SciTech

Professor works to discover particles that may answer big questions

Thomas Ferguson, a professor at Carnegie Mellon, poses with the Compact Muon Solenoid at the Large Hadron Collider in Geneva, which works to detect subatomic particles such as the elusive Higgs boson particle. The Higgs boson particle is the only predicted particle in the Standard Model that has not yet been discovered. (credit: Courtesy of Thomas Ferguson) Thomas Ferguson, a professor at Carnegie Mellon, poses with the Compact Muon Solenoid at the Large Hadron Collider in Geneva, which works to detect subatomic particles such as the elusive Higgs boson particle. The Higgs boson particle is the only predicted particle in the Standard Model that has not yet been discovered. (credit: Courtesy of Thomas Ferguson)

“What are we all made of?” asked Thomas Ferguson, a professor in Carnegie Mellon’s physics department. Scientists have yet to find a clear answer to this profound and puzzling question. Many fundamental questions have been motivating scientists and engineers for centuries to try to understand how the world around us works. How do forces work? What gives things mass? And of course, possibly the most puzzling inquiry of them all: Why does nature work the way it does?

Ferguson has been working on answering these questions for over 30 years, beginning with his graduate work at the University of California, Los Angeles (UCLA) in the early 1970s. This was an exciting time for particle physics research, as a particle called the charm quark had just been discovered at the Stanford Linear Accelerator Center, where Ferguson and some other UCLA researchers later performed experiments. The discovery of this quark added to the understanding of the fundamental pieces that make up matter. Through not directly involved, Ferguson was hooked on particle physics after witnessing the discovery.

“We’ve been at it now for about 30 years. We’ve made tremendous strides in understanding the properties of those particles, but we still don’t understand why nature did all of this. It’s a very complicated system,” Ferguson said.

The general goal of particle physics is to study the most fundamental particles that make up matter, and a particle accelerator is one of the most common tools used in reaching this goal. The European Organization for Nuclear Research explains that an accelerator’s general operation involves accelerating a particle, such as a proton or an electron, to speeds near the speed of light and causing a collision between it and another particle. The result is essentially a subatomic explosion that reveals all the smaller pieces that made up the two original particles. These pieces are observed by detectors and heavily studied. The most powerful particle accelerator in the world is located near Geneva, Switzerland. This is where Ferguson currently spends his summers.

This particle accelerator in Geneva is called the Large Hadron Collider (LHC), and it is roughly 17 miles in circumference, making it the largest particle accelerator in the world. Ferguson began working there over two decades ago, helping construct the Compact Muon Solenoid (CMS), a large detector that captures the products of a particle collision.

“Two protons hit each other and they can make lots of different things,” Ferguson said. “It turns out a lot of the interesting things that you’re looking at decay to muons.” The goals of the CMS are to discover particles that no one else has ever discovered and to measure particles that have already been discovered, but at a much higher level of detail. In working on the CMS, Ferguson is also accompanied by Carnegie Mellon physics professors James Russ, Manfred Paulini, and Helmut Vogel.

One particle, the Higgs boson, has been predicted to exist, but no one has been able to actually see or measure it yet — something that has kept particle physicists on their toes. It is the only particle described by the Standard Model that has not been confirmed through experimentation. The Standard Model is a theory that is useful to particle physicists, as it has predicted the existence of countless forces, particles, and interactions, thus gaining a reputation of being a theory of almost everything. The discovery of the Higgs boson would explain why certain things have mass, which would be an immense improvement in our understanding of the world around us.

“The Higgs is the last undiscovered particle in this beautiful theory. We want to complete it, and we want to make sure that the theory is as complete as can be,” Ferguson said.

The challenging part about discovering new particles is that physicists only know limited information about the particle. Fortunately, the Standard Model that predicts the Higgs boson’s existence gives physicists a few clues. It predicts that the Higgs boson can only exist under a certain range of energies, and this allows physicists to focus on this range when performing experiments. If the Higgs boson is never found and physicists have conclusive evidence that it does not exist, then the Standard Model will be flawed and the understanding of subatomic particles will be at stake.

“It would bring all of the physicists back to the drawing boards,” Ferguson said.

Although it would be exciting if the Higgs is discovered, Ferguson explains that experiments will not end there, as more questions will always and inevitably arise from new discoveries. “Each time you answer a question, you’ve got 10 more. It’s a continuing attempt to understand what’s around us. It’s a noble goal, and it’s fun.”