LHC to run for longest continuous period

The world's most powerful particle accelerator will soon be turned on for almost two years, running at half-power in the run-up to a full-power phase
Written by David Meyer, Contributor

The Large Hadron Collider is about to enter its longest continuous operational period, in preparation for full-strength particle-smashing.

On Wednesday, Steve Myers, the LHC's director for accelerators and technology, blogged that Cern had decided last week to run the giant particle collider for 18-24 months at a collision energy of seven tera-electron-volts (TeV) — or 3.5 TeV per beam — with the powering-up phase starting later this month.

After that, the LHC will "go into a long shutdown in which we'll do all the necessary work to allow us to reach the LHC's design collision energy of 14 TeV for the next run", Myers wrote.

The LHC is the world's most powerful particle accelerator, designed to smash two beams of protons into each other at unprecedented energies around a 27km-long tunnel under the Franco-Swiss border. The aim is to learn more about physical laws and the nature of matter.

The machine was first turned on in September 2008, although it has since suffered a string of mishaps, such as a faulty transformer that temporarily halted the project in 2008, and a baguette — apparently dropped by a bird — that caused a minor power cut in 2009.

Cern, which runs the LHC, has since used the machine to set a world record for particle acceleration — in November 2009, it reached a beam intensity of 1.18 TeV.

Cern's traditional approach for its particle colliders has been to run the machines during the summer, then shut them down in the winter. This is largely due to the cost of energy — when fully operational, Cern's colliders use about as much energy as the nearby city of Geneva, and electricity is cheaper in summer than it is in winter.

However, Myers wrote, this seasonal model may not apply to the LHC.

Unlike its predecessors, the LHC is a cryogenic facility with lengthy cool-down and warm-up phases at the start and end of its operation periods. As further work is needed to prepare the LHC for operation at energies above 7 TeV, Myers wrote, this leaves Cern with two options: run the machine for a few months now then schedule successive short shut-downs to gradually increase the energy, or run it for a long time now and undergo a single long shut-down before turning it back on at full energy.

"A long run now is the right decision for the LHC and for the experiments," Myers wrote. "It gives the machine people the time necessary to prepare carefully for the work that's needed before allowing 14 TeV. And for the experiments, 18 to 24 months will bring enough data across all the potential discovery areas to firmly establish the LHC as the world's foremost facility for high-energy particle physics."

Cern spokesman James Gillies told ZDNet UK on Thursday that the team was on schedule to get beams circulating on 20 February. Collisions at 3.5 TeV per beam will probably start taking place sometime in the first half of March. He said this run would be for two years at the most, followed by a year-long shutdown for upgrades before the full-strength switch-on.

Asked about the financial implications of running the LHC during winter, Gillies explained that the machine already has to consume some energy during downtime anyway, as it needs to be kept cool.

Gillies also pointed out that Cern uses nuclear energy in the summer and hydro energy in the winter. Although hydro is pricier, it is also more flexible, making it more appropriate for the time of year when domestic heating is used.

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