CERN Large Hadron Collider to Restart Late 2009
Damage from Fall 2008 LHC Accident Required Extensive Repairs
Nov 1, 2009
The CERN Large Hadron Collider (LHC) opened with considerable fanfare on September 10, 2008. Only nine days later, an accident with one of the magnets forced CERN to shut down the LHC. CERN physicists and engineers originally thought that they could repair the damage and restart the Large Hadron Collider by about April, 2009.
Like many large science projects the LHC restart was delayed.
September 2008 LHC Accident
It took CERN scientists and engineers a while to identify the cause of the September 2008 failure, but it turned out to be an electrical splice between superconducting cables. The splice was soldered improperly.
A poorly soldered electrical connection does not sound very serious, but in this case repairing the collateral damage cost CERN 37 million US dollars in addition to regular staff salaries. To avoid another similar shutdown CERN technicians have tested 20,000 LHC electrical splices and repaired three.
In September 2008, the faulty electrical connection caused a liquid helium leak and damaged 53 of the LHC's 1232 superconducting magnets to the point that they needed to be replaced with spare magnets.
After replacing the superconducting magnets, CERN engineers had to retrain them. Retraining the LHC magnets involves slowly increasing their electric currents to allow the coils to settle into their final shape. About one third of the Large Hadron Collider superconducting magnets required retraining, which is a time consuming process.
Completing the necessary repairs to the Large Hadron Collider took longer than originally anticipated, but the LHC is finally scheduled to restart in November 2009.
Restarting the LHC in November 2009
Because winter energy costs are so high, the Large Hadron Collider will not normally run during the winter. The November restart will consume an additional 21.5 million US dollars in electricity costs.
CERN plans to restart the LHC at lower energies than the normal operating energy. The LHC will start with an initial energy of 450 Gev (giga electron volts, giga=E9). CERN scientists then plan to slowly increase the LHC energy to 3.5 Tev (tera electron volts, tera=E12).
Particle physicists will perform experiments and debug the LHC at 3.5 Tev. If all goes well physicists can increase the Large Hadron Collider energy to 5 Tev in 2010. Eventually particle physicists hope that the Large Hadron Collider will finally reach its design energy of 7 Tev.
When all the repairs and commissioning experiments are complete, the CERN Large Hadron Collider can finally start looking for the elusive Higgs boson, aka the God particle.
Further Reading
Schwarzschild, B. "Mishap Shuts Down LHC Until April" Physics Today, November, 2008, p. 24.
Feder, T. "Mostly Recovered, the LHC Readies for Restart" Physics Today, October, 2009, p. 25.
CERN LHC News Updates for the latest on the Large Hadron Collider
 |
