As 2015 draws to a close, the ATLAS experiment wraps up its first phase of operation at a record-breaking energy frontier.

As final preparations were made for the start of the Large Hadron Collider's (LHC) Run 2, the ATLAS Control Room was the centre of activity. Here are images from the three days that were landmark events...

The ATLAS & CMS experiments celebrate the second anniversary of the discovery of the Higgs boson. Here, are some images of the path from the LHC's startup to the Nobel Prize, featuring a musical composition by Roger Zare, performed by the Donald Sinta Quartet, called 'LHC'. Happy Discovery Day!

It’s been two years since the ATLAS and CMS experiments at CERN jointly announced the discovery of a new boson consistent with the Higgs particle of the Standard Model. Since then, the Higgs boson has been intensely examined. We’ve measured its spin, its mass, its lifetime, and observed its decay into bosons and fermions. In the next run of the Large Hadron Collider, we hope to learn more about how it interacts with other particles and to make many more precise measurements of its properties. By doing, we hope to extend the limits of our current understanding of the fundamental components of nature, and to seek clues for discovery.

Amazing, incredible, emotional. These are uncommon words for summarizing the annual accomplishments of a particle physics experiment. Yet 2012 has been a fantastically uncommon year for ATLAS, one of the main experiments at CERN: marvellous machine performance, numerous and interesting physics results, plenty of interactions with students and general public, and - last but not least - a major discovery!

Twenty years ago the name “ATLAS” was first used on an official document, the Letter of Intent, to refer to the detector which has been taking data for nigh on three years now, including those data on which the recent Higgs results were based. It has been two decades of growth, development and hard work, resulting in this year’s observation of a Higgs-like particle. All the more reason for the experiment to take a few moments to look back and celebrate.

This Tuesday, if all goes according to plan, will mark the end of a very long journey for many High Energy Physicists. The first 7 TeV Collisions will signal the end of the the commissioning period of the LHC and its experiments.

ATLAS experimenters celebrated today as the first beams circulated the Large Hadron Collider in both directions. While everyone was cheering in the LHC control room, the cheers were echoed in the ATLAS and other control rooms, and in several auditoriums around CERN.