Engineering news
The Large Hadron Collider, the largest and most powerful particle accelerator in the world, is set to be re-started after two years of upgrades and maintenance.
Scientists in charge of the Large Hadron Collider revealed that last weekend test beams of proton particles were successfully sent into the machine's 27km (16.7 miles) of circular tunnels.
In about a fortnight's time they hope to start circulating the beams as the gradual process of building up energy begins, but it is likely to be another two months before the target energy level of 13 tera electron volts (TeV) is reached.
Two years ago the LHC team at Cern, the European Organisation for Nuclear Research, discovery the Higgs boson, an elementary particle that gives other particles mass.
This time their sights are set on dark matter, the invisible, undetectable material that makes up 84% of the mass of the universe and binds galaxies together, yet whose nature is unknown.
The projects' director general Professor Rolf Heuer said: "It will start some time this month - I hope in maybe two weeks we will see that we get the first protons circulating, but it will take some time. We have learned to be patient."
He added: "It is practically a new machine. You have to be very careful about switching on such a high- power laser, so to speak, because there's enough power to melt one tonne of copper, and I don't want to do that."
During the upgrade, 18 of the LHC's superconducting magnets, which steer the particle beams, were replaced and more than 10,000 electrical connections between the magnets strengthened.
After its re-fit, the LHC should be able to reach an energy level of almost double the 8TeV that produced the Higgs boson.
Besides looking for dark matter, the scientists will want to learn more about the Higgs boson, he said.