Today the Large Hadron Collider (LHC for short) will close its doors for two years to make much-needed upgrades, possibly to start exploration into the existence of dark matter and extra dimensions.
The LHC represents everything science should be. Physicists and Engineers from over 100 countries joined together to build the $9 billion particle collider with the sole purpose of answering fundamental questions of the universe. And, boy, did they. Even with a set back only nine days after opening–a magnetic quench that took over a year to fix–the machine has detected new fundamental particles, the Higgs boson being the most important.
Physicists have been using the Standard Model since the 1970s to explain all sorts of natural phenomena, with the catch that no one has proven the model to be experimentally correct. The LHC tests fundamental aspects of the Standard Model, but doesn’t take a side on whether it is right or wrong. There are even some scientists out there that hope the LHC finds something new and unexpected to turn the physics community on its head. But last November, the LHC (tentatively) found what the majority of scientists had crossed their fingers for: the Higgs boson, the particle that gives everything mass.
It’s interesting to think that while we were building computers and walking on the Moon, no one knew why particles had mass, just that they did. With the Standard Model, scientists believe that the particles we know–electrons, quarks, etc.–get their mass from interaction with a Higgs field and the amount of interaction with that field determines the mass; more interaction means a more massive particle.
But how do we know a Higgs field exists? If the field is given enough energy to “excite” it, a Higgs particle will pop into existence. Because the particle is so massive, it quickly decays–in fractions of fractions of a second–into two streams of electrons and hadrons, the building blocks of protons and neutrons. The LHC hopes to see these decay streams after smashing protons and bare lead nuclei together at ultra-high speeds. The decay streams will only be seen for a small fraction of collisions–1 possible Higgs boson for 10 billion collisions–and many decays need to be observed to guarantee a discovery. But with around 600 million collisions per second, the LHC should be able to see roughly one event every half hour.
Currently, scientists at the LHC think they saw enough decays to confirm the existence of the Higgs boson, though it will take a while to analyse the massive amount of data coming from the collider. Now is the opportune time for the LHC to shut down and make upgrades. While we won’t hear of any experiments for close to two years, there is still much to look forward to from the outcome of past runs.