AFTER six months of delay and to near-universal relief, Europe鈥檚 next mammoth particle collider has finally been given the go-ahead. Last week, the 19 member nations of CERN, the European centre for particle physics near Geneva, approved construction of the Large Hadron Collider (LHC).
Physicists believe the machine will reveal how fundamental particles 鈥� the building blocks from which all matter is made 鈥� acquire their mass. The collider鈥檚 future had been in limbo since June, when Britain and Germany refused to sign on to the project (This Week, 2 July). 鈥淭oday鈥檚 decision has assured a great future for world particle physics and for CERN,鈥� said a relieved Chris Llewellyn-Smith, CERN鈥檚 director-general. The approval means he can start negotiating with the US and other countries that are not members of CERN, which are being asked to help fund the project to the tune of 拢240 million.
Britain and Germany had been worried about the LHC鈥檚 拢1.25 billion price tag, and feared that this figure might be revised upwards. To accommodate these concerns, CERN鈥檚 overall budget will be held level until 1998. After that, the laboratory鈥檚 budget will grow at only 1 per cent a year.
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Because CERN had assumed that its budget would grow by around 2 per cent each year, to account for inflation, these decisions will slow down construction of the LHC. Under last week鈥檚 plan, experiments on an 鈥淟HC minus鈥�, running at about two-thirds the machine鈥檚 maximum energy, would start in 2004. The collider would be stepped up to its full potential by adding more of the magnets used to steer its beams of protons round the machine鈥檚 circular tunnel, by 2008 鈥� four years later than physicists had hoped. The LHC could, however, start working at its full energy in 2005 if nonmember countries provide the full sum that CERN is asking them for.
Despite everything, most physicists are simply relieved that the LHC is now approved. 鈥淲ithin the first few years, there will be plenty of significant physics to be done,鈥� says Peter Jenni, who heads the team working on ATLAS, one of two huge particle detectors planned for the LHC. It should be possible, he says, to generate large quantities of top quarks 鈥� the elusive particles that may already have been found in small numbers at Fermilab in Illinois. But at the lower energy, Jenni rates the chances of finding the LHC鈥檚 main quarry 鈥� the hypothetical Higgs boson which is believed to be the carrier of mass 鈥� as 鈥渇ifty-fifty鈥�.