Thursday, September 18, 2008

Large Hadron Collider: First subatomic particle collision to happen next week

By Roger Highfield, Science Editor

The first collisions between subatomic particles will take place in the Large Hadron Collider next week, which will mark another milestone for the biggest experiment in history.

"If we get stable conditions, I am very optimistic things will go quite fast," says Dr Lyn Evans, the coal miner's son from Aberdare, South Wales, who is leader of the £4.4 billion particle accelerator, a project that involves around 10,000 scientists and engineers worldwide.

One of the first images taken with CMS, one of the detectors, after a beam of particles was smashed into a tungsten block
One of the first images taken with CMS, one of the detectors, after a beam of particles was smashed into a tungsten block

The LHC circulates particles in a 17 mile circumference underground tunnel straddling the French-Swiss border at The European Organization for Nuclear Research, near Geneva, Switzerland, known by the acronym Cern.

Although there was much ballyhoo last week about the first particles - protons - to whirl around the LHC at a shade under the speed of light, the real aim of the exercise is to bring counter rotating beams of particles into collision in the four "eyes" - detectors - of the machine to recreate conditions not seen since just after the birth of the universe.

This is the aspect of the experiment that has triggered all the angst and hand-wringing by doomsayers and Jeremiahs who fear that the collisions will mark the end of the world, as it tumbles into the gaping maw of a black hole.

These fears have been dismissed as nonsense by Dr Evans, along with scientists such as Prof Stephen Hawking, who say that the end of the world is not nigh.

The original plan was to take 31 days from the first proton beams circulating in the LHC to smashing protons for the first time.

"We were going along at a real good lick," Dr Evans said of the days after particles first circulated.

But the cryogenics that keep the great machine cool - it is the biggest fridge on the planet - went down on Friday, as a result of thunderstorms disrupting the power supply.

"We have had problems with the electricity supply for various reasons and the cryogenics is recovering from that, so we will not have a beam again, probably until Thursday morning," says Dr Evans.

The team now hopes to achieve collisions at between one fifth and one tenth of the full energy in a few days.

"We are very confident that we can go quite quickly. The experiments have asked us for some early collisions, at low energy. If we get stable conditions, we will get there next week."

The collisions will take place in the two general purpose detectors of the giant machine, called Atlas and CMS, though Dr Evans adds the team will also attempt collisions in Alice, which will study a "liquid" form of matter, called a quark-gluon plasma, that formed shortly after the Big Bang, and an experiment called LHCb, which will investigate the fate of antimatter in the wake of the Big Bang.

Dr Lyn Evans in the control room of the Large Hadron Collider
Dr Lyn Evans in the control room of the Large Hadron Collider

"The main objective is to get to 5TeV" (that target energy per beam is equivalent to 10Tev collisions, while the LHC is designed to reach 14 TeV working full steam), said Dr Evans.

He says "I don't know how long that will take," though the schedule predicts that 14 TeV will be reached next year.

"We would not go to very high energy next, week, we are not that clever," said "Evans the Atom".

The LHC will be able to create fundamental particles that are too heavy to have been produced using existing particle colliders.

One of these could be the Higgs boson, named after the Edinburgh based physicist, which the LHC was built to find using the Atlas and the CMS detectors.

If discovered, the Higgs - jokingly called the "god particle" - would complete the Standard Model of particle physics by explaining how particles get their different masses.

The great machine may also catch a glimpse of a "supersymmetric" world, where a new myriad of heavy particles mirror those of the Standard Model, which may be responsible for a mysterious gravity source, called dark matter.

Although based on much more speculative theories, the LHC may even find exotic entities such as mini black holes or evidence for additional dimensions.

Original here

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