Large Handron Collider (LHC) stopped by Small Dry Joint (SDJ)

THE Large Hadron Collider (LHC), possibly science's greatest ever project, was undone in September by one badly soldered joint. With 10,000 such joints around the accelerator's ring, it is proving a struggle to check them all in time to restart this autumn as hoped.

A splice between two sections of superconducting cable melted when the current was turned up. As well as repairing the one that failed, engineers have so far found and fixed 20 slightly under-par splices. It is a slow process as each of the LHC's eight sectors must be gently warmed from its 1.9 kelvin operating temperature to about 300 K to be checked and repaired.

The repairers are now testing if they can check the splices at a moderately cool 80 K. "We'll know by Tuesday," says LHC technical director Steve Myers. If so, the last three sectors can be screened much more quickly. Any urgent repairs will delay the start-up, but less serious faults could be left and the LHC switched on anyway, perhaps at reduced energy.

It is an interesting dilemma that, as you approach the atomic layers the technology and physics that bring you there, are starting to break down. This is particularly so for materials and their interconnectivity.