Golden Jubilee Photos: The great LHC industrial adventure

Moving a project from the drawing board into production is never an easy task. With a project as sophisticated, innovative and grandiose as the LHC, it becomes a major challenge lasting several years.

When the LHC was approved in December 1994, the teams knew that a colossal task lay ahead of them. The LHC Division was created in 1996 and quickly saw its staff numbers rise to around 300 full-time employees.

One of the major difficulties was the move from the prototype phase to industrial series production, involving, among other things, the production of 1250 fifteen-metre-long superconducting dipole magnets forming the very heart of the machine. As an illustration of the complexity involved, these magnets are made up of windings of superconducting cables, each comprising some thirty strands approximately 1 millimetre in diameter, each strand in turn containing up to 9000 niobium-titanium filaments ten times finer than a human hair. The 7000 kilometres of cable needed to equip all the magnets are produced in six different plants across the world to almost identical specifications.

In order to meet this challenge, CERN transferred its technological know-how to industry right from the very earliest prototyping phases. To help refine the various technical parameters, an initial test string comprising 10-metre long magnets was assembled and commissioned at the end of 1994. The first prototype 15-metre (nominal length) magnet was successfully tested and reached the desired magnetic field of 8.3 tesla in June 1998, and the first pre-series magnets were delivered at the end of 2000. A second test string comprising 15-metre-long magnets was then inaugurated in 2001. Using this curved 120-metre-long test facility simulations could be made of a whole accelerator segment and the final technical choices could thus be validated.

The difficult transition to full-scale series production still lay ahead, and much work had to be done with the contractors involved, both for the manufacture of the components and for the production of the magnets. Similarly, the systematic testing needed for the technical acceptance of the magnets called for the installation of complex facilities, and a cryogenic plant fitted with 12 test benches is now operating around the clock. Production and cryogenic testing are now up to cruising speed, and this week the 500th dipole was acceptance-tested at CERN, marking the completion of more than three of the machine's eight sectors.

The construction of the LHC cryogenic system is another major challenge, as the machine will operate at -271°C, two degrees above absolute zero. All the 4.5 K helium refrigerators have been acceptance-tested, and the 1.8 K cryogenic plants, custom-designed for the LHC, are now being built and installed.

The major tasks remaining today are the installation and connection of the machine components in the tunnel and the commissioning of the associated technical systems. The LHC teams are now working flat-out to ensure that the machine produces its first beam collisions in the summer of 2007.