Large Hadron Collider starts up, produces first collisions

Tagged: Large Hadron Collider, Technology
Source: Ars Technica - Read the full article
Posted: 4 years 20 weeks ago

After a series of complications and setbacks, the Large Hadron Collider sees its first particle-particle collisions after a weekend of furious activity. While these weren't at any significant energy, the milestone marks an important step in getting the mammoth machine up and running and filling in the last space on the particle bingo card.

Boy, you go away for a weekend, and all sorts of stuff starts happening at the biggest science fair the world has ever seen. The CERN collaboration's Large Hadron Collider (LHC) sent beams of protons flying around its 27 km length in each direction over the weekend, and Monday saw them run two beams simultaneously and slam them into one another, producing the collider's first ever particle collisions. It would appear that any time-traveling quantum bird sent by the Higgs boson was unable to disrupt yesterday's run.

Last fall, the LHC team came close to reaching this same milestone, but fell short when a massive quench failure damaged a number of the superconducting magnets that are used to help guide, accelerate, and squeeze the beams of particles as they move around the tunnel. This failure occurred only nine days after the first particles were circulated, but was only one in a series of setbacks that the collider would experience. Broken support structures, helium leaks, and frayed wiring all required that the equipment be warmed up from the frosty operating conditions of 1.8 Kelvin. The most recent mishap involved a bird dropping bread into an electrical transformer. All of this has caused some to speculate that the Higgs boson—the elusive particle that is the basis of mass—is actually causing these failures to occur from the future. Presumably from its fortress of doom and solitude.

In contrast to last year's start-up, this event has occurred with very little press coverage. Some of the US' mainstream news organizations don't even have a headline anywhere on their front page. (Adam Lambert's kiss and Khloe Karadashian's nesting instinct were recent top news items on CNN's main Web portal, which no longer even has a science section.) As a life-long science enthusiast, it saddens me to see so little coverage of a huge milestone in experimental physics. However, this also seems to have cut down on the inevitable "end of the world" speculation that was rampant last year.

As far as science goes, it really took a back seat to engineering, as the first collisions occurred between beams at a low injection energy, 450 GeV. At these energies, proton-proton collisions are statistical rarities, but each of the four main detectors—ATLAS, CMS, LHCb, and ALICE—observed the signature spray of particles. Scientists and engineers expect to have the beams running at energies of around 1.2 TeV by Christmas, and expect to reach world-record energies of 3.5 TeV per beam sometime early next year.

Of course, all this is not for show. Scientists hope to be able to probe conditions similar to those that existed shortly after the big bang, the birth of our Universe. By slamming ultra-high energy particles into one another, they hope to replicate the quark-gluon soup that existed at that time. One of the major goals is a confirmed sighting of the Higgs boson, the last undiscovered particle predicted by the Standard Model physics. It is expected to help us understand why some elementary particles, such as the W and Z bosons, have mass, and why some do not, like the photon or the gluon.

If found, the Higgs boson will fill in the last square on the bingo card of the particle zoo, allowing us to put the standard model on a shelf and not play with it again. But it could be even more exciting if we don't find the Higgs boson. We will be left with a theory that accounts (beautifully, I might add) for every elementary particle we know about except one. We'd have to develop a new theory, one that is capable of explaining everything the current standard model does, with the added capability of explaining mass. And that could prove to be very interesting.

If, and more likely when, the Higgs boson is found, the LHC will still be able to probe things that aren't covered by the standard model. 14 TeV collisions will be unlike anything ever produced in a controlled environment on Earth, although nature does this on a daily basis. Hopefully, barring further challenges from a particle from the future that travels backwards in time (the "All Good Things..." episode of Star Trek: The Next Generation anyone?) the LHC Physics program will be able to start in earnest early next year.