After achieving record beam energies last month, physicists at the Large Hadron Collider (LHC) have successfully carried out the first collisions in this new regime.
In this game of “the bigger the better,” the LHC is now colliding protons at 8 Tera-electronvolts (TeV) — a huge step toward peeling back the frontiers of high-energy physics, culminating in the increasingly likely confirmation of the Higgs boson.
In the April 5 announcement, CERN said, “the LHC shift crew declared ‘stable beams’ as two 4 TeV proton beams were brought into collision at the LHC’s four interaction points … The collision energy of 8 TeV is a new world record, and increases the machine’s discovery potential considerably.”
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For the last year, the LHC has been running at 3.5 TeV per beam, allowing physicists to familiarize themselves with the machine operating in this previously unattainable energy range. By slamming two counter-rotating beams of protons at 3.5 TeV apiece, collision energies of 7 TeV have been possible.
At 7 TeV, the LHC has revealed some tantalizing hints of the Higgs — a much sought-after subatomic particle that is theorized to endow all matter in the Universe with mass.
By amping-up collision energies higher by 1 TeV, physicists hope to generate more Higgs particles (if they do indeed exist) so they produce a strong enough signal that will leave no ambiguity.
But it’s not all just about the Higgs. By recreating the conditions of the Big Bang for the briefest of moments as protons collide, it is hoped that higher collision energies will help us glimpse particles hypothesized to exist beyond the Standard Model of physics. The “Standard Model” Higgs is the last piece of this puzzle, but there are many theories that it cannot account for — such as why gravity doesn’t “fit” with the Standard Model.
“(Supersymmetric particles) would be produced much more copiously at the higher energy. Supersymmetry is a theory in particle physics that goes beyond the current Standard Model, and could account for the dark matter of the Universe,” the CERN statement continues.
“Standard Model Higgs particles, if they exist, will also be produced more copiously at 8 TeV than at 7 TeV, but background processes that mimic the Higgs signal will also increase. That means that the full year’s running will still be necessary to convert the tantalizing hints seen in 2011 into a discovery, or to rule out the Standard Model Higgs particle altogether.”
It goes to show that, although there are some hints of the Higgs, boosting LHC energy may still disprove its existence. Either way, it seems an answer is close. The LHC will run until the end of 2012, when it will be shut down in preparation for an even bigger amplification of collision energy — culminating with the designed LHC maximum collision energy of 14 TeV by the end of 2014.
Image: A graphical display of a particle collision in the ATLAS experiment of the LHC. Credit: CERN