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ND physicists help with ‘Big Bang’ experiment

Jenn Metz | Thursday, September 11, 2008

Notre Dame particle physicists are participating in an experiment almost 20 years in the making designed to uncover the mysteries of the universe moments after its creation.

The experiment, which uses a particle accelerator called the Large Hadron Collider (LHC), launched Wednesday in Geneva, Switzerland.

The Notre Dame team, part of a larger contingent of American physicists and scientists from many countries around the world, at the forefront of the field of particle physics, has been working on the project since its inception in 1993, Associate Professor of Physics Colin Jessop said.

“We’ve been a part of this community for many, many years,” he said.

Six faculty members are involved in the project: Professors Randy Ruchti, Michael Hildreth, Mitchell Wayne, Kevin Lannon, Dan Karmgard, along with Jessop.

Two post-doctoral researchers, Jeff Kolb and Nancy Marinelli, are currently at the European Organization for Nuclear Research, better known by its French acronym, CERN, in Switzerland, the operation center for the LHC.

The LHC collides protons – subatomic particles – together at extremely high energies. The $10 billion machine is located about 300 feet beneath the ground on the French-Swiss border and spans a circumference of 17 miles.

A ring of superconducting magnets accelerates the particles to extremely high energies, “almost to the speed of light,” Jessop said.

As the particles circulate around the ring, they gain more and more energy until they are smashed together, he said.

Large detectors, “sort of like a giant digital camera,” which were in part designed by the Notre Dame team, will be there when the collisions happen to collect data, Jessop said.

These machines detect all the particles that are created in the collisions, which will replicate the particles in existence about one microsecond after the Big Bang 13.7 billion years ago.

This, Jessop said, is extremely important.

“We are the remnants of the Big Bang,” he said.

The data will help in “understanding the interactions of the particles at the early stages of the universe that have determined how the universe is today,” he said.

Three Notre Dame graduate students – Ted Kolberg, Jamie Antonelli and Sean Lynch – are currently in Switzerland collecting data and helping to operate the detectors. They will remain at the experiment site for one or two years before returning to Notre Dame and finishing their degrees.

The Notre Dame team worked on the detectors in all phases – including “commissioning the detector, making it work, and running it,” Jessop said.

When the switch was first turned on Wednesday at 1:30 a.m., it was “our time,” Jessop said. “We put the first beam [into the accelerator] … It was a seminal moment for us.”

A principle goal of the experiment is to discover the existence of the Higgs boson particle – “a key to understanding our theories of the universe,” Jessop said.

Physicists have been looking for this particle – deemed “The Holy Grail of particle physics” – for 42 years. Its discovery will help answer the question of what is mass.

Mass is property of objects in the universe. The Higgs boson particle, named after Scottish physicist Peter Higgs, is that which gives every particle mass, Jessop explained. Without this particle, scientists do not understand why there is mass in the universe.

“This is crucial to our theories of explaining the properties we have. It is a key constituent in understanding why every other particle has mass,” he said.

The experiment will probably last for 20 years, Jessop said. During the project the machines involved will constantly improve.

“It’s very exciting. It’s taken us 20 years to get here, and we expect to make amazing discoveries to elucidate problems about how the universe is right now,” he said.

Notre Dame physicists – graduate and undergraduate – will be analyzing the data from the experiment for the next 20 years.

Graduate students have already begun looking at the data, and will continue to do so for the entirety of their Ph.D programs, Jessop said.

The data will be available to undergraduate physics majors, who possess the technical knowledge to comprehend it, in the next several months. The results of the experiment will be taught to general science classes at the University.

Notre Dame is involved in an outreach program called QuarkNet – named after the particle called a “quark,” the most fundamental of all particles that everything is built of – which allows high school teachers and students to do research at Notre Dame. The results of the LHC experiment will be shared through this program, “bringing the results to younger students as well,” Jessop said.