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LHC boffins crank beams to 3.5 TeV redline

'Dump cores' catch and stop moving aircraft carriers

By Lewis Page, 19 Mar 2010

Big news from the Large Hadron Collider (LHC) overnight. The titanic proton-punisher has once again smashed all records to achieve the most powerful particle beams ever generated by the human race, at energies of 3.5 Tera-electron-volts - the maximum redline power at which the mighty machine can currently be safely run.

Slide from LHC 0830 morning briefing Friday 19 March 2010.

Uncontrolled emotion was shown by the scientists

The LHc narrowly nudged ahead of the planet's second-most-puissant atomsmasher towards the end of last year's proton billiards season, generating 1.18 TeV beams. The rival Tevatron, located in America, can manage only 0.98 TeV: last night's 3.5 TeV beams at the LHC have now moved particle physics firmly into a new league.

The LHC is actually designed to be capable of still more outrageous 7 TeV beams, which can be crossed over almost head-on to produce unimaginably violent particle collisions at 14 TeV energies. However, following the machine's original fire-up in 2008, a blown power connection led to a disastrous liquid helium superfluid explosion mishap which flung multi-tonne magnet pipes about like cardboard poster tubes and crippled the Collider for months.

Following that incident, engineers painted the new half-power 3.5 TeV redline on the Big Dial. The plan is to work within this limit this year, and then strip out and replace all the relevant power connections around the entire 27km underground tunnel which houses the LHC. This will be a long job, so CERN boffins are keen to get in a good run at 3.5 Tev first so as to pile up some data for their mighty supercomputing grids to crunch in the meantime.

It's worth noting that last night saw no actual particle collisions as such. However, in the natural course of things it's not safe to simply switch off the magnets having created such powerful beams. A full 7 TeV beam contains as much energy as a Royal Navy aircraft carrier steaming at 12 knots; thus a half-power 3.5 TeV one like last night's has as much energy as the same huge ship going at 8 knots (kinetic energy being proportional to the square of velocity).

Need to catch and stop a moving aircraft carrier made of lightspeed protons? Get yourself a Dump Core

Once the beams are up, that energy has to go somewhere in the end: if a single magnet were to fail, for instance, a terrific blast of energy would leave the Collider's ring at that point with consequences much the same as if HMS Invincible had suddenly popped out of nowhere and rammed the tunnel.

Thus it is that the LHC is equipped with specially constructed "beam dump" caverns a little way off the main circuit, containing huge bus-sized "dump cores" made of graphite, cased in heavy steel, water cooled and then further wrapped in 750 tonnes of concrete shielding. If a magnet mishap looks to be brewing - or if, as in last night's case, beams simply need to be got rid of safely - the screaming 27km loop of lightspeed particles is diverted into one of these.

"Beams dumped properly", control-room boffins noted laconically at a briefing this morning - indicating that the subterranean graphite safety nets had managed to catch and stop the notional aircraft carriers without ripping free of their moorings.

Strictly speaking, as keen amateur LHC-watcher Chris Stephens noted, the dumps were technically 3.5 TeV collisions, so the LHC has also broken collision-energy records last night - albeit not inside a detector instrument, so no scientific benefit resulted.

Furthermore, following last year's record-breaking 1.18 TeV beams the first 2.36 TeV collisions occured within days. Thus we might well expect to see some truly awesome, unprecedentedly matter-wracking 7 TeV proton pileups in the near future. CERN PRs are planning a big mainstream press splash at the end of the month, but we're hoping that the frontline boffins (covered every step of the way by us here at the Reg, and even more closely by the fan club at the LHC Portal) will beat the press office to the punch as they have so many times before. ®

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