Following the news of a helium leak within a tunnel at the LHC, CERN has announced that a restart of the accelerator complex is likely to occur in early spring 2009.

Investigations at CERN following the large helium leak into sector 34 of the LHC tunnel have indicated that the most likely cause of the incident was a faulty electrical connection, between two of the accelerator’s magnets.

Before a full understanding of the incident can be established however, the sector has to be brought to room temperature and the magnets involved opened up for inspection. This will take between three to four weeks.

The time necessary for the investigation and repairs precludes a restart before CERN’s obligatory winter maintenance period, bringing the date for restart of the accelerator complex to early spring 2009. LHC beams will then follow.

Those at CERN are quick to point to the perceived success already achieved at the LHC, as a means of softening the blow is dealt. CERN Director General Robert Aymar commented, “Coming immediately after the very successful start of LHC operation on 10th 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.”

Particle accelerators such as the LHC are unique machines, built at the cutting edge of technology and with immense complexity. Each is its own prototype, and teething troubles at the start-up phase are therefore always possible, if not inevitable.

Peter Limon, responsible for commissioning the world’s first large-scale superconducting accelerator in the US, explained, “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.”

CERN previously reported the incident, which occurred at mid-day on 19th September during commissioning of the final LHC sector. The incident occurred during commissioning, without beam, of the final LHC sector (sector 34) at high current for operation at 5 TeV and resulted in a huge helium leak.