A look at the damage that halted the LHC

This picture shows the site of the electrical fault that caused the helium leak. A resistive zone developed in one of the electrical connections, creating an electrical arc that punctured one of the helium enclosures around a magnet, according to an analysis by Cern. The warming helium expanded in the vacuum enclosure of the central sub-sector of the pipe, damaging the vacuum barriers separating the central sub-sector from the neighbouring sub-sectors.