One of the world’s most expensive ever scientific experiments has been brought to a temporary halt after significant damage was caused to the Large Hadron Collider (LHC) in Geneva last week.

The £3.6 billion “atom-smasher” is to undergo repairs following an electrical failure which caused over a tonne of liquid helium to spill into the machine’s 17 miles of underground tunnelling at the European Organisation for Nuclear Research (CERN) base. It will take approximately two months before the LHC will be operational, meaning that it will not be ready until after its obligatory winter maintenance period.

CERN Director General Robert Aymar said: “Coming immediately after the very successful start of LHC operation on 10 September, this is undoubtedly a psychological blow.

“Nevertheless, the success of the LHC’s first operation with beam is testimony to years of painstaking preparation and the skill of the teams involved in building and running CERN’s accelerator complex. I have no doubt that we will overcome this setback with the same degree of rigour and application.”

Investigators at CERN believe that a faulty connection between two super-conducting magnets was responsible for the damage. However, scientists are unable to physically assess and repair the damage until the temperature in the tunnel is brought up from nearly absolute zero (-273.15⁰C) to room temperature. It is believed this will take between three and four weeks. Once repairs are completed, another four weeks or so will be required to lower the temperature back down again.

CERN do not run the LHC over the winter period because of the huge electricity consumption required to run the experiment – when operational, the super-collider draws approximately the same amount of power as the entire city of Geneva. As a result, the experiment will be powered down until spring 2009.

Peter Limon, who helped commission the world’s first large-scale superconducting accelerator said: “The LHC is a very complex instrument, huge in scale and pushing technological limits in many areas. Events occur from time to time that temporarily stop operations, for shorter or longer periods, especially during the early phases.”

The LHC super-collider is the largest such project ever to be undertaken and scientists hope it will help shed light on the most fundamental questions in the world of particle physics. It is believed that the conditions created inside the LHC will be comparable to those which occurred immediately after the big bang at the start of the universe approximately 13.7bn years ago.