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Into the record book: LEP report on the first collisions at 200 GeV centre-of-mass energy. Credit: CERN

Scientists at the European Laboratory for Particle Physics (CERN) are celebrating a breakthrough which some claim could in principle allow them to produce and begin to characterize the elusive Higgs boson before the end of this year.

Over the past three years, CERN's Large Electron-Positron Collider (LEP) in Geneva, the world's most powerful particle accelerator, has been tuned to deliver higher and higher energy beams. Last week, almost exactly ten years after its first experiments, LEP was pushed beyond its design limits when its colliding beams of electrons and positrons achieved energies of 200 GeV (individual beam energies of 96 GeV were reached in May, and 98 GeV in July).

This achievement could, say some physicists, be sufficient to detect the Higgs boson, the particle physicist's Holy Grail. Recent measurements at LEP predict a mass of around 109 GeV for the standard model Higgs boson — a particle whose existence was hypothesized to explain why all other particles have such a wide range of masses.

Not everyone is confident that the Higgs mass will be quite so low, and the boson may therefore remain elusive until the construction of CERN's Large Hadron Collider. But the response among CERN scientists when LEP hit its energy target “was quite noisy”, says Patrick Janot, the collider's physics coordinator. “We opened all our champagne bottles at the same time.”

Mike Witherell, new director of the US particle physics laboratory Fermilab, describes it as a “great achievement to be able to squeeze so much physics out of LEP”. He adds that the Higgs mass is “so fundamental to our field” that every increase in GeV is very important to home in more precisely on the likely mass.