After a year plus of being repaired, the Large Hadron Collider (LHC) circulated its first beams late last Friday, and commenced with low energy collisions today!

After checking that each section could curve particles as expected, as well as checking to make sure each beam dump worked, CERN finally circulated counter rotating beams about the LHC. Once the beams were in place, they began to work on beam lifetime, going from thirty minutes to a still theoretical ten and a half hour lifetime. (This will be easily reached.) Once the beams had sufficient lifetime in the collider, they brought the beams together in a collision! Holy crap!

CERN is colliding the beams in each one of the massive devices instruments at a time, giving them the chance to use real world data to perform shakedown cruses, as you will. As of this writing, I am aware of collisions in ATLAS, the CMS, and rapidly coming up in TOTEM, ALICE, and LHCb, with the others to follow shortly. Around Christmas, after instrument testing and shakedown, the beams will be ramped up from their current energy of 450 GeV to 1.2 TeV, for a center of mass energy of 2.4 TeV, a record setting energy.

Congrats to all involved, and a hearty ho-ho to all. Now the real work of discovery begins.

Links for more information:

CERN Press Release

A Cosmic Variance Blog Post

A different Cosmic Variance author, with more information

CMS Commentary