CERN Accelerating science

On 30 March 2010, exactly ten years ago, a metaphorical champagne bottle was smashed across the bow of the Large Hadron Collider (and several non-metaphorical ones were popped) as CERN’s flagship accelerator embarked upon its record-breaking journey to explore strange new worlds at the high-energy frontier: it collided protons at an energy of 3.5 teraelectronvolts (TeV) per beam for the first time. Since then, the largest scientific instrument ever built has enabled scientists to study a variety of physics phenomena, with its crowning achievement being the discovery of the Higgs boson in 2012.

The LHC wasn’t built just to find the Higgs boson – or prove that it didn’t exist! Over the last ten years, it has allowed scientists to test the Standard Model of particle physics with higher precision than ever before, demonstrating the theory’s robustness. In addition to the proton–proton collisions that are the LHC’s staple, scientists have used collisions of lead nuclei to recreate and examine the conditions that prevailed in the very early universe, when quarks and gluons existed freely. And the Higgs boson itself has brought entirely new perspectives to physics – an elementary particle with no intrinsic angular momentum, the first of its kind.

The path to proton–proton collisions at the teraelectronvolt scale – whose story goes as far back as 1977, when such a machine was first conceived – was fraught with challenges. No hadron collider of this size and energy had been built before, and technical and scientific expertise had to be cultivated to bring it to fruition. Global collaborations were formed to design and build the detectors at each of the four collision points around the ring.

Proton beams flew through the machine for the first time on 10 September 2008, but an electrical fault only nine days later put the accelerator out of action for over a year. The first low-energy collisions were achieved on 23 November 2009. A week later, the LHC took over the mantle from Fermilab’s Tevatron as the world’s highest-energy collider, achieving 1.18 TeV in each beam. The following March, it left the shallow waters and entered uncharted territory by colliding beams at an energy of 3.5 TeV per beam. Tears of joy and relief accompanied thunderous applause in the CERN Control Centre and the experiments’ control rooms. That Tuesday, when all four of the LHC’s big detectors – ALICE, ATLAS, CMS and LHCb – saw high-energy collision debris for the first time, was the culmination of over 30 years of dreams, plans and dedication. The first papers showing early results were presented days later and, within a few months, the LHC had helped “rediscover” Standard-Model particles that had originally taken decades to find.

In the ten years since, we have witnessed the awesome capabilities of not only the LHC but also the detectors that collect data from the collisions. While the accelerator has performed beyond expectations, so too have these experimental apparatuses, receiving far greater collisions every instant than they had been designed for and filtering out the interesting ones for analysis. The collaborations operating them have published hundreds of scientific papers using data that are unique in every sense.

The LHC’s saga, though, has just begun. The machine is expected to operate until the end of the ’30s and nearly 95% of the LHC’s promised data volume is still to come. However, the analysis of the data collected thus far – in particular phenomena associated with the Higgs boson – has already begun to show where a future accelerator should point its bow.

In the coming weeks, to mark the first ten years of one of humanity’s greatest scientific endeavours, we will publish a series of features on home.cern covering the physics results that have shaped our understanding of the universe – from probing the Standard Model and the early universe, to the new vistas that the Higgs boson has opened up, to the mysteries of dark matter and more. Celebrate ten years of LHC physics with us.

Meanwhile, the celebrations have already begun: the latest issue of the CERN Courier has several stories that might interest you. Bang, beam, bump, boson describes life at the helm of the LHC; A labour of love focuses on the lives of the experimentalists operating the gigantic detectors; and LHC at 10: the physics legacy provides an in-depth look at the new knowledge we have gained from theory and experiment.