Geneva, 23 November 2009.
Today the LHC circulated two beams simultaneously for the first time, allowing the operators to test the synchronization of the beams and giving the experiments their first chance to look for proton-proton collisions. With just one bunch of particles circulating in each direction, the beams can be made to cross in up to two places in the ring. From early in the afternoon, the beams were made to cross at points 1 and 5, home to the ATLAS and CMS detectors, both of which were on the lookout for collisions. Later, beams crossed at points 2 and 8, ALICE and LHCb.

Its a great achievement to have come this far in so short a time,said CERN Director General Rolf Heuer.But we need to keep a sense of perspective theres still much to do before we can start the LHC physics programme.

Beams were first tuned to produce collisions in the ATLAS detector, which recorded its first candidate for collisions at 14:22 this afternoon. Later, the beams were optimised for CMS. In the evening, ALICE had the first optimisation, followed by LHCb.

This is great news, the start of a fantastic era of physics and hopefully discoveries after 20 years' work by the international community to build a machine and detectors of unprecedented complexity and performance," said ATLAS spokesperson Fabiola Gianotti.

The events so far mark the start of the second half of this incredible voyage of discovery of the secrets of nature,said CMS spokesperson Tejinder Virdee.

It was standing room only in the ALICE control room and cheers erupted with the first collisions,said ALICE spokesperson Jurgen Schukraft. This is simply tremendous.

The tracks were seeing are beautiful, said LHCb spokesperson Andrei Golutvin, were all ready for serious data taking in a few days time.

These developments come just three days after the LHC restart, demonstrating the excellent performance of the beam control system. Since the start-up, the operators have been circulating beams around the ring alternately in one direction and then the other at the injection energy of 450 GeV. The beam lifetime has gradually been increased to 10 hours, and today beams have been circulating simultaneously in both directions, still at the injection energy.

Next on the schedule is an intense commissioning phase aimed at increasing the beam intensity and accelerating the beams. All being well, by Christmas, the LHC should reach 1.2 TeV per beam, and have provided good quantities of collision data for the experiments calibrations.

Nakon velike panike koju su mediji pravili povodom puštanja u rad najvećeg akceleratora na svetu, mali broj ljudi je znao da se LHC zapravo pokvario samo 10 dana nakon puštanja u rad.

Nakon više od godinu dana opravki i podešavanja Large Hadron Collider je ponovo pušten u rad i već su obavljeni i prvi sudari protona.

Potraga za Higsovim bozonom se nastavlja!

hm.

By Stuart Fox

The Baguette Incident: Re-enacted according to eyewitness accounts.  CERN; Bird via Foxypar4/Flickr

The Large Hadron Collider, the world's most powerful particle accelerator, just cannot catch a break. First, a coolant leak destroyed some of the magnets that guide the energy beam. Then LHC officials postponed the restart of the machine to add additional safety features. Now, a bird dropping a piece of bread on a section of the accelerator has, according to the Register, shut down the whole operation.

The bird dropped some bread on a section of outdoor machinery, eventually leading to significant over heating in parts of the accelerator. The LHC was not operational at the time of the incident, but the spike produced so much heat that had the beam been on, automatic failsafes would have shut down the machine.

This incident won't delay the reactivation of the facility later this month, but exposes yet another vulnerability of the what might be the most complex machine ever built. With freak accident after freak accident piling up over at CERN, the idea of time traveling particles returning from the future to prevent their own discovery is beginning to seem less and less far fetched.

Lamont, briefing reporters at the control room yesterday, told the Reg that machinery on the surface - the LHC accelerator circuit itself is buried deep beneath the Franco-Swiss border outside Geneva - had suffered a fault caused by "a bit of baguette on the busbars", thought perhaps to have been dropped by a bird.

As a result, temperatures in part of the LHC's circuit climbed to almost 8 Kelvin - significantly higher than the normal operating temperature of 1.9, and close to the temperature at which the LHC's niobium-titanium magnets are likely to "quench", or cease superconducting and become ordinary "warm" magnets - by no means up to the task imposed on them. Dr Tadeusz Kurtyka, a CERN engineer, told the Reg that this can happen unpredictably at temperatures above 9.6 K.