Thursday, April 15, 2010

First high-energy collisions carried out in Geneva

Wild whooping and cheering broke out as scientists celebrated the “dawn of a new era” of physics yesterday with the first high-energy collisions at the Large Hadron Collider.
In the moments after the images of collisions were beamed into each of the four LHC control rooms, physicists of all ages and nationalities hugged each other, jumped up and down and popped champagne corks.

Heidi Sandaker, a Norwegian physicist, had even brought her baby into work so that her child was “there” at the moment the collisions took place.

After a year’s setback and, for some, several decades of hard work, the beams of protons first smashed together just after noon BST. It was five hours behind schedule but well within the time frame expected by scientists at the European Centre for Nuclear Research (CERN). Two failed attempts in the morning, starting at 5am BST, were enough to ramp up tensions.

On the third attempt scientists watching the event live from around the world described it as an “historic moment” marking the first step towards addressing some of the deepest mysteries in physics. “We are going where nobody has been before. We have opened a new territory for physics,” said Oliver Buchmueller, a senior CERN scientist.

The atomic particles smashed together in head-on collisions, with each beam having an energy of 3.5 trillion electron volts, three times the previous record. By creating ultra-high energy collisions, scientists are mimicking the conditions just after the Big Bang. The two proton beams began circulating ten days ago in opposite directions around a 17-mile (27km) tunnel under the Swiss-French border at Geneva.

Scientists hope that the LHC will eventually find evidence for the existence of the Higgs boson, a particle that theoretically explains the origin of mass but which has never been detected. The LHC will also investigate dark matter, extra-spatial dimensions and whether fundamental particles, such as quarks and leptons, can be broken down into even tinier components.

“We could be on the verge of a revolution of the type we saw in physics 100 years ago,” said Jürgen Schukraft, spokesman for the Alice experiment, one of the tests taking place. “The LHC seems to have the key to the answers for a lot of things that don’t add up.”

Professor Rolf Heuer, the director-general of CERN, and his deputy, Sergio Bertolucci, were not present for the collisions due to an engagement with the Japanese science minister. Speaking via video-link from the University of Tokyo, with a bottle of wine beside him and glass in hand, Professor Heuer said: “This bottle is from 1991, the year we got sign-off for the LHC. The bottle is empty, but the physics channels will be full very soon. Santé. Stay tuned.”

The announcement of successful collisions brought an outpouring of relief and excitement from scientists who have guided the project. Many had been working continuously through Monday night and Tuesday morning to ensure everything ran smoothly.

Professor Christophe Delaere, a physicist from the University of Louvain, Belgium, had been working for more than 24 hours. “It’s a really exciting moment,” he said.

“I don’t have a speech prepared, because all I’ve been thinking about is Atlas,” said Fabiola Gianotti, leader of the Atlas project, after the collisions. “It’s so intense, everyone’s feeling a big emotion, a big enthusiasm. It’s a machine of unprecedented size and complexity, but behind that are the people, and particularly the young scientists.”

Betting has already begun on what will be the first discovery at the LHC, with the Irish bookmaker PaddyPower making dark matter the 11-10 favourite, followed by black holes at 8-1 and dark energy at 12-1. God remains the 100-1 outsider.

Questions the LHC hopes to answer :

Dark matter

The existence of an “exotic” type of matter that cannot be seen but whose gravitational effects can be felt, was first hypothesised in 1934 to account for evidence of “missing mass” in galaxies. Dark matter is believed to make up about three quarters of all matter in the Universe, but only the most tantalising hints of it have ever been detected experimentally.

Higgs boson

The celebrity particle of the LHC, which could explain the origin of mass, was first proposed theoretically in 1964 by Peter Higgs, but has never been observed.

Supersymmetry

The idea that every particle in the Universe has a symmetric, heavier twin. This idea is an elegant theory, but there is very little evidence for it.

Recreating the big bang

The Alice experiment will collide heavy lead nuclei, generating temperatures 100,000 times those at the centre of the Sun and producing a tiny sample of the “primordial soup” that existed just after the Big Bang.

Extra dimensions

In daily life we experience three spatial dimensions, but physicists think there could be either ten or twenty-six curled up so tightly that they are invisible to us

The LHC substructure of fundamental particles

The LHC is the highest energy particle accelerator, meaning it could find quarks in particles.

http://www.timesonline.co.uk/tol/news/science/physics/article7081212.ece

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