Above: Photo by Travis Valdez, courtesy of Melissa Mathers
If you’re reading this outside of school, there’s a pretty good chance you really love science. When I was in high school, I spent my summers reading issues of science magazines that I had collected during the school year. I distinctly remember cutting out a big photo of the Large Hadron Collider (LHC) at CERN when it first opened in 2010. I was inspired by the physicists working on cutting-edge science experiments and I pinned their stories to my corkboard. Fast-forward five years, and I’ve completed an undergraduate degree in physics. Now I’m doing graduate research at CERN myself!
The project I’m working with is called ALPHA. That stands for Antihydrogen Laser PHysics Apparatus, which was the name of the team’s first experiment. Our goal is to create and trap antihydrogen and use lasers to study it. Lasers produce light that is completely monochromatic. That means it is made of only one wavelength (colour) of light. Physicists use this unique property of lasers to excite atoms. They shine light with the exact amount of energy the electrons need to jump between energy levels.
Our approach is similar to how atomic physicists have studied regular hydrogen atoms in the past. With only one proton and one electron, hydrogen is the simplest atom. Because of its simplicity, hydrogen has been thoroughly studied. Its physical properties—like mass, charge, spin, and energy levels—are well known.
|The Alpha-2 experimental apparatus, located in the Antimatter Factory at CERN. Click image to enlarge (Travis Valdez, courtesy of Melissa Mathers)
Researchers know a lot less about antihydrogen. It is made of one antiproton (a negatively charged proton) and one positron (a positively charged electron). Particles and antiparticles share all of the same properties, except charge, which has the same value but opposite sign. As we study antihydrogen, we’re interested to see if we measure values that are different than for regular hydrogen. That would be a clear sign there is “new physics” that isn’t explained by the Standard Model.
On the most fundamental level, we are trying to understand why we observe more matter than antimatter in our universe. At the time of the Big Bang, an equal amount of both matter and antimatter should have been produced. But something tipped the scales in favour of regular matter. How do we know? When a particle meets its antiparticle counterpart, their masses are turned completely into energy and they vanish. This process, called annihilation, is governed by the famous equation E=mc2.
If an equal amount of each kind of matter had been created after the Big Bang, everything would have annihilated soon after it was created. The universe would just be leftover energy. But we know that is not the case, because here we are! So our team is trying to find out what happened to all of the antimatter, or why more matter was created than antimatter in the first place. This is called the antimatter asymmetry problem.
Our experimental apparatus, ALPHA-2, is located in the Antiproton Decelerator Hall. Recently, the building was nicknamed the “Antimatter Factory”. There are several other antimatter experiments using the same building, like AEgIS, ASACUSA and ATRAP. They are all aimed at understanding more about antimatter.
Are you interested in antimatter too? Maybe in five more years you’ll be working on one of the projects in the Antimatter Factory, just like me!
News article on the ALPHA project’s research at CERN: