In a 17-mile tunnel located underneath France and Switzerland, the Large Hadron Collider — the largest high-energy particle accelerator in the world — underwent its first beam collision early last week, marking a quantum leap toward testing current models of physics.
Researchers at the European Organization for Nuclear Research — some of whom are from the University of Michigan — hope the energy generated by the LHC will produce collisions between subatomic particles and answer key questions surrounding the creation of matter and other dimensions.
“It’s going to be an exciting few months ahead,” said J. Chapman, a professor emeritus of physics at the University and one of the LHC researchers.
The LHC has the potential to accelerate beams of particles along its 17-mile circumference in just microseconds, Chapman said. The head-on collisions produce an array of particles, and the after-effects produced by the collision are captured by detectors, allowing researchers to analyze data long after the particles decay.
Physics Prof. Bing Zhou said the particles in the beam must be held in the precise orbit by magnets in order for head-on collisions to occur, adding that one interesting event is observed about every 100 trillion collisions.
“We’re looking for whatever nature provides,” Chapman said. “We’re using the well-known equation from Einstein. So if you put enough energy into the collision, you can make anything that nature manifests.”
The University is the largest contributor to the development of the ATLAS detector, one of the four detectors situated along the 17-mile stretch, Zhou said. The ATLAS serves as a general-purpose measure of the particle collisions.
Zhou said University researchers helped design and operate the ATLAS detector at CERN and that much of the data gathered by ATLAS is processed at the University.
Chapman said the accelerator is currently running at low collision rates and will steadily increase once physicists and workers at CERN become more familiar with how it works.
“At the moment, we’re not looking at very many events of the interesting type,” he said. “It will become very exciting when we get to higher collision rates and that is where the interesting physics is.”
Chapman said reaching the LHC’s full performance capacity is a step-by-step process. The current challenge is to ensure that everything is functioning properly. He added that over the next few weeks, researchers will begin to ramp up the number of proton bunches — groups of positively charged particles — in each beam.
Zhou said the ultimate goal of creating the high-energy collisions is to uncover features of the Standard Model in particle physics that have thus far only been the subject of speculation.
The model, she said, theorizes that all particles with mass are created from an interaction with the Higgs boson — a theoretical particle that many researchers hope to detect through the LHC collisions.
“Only when you have energy high enough … can you recreate such a particle in the laboratory,” Zhou said.
Chapman said the discovery of the Higgs boson would require considerable preliminary analysis but is feasible through the LHC.
“The first thing we’ll do is to look for those things we already know about,” Chapman said. “Then (we’ll) begin to look for things that are speculated but haven’t been seen.”
Chapman added: “This machine is our best guess as to how to do that.”