is there something rather than nothing?"

This report includes information from The Associated Press, Reuters and

© 2013

Interactive: Inside the big bang machine

Explainer: What’s a hadron? Tour the particle zoo

  • Image: Elementary particles

    The Standard Model of particle physics is one of science's most successful theories, enabling the development of devices ranging from light bulbs, to microwave ovens and television, to quantum computing devices. The Standard Model is also one of the oddest theories, because it lays out a dizzying menagerie of hundreds of subatomic particles. At its heart are 16 types of elementary particles ... plus at least one more mysterious particle that scientists are spending billions of dollars to detect.

    Click on "Next" to get the full rundown.

  • Quarks

    Image: Quarks and gluons
    Berkeley Lab

    Six "flavors" of quarks have been detected: up and down, charm and strange, top and bottom. Quarks are almost always found in different combinations, bound together by gluons (more on those later). Particles built up from quarks and gluons are called hadrons. The Large Hadron Collider is so named because it's a large collider that smashes hadrons together.

    Three-quark combinations fit in the category of baryons. The best-known baryons are the proton (with two up quarks and one down quark) and the neutron (with two down quarks and one up quark).

    Particles that have one quark and one antiquark fit in the category of mesons. For example, the pion, or pi meson, contains an up quark and an anti-down quark.

  • Leptons

    Image: Single electrons in helium
    Brown University

    Six "flavors" of leptons have been detected: The negatively charged electron is the best-known lepton — along with its antimatter counterpart, the positron. This photo shows the path of single electrons passing through liquid helium, in an experiment devised by Brown University researchers.

    The muon is also negatively charged, but it's about 207 times as massive as the electron. ("Who ordered that?" physicist Isidor Rabi reportedly asked.) The negatively charged tau particle is even bigger — 3,477 times as massive as the electron — but it decays into other particles in less than a trillionth of a second.

    Each of those leptons has a neutrino associated with it: the electron neutrino, the muon neutrino and the tau neutrino. Neutrinos interact only weakly with other particles, and they zip through our planet virtually without a trace. Physicists only recently determined that they have mass, but there's still a great deal of mystery surrounding the ghostly particles.

  • Force carriers

    Image: Graviton

    The Standard Model sets aside a category for particles that are associated with force fields. The effect of a field can be viewed as involving an exchange of such force-carrying particles.

    Four elementary force-carrying particles have been detected. The best-known force carrier is the photon — which plays a part in the electromagnetic spectrum, including visible light. The gluon binds quarks together through the strong nuclear force. The weak nuclear force involves the exchange of W and Z bosons. The W boson can carry a positive or a negative charge, while the Z boson is neutral.

    If gravity could be incorporated into the Standard Model, the force-carrying particle would be called the graviton (shown here in an artist's depiction). However, gravitons have not yet been detected, and at least for now, such particles are not accounted for in the Standard Model.

  • Bosons vs. fermions

    Image: Bosons vs. fermions
    Rice Univ. via AIP

    All force-carrying particles are bosons, but not all bosons are force carriers. The difference has to do with a property known as particle spin. Particles with a fractional spin value (for example, electrons, protons and neutrons) are fermions. Two identical fermions cannot occupy the same quantum state. This is a property that keeps electrons from collapsing into a jumble, and thus makes chemical reactions possible.

    All particles with a whole-integer spin value are classified as bosons, and such particles can occupy the same quantum state even if they're identical. The photon is the best-known type of boson.

    Even atoms can be classified as fermions and bosons. This photo shows how atom clouds of lithium-7 (bosons) and lithium-6 (fermions) behave at low temperatures. The bosons collapse into a compact cloud, while the fermions can't squeeze that closely together.

  • The mysterious Higgs

    Image: Higgs as seen by CMS
    Ianna Osborne / CERN / CMS Collection

    The Higgs boson is the only particle predicted by the Standard Model that has not yet been detected. The Higgs is the main quarry for physicists at the Large Hadron Collider. This image is a simulation of the Higgs' signature as it might appear in one of the LHC's detectors.

    The Higgs boson, named after Scottish theorist Peter Higgs, is thought to be associated with a field that endows some particles (such as the weak nuclear force's W and Z bosons) with mass, while leaving the electromagnetic force's photons without mass.

    This Higgs field may have played a role at the very beginnings of the universe: Physicists believe that at the highest energies, the electromagnetic and weak nuclear forces were unified, but something led to "electroweak symmetry breaking" as the infant cosmos cooled. That would be why the electromagnetic force and the weak nuclear force are distinct in the current universe. The Large Hadron Collider could shed new light on this mysterious Higgs mechanism.

  • Why so complicated?

    Image: Particle zoo
    Tim Jones / McDonald Observatory / HETDEX

    Hadrons and leptons? Baryons and mesons? Fermions and bosons? Sometimes it seems as if particle physicists set up these classifications just to keep outsiders totally confused. But for researchers, these occasionally overlapping categories are useful for figuring out how different types of particles interact with each other.

    In a sense, it's as if we've been talking about the game of chess but have gotten only to the point of naming the different pieces on the board: black pieces and white ones, pawns and knights, bishops and rooks, kings and queens. The real meaning of the game comes out when you start studying how the pieces perform and interact.

    To delve into the deeper meaning of the Standard Model, you can visit The Particle Adventure at Lawrence Berkeley National Laboratory, "A Subatomic Venture" at CERN, or Particle Physics UK.


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