Beam sent around Large Hadron Collider
The operators of the Large Hadron Collider have successfully sent a beam of protons around the ring of the world's largest particle collider.
It is the first time the Large Hadron Collider, or LHC, has been operational since September 2008, when an electrical connection in the collider's magnets melted, causing a tonne of super-cooled liquid helium to leak into the tunnel.
CERN, the European Organization for Nuclear Research, announced the success on Twitter on Friday afternoon ET.
"We have completed the ring!" read the post on the social networking and microblogging site.
The operators of the LHC will attempt to create a stable circulating stream of particles early Saturday morning.
The accelerator is designed to smash subatomic particles into each other at high speeds in order to break them down and allow the discovery of smaller, more fundamental particles.
CERN says they will attempt this month to smash protons at an energy level of 3.5 tera-electron volts (TeV), or 3.5 trillion electron volts. The collider was built to move particles at twice those energies.
The LHC is housed in a 27-kilometre tunnel 100 metres underground, forming a ring that straddles the Franco-Swiss border on the outskirts of Geneva.
It is expected to be the most powerful tool yet for physicists hoping to uncover the secrets behind the laws of the universe, both on the tiny scale of quantum mechanics and the huge domain of galaxies and black holes.
The collider has been plagued with problems, most recently a power outage blamed on a piece of bread dropped by a passing bird.
In October, a man reportedly employed at CERN was one of two brothers arrested in France for suspected al-Qaeda links.