The Large Hadron Collider (LHC), the world's largest and most powerful particle accelerator, has been put into a planned standby mode, restarting in February 2010.
The European Organization for Nuclear Research (Cern) said in a statement that the LHC's “short technical stop” was needed to prepare for higher energy collisions and the start of the main research programme.
The LHC circulated its first particle beams since its restart on November 20, and the first collisions were recorded on November 23.
“Over the last two weeks, the six LHC experiments have recorded over a million particle collisions, which have been distributed smoothly for analysis around the world on the LHC computing grid,” Cern said.
Scientists aim to increase the energy used to smash protons into each other next year far above previous levels in hopes of revealing secrets of matter and the universe.
The $10 billion (SFr10.47 billion) machine, which has made a nearly flawless comeback after being heavily damaged during a start-up failure a year ago, is housed in a 27-kilometre circular tunnel 100 metres under the Swiss-French border at Geneva.
swissinfo.ch and agencies