080922 Large Hadron Collider powered down in first week

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Large Hadron Collider powered down in first week
BY DR EMILY BALDWIN
ASTRONOMY NOW

Posted: September 22, 2008

The Large Hadron Collider (LHC) has been forced out of action for at least two months while engineers probe a fault in one section of the tunnel.

A helium leak in one sector of the LHC's underground tunnel has forced a delay of two months until the first particle collision experiments can be made. Image: CERN.

The LHC is the world’s largest and highest energy particle accelerator, designed to collide opposing beams of protons at extremely high energy to recreate conditions in the Universe shortly after the big bang. The LHC is buried 100 metres underneath the French-Swiss border near Geneva. The first beams were fired successfully around the 27 kilometre circuit over a week ago (read our report here) but the giant experiment has now been powered down following some mechanical setbacks.

First a 30-tonne transformer designed to cool part of the collider broke, although the cryogenics system was put into standby mode to maintain the cool temperatures while the problem was fixed. Then, on Friday, a faulty electrical connection between two magnets reportedly melted, leading to the loss of vacuum, and a devastating one-tonne leak of liquid helium into the tunnel.

Temperatures soared by a hundred degrees causing meltdown of magnets designed to operate at -271 Celsius, just above absolute zero. The LHC’s magnets control the acceleration of the particle beams around the collider.

Since workers are not permitted to enter the underground experiment while it is in operation, there was no danger to human lives by the helium leak. But in order to make the necessary repairs the machine will have to be warmed up for engineers to enter the complex, and then cooled back down again to begin the experiments. This translates into at least two months down time for the LHC, meaning that the first attempts at colliding particles will likely be put back to the end of the year at the earliest.

Once the particle beams start colliding, physicists hope to answer some of the Universe’s biggest questions, such as the origin of mass, the probability of extra dimensions and the nature of dark matter. Read more about the science behind the LHC in our report Powering up the world's biggest physics experiment.