An incident occurred on Friday September 19 at the mid-day, during the operation (without beam
particles) of the last LHC sector (sector 3-4) for operation at 5 TeV. The incident caused a high helium leak in the tunnel.
Preliminary investigations indicate that the origin Most likely the incident is a electrical connection fault between two magnets. This connection has probably melted in the presence of strong power, leading to a mechanical failure in the system. Under the strict rules of Security force at CERN no nobody was in danger.
A thorough investigation is underway but it is already clear that the sector should be warmed so that repairs can be made. This implies a break of at least two months operation of the LHC. For the same type of failure, which is not uncommon on machines not superconducting, the repair time would be a few days.
In this case, it will indeed cool new superconducting magnets in dipole below 2 K, which will take time given some have reached a temperature of little distant 100 K.
