Carleton physicists are among a group of scientists who have observed a phase of matter that is thought to have existed in the earliest moments of the universe.
Members of the ATLAS program, a collaboration of more than 3,000 scientists and researchers at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland, detected quark-gluon plasma, a phase of matter comprised of tiny particles that combine into larger particles to form atoms.
Physicists theorize that at a fraction of a second after the Big Bang, the universe was made entirely of quark-gluon plasma. It has not been observed in the 14 billion years since. The discovery is key to understanding the evolution of the universe, according to the ATLAS project website.
The ATLAS team used CERN’s Large Hadron Collider (LHC), a giant particle accelerator 27 kilometres long, to smash lead ions into one another. As the ions collided, quarks and gluons moved away from the collision point, forming separate “jets.”
ATLAS collaborators were able to observe the jets losing momentum as they passed through a hot, dense matter thought to be quark-gluon plasma, in a process called jet quenching.
Devices called liquid argon calorimeters played a vital role in observing jet quenching. These calorimeters measure the energy from particles moving through the LHC.
Components for the calorimeters used in the ATLAS project were built in the basement of the Herzberg building on Carleton’s campus, according to Gerald Oakham, professor of physics at Carleton and leader of the Carleton ATLAS team.
“Carleton has a long history of manufacturing components for these detectors, so we had a lot of experience with them,” Oakham said. The team also includes Carleton associate professors Manuella Vinctor and David Asner.
An ATLAS paper on the experiment shuffled past the standard peer review process and was published in the scientific journal Physics Review Letters Nov. 26, hours after jet quenching was observed. The review process normally takes weeks, according to Rob McPherson, physics professor at the University of Victoria and spokesperson for the ATLAS-Canada collaboration.
“They reviewed it and decided it was important enough to publish immediately. The American journal accepted it within a few hours, on Thanksgiving Day in the United States — it’s a bit unusual,” McPherson said.
Members of the program were delighted at the detection of quark-gluon plasma, but were reluctant to say what kinds of innovations it could spur.
Particle accelerators are used in medical treatments, according to McPherson. For example, the accelerators blast protons directly into tumors for the treatment of cancer.
Discoveries made at the LHC particle accelerator could spill over into fields such as nuclear medicine, according to McPherson.
“The translation of fundamental discoveries that one makes into everyday life is quite a long process, but what goes much more quickly is developing the technology do these experiments,” Oakham said.