One end of the CMS detector during the LHC&39's assembly in 2007.

The Large Hadron Collider, CERN's particle accelerator straddling the border of Switzerland and France, is due to shut down for a major upgrade later than expected, after managers concluded the current rate of operational improvements could reveal new physical phenomena.

The LHC is a mammoth tool best known for its search for the Higgs boson--or more likely, some believe, a suite of them--and its other probes of the bizarre realm of subatomic physics. By colliding particles in two high-energy beams of protons, or more recently lead ions, physicists can re-create conditions present near the Big Bang.

Currently the LHC runs with two beams moving in opposite directions around its 27-kilometer circumference, with the particles in each beam accelerated to an energy of 3.5 tera-electron-volts or TeV.

The eventual plan is to double that to 7TeV, which would detail high-energy physics better. Until recently, CERN had planned to shut down the LHC at the end of 2011 to make the upgrade. Now that plan has been pushed back.

CERN has tripled the amount of data it can gather in 2011 compared with 2010, which leads to the "tantalizing hints" that new physical phenomena could be observed at the 3.5TeV level, CERN said in a statement yesterday.

"However, to turn those hints into a discovery would require more data than can be delivered in one year, hence the decision to postpone the long shutdown," CERN said. Thus, only a short technical pause is planned for the end of 2011.

"With the LHC running so well in 2010, and further improvements in performance expected, there's a real chance that exciting new physics may be within our sights by the end of the year," said Sergio Bertolucci, CERN's research director. "For example, if nature is kind to us and the lightest supersymmetric particle, or the Higgs boson, is within reach of the LHC's current energy, the data we expect to collect by the end of 2012 will put them within our grasp."