UT Researchers Explore Fundamental Forces of Nature in Large Hadron Collider Experiments

With the world’s largest science project now smashing particles again after a two-year pause, UT researchers will play a role in experiments that could challenge the accepted understanding of the universe.


The ALICE detector at the Large Hadron Collider. Photo credit: CERN

The Large Hadron Collider at CERN (European Organization for Nuclear Research) in Geneva, Switzerland, is the world’s largest and most powerful particle accelerator. The collider received a two-year upgrade after it captured the world’s attention in 2012 with the discovery of the Higgs boson. The Higgs boson is an elementary particle that completes the Standard Model of particle physics. Its discovery allows scientists to further explore fundamental forces at work in nature.

UT students and faculty in physics and nuclear engineering, based on the Knoxville and the UT Space Institute campuses, are part of two teams developing electronics and hardware for the ALICE and CMS detectors, and monitoring and examining data collected in experiments.

At the Large Hadron Collider, superconducting electromagnets pull protons and heavy lead ions through ultrahigh vacuum tubes around a 17-mile underground track that straddles the French-Swiss border. The beams, running in opposite directions, collide particles at high energies and the points of collision are monitored through several detectors that encircle the beam pipe.

This upgraded LHC will have an increased energy of 13 teraelectronvolts, 60 percent higher than any accelerator has achieved before. The increased energy will provide a closer approximation of conditions following the Big Bang, and allow researchers to further examine the Higgs boson’s properties and investigate previously untestable theories of dark matter, micro black holes, supersymmetry, and extra dimensions.

UT’s involvement is a great opportunity for selected students – an intensive hands-on experience in an atmosphere of global collaboration.

“It’s a great experience for American students,” said Christine Nattrass, assistant professor of experimental nuclear physics at UT. “They will meet people from all over the world and make new friends, and be challenged to solve complex scientific and technical problems with researchers from all over the world.”

A Large Ion Collider Experiment (ALICE)

The ALICE research team studies matter as it existed immediately after the Big Bang.


Joel Mazer makes adjustments to ALICE detector electronics.

Soren Sorensen, professor of experimental nuclear physics and program manager for the USA ALICE collaboration, leads UT’s ALICE team. The team includes Nattrass and Ken Read, professor of experimental nuclear physics and UT/ORNL joint faculty member, along with graduate students Joel Mazer, Kyle Schmoll, Rebecca Scott, and Andy Castro; postdoctoral researchers Abhisek Sen and Natasha Sharma; and undergraduate student Meg Stuart.

The group studies “jets,” the shower of particles produced in high-energy collisions. Only the resulting hadrons are observable in the detector, so the researchers work backward to deduce what happened in the hot, dense pool of melted nuclear matter, called the quark-gluon-plasma, created with impact.

“When we study the quark-gluon-plasma, we are studying the strong force, which keeps nuclei together,” Nattrass said.

For Mazer, working on ALICE means hands-on learning in the world’s foremost experiment.

“I’ve been allowed to study the smallest and largest systems known. Performing at LHC, the largest, most energetic collider in the world, and being surrounded by some of the brightest minds in science from all around the globe is a very rewarding experience,” he said.

Compact Muon Solenoid (CMS)

The CMS detector is tasked with testing the Standard Model and looking for new physics.

UT’s CMS team, led by Professor Stefan Spanier, includes Keith Rose, postdoctoral researcher; and graduate students Grant Riley, Joe Heideman, Krishna Thapa, and Mark Foerster.


The CMS detector at the Large Hadron Collider. Photo credit: CERN

Rose and Riley led the effort to commission a new instrument added to the CMS detector for Run 2. Thapa and Foerster develop software and will be monitoring collision data from a computer lab in the Nielsen Physics building.

The CMS team is collaborating with the Space Institute’s laser group, led by physics Professor Lloyd Davis, and a group led by Eric Lukosi, assistant professor in UT’s nuclear engineering department, to find materials, like artificial diamonds, that can withstand the higher radiation loads that come with increases in beam intensity.

The CMS monitors the point where protons collide every 25 nanoseconds. Powerful computers filter data to find signals of undiscovered particles, sending the information worldwide to research sites, including the high-performance computing cluster at UT.

“We have hints of new particles, and their nature could be quite exciting—they could be additional Higgs particles that are not included in our present Standard Model,” said Spanier. “We may see new things no one has seen before. Hopefully, we’ll crack our present understanding of physics.”

For more about U.S. research at the Large Hadron Collider, visit http://uslhc.web.cern.ch.


Karen Dunlap (865-974-8674, kdunlap6@utk.edu)