Since 1993, the International Atomic Energy Agency has tracked 2,500 trafficking cases of nuclear material. While there has yet to be a detonation of a dirty bomb, the threat remains present. In the unlikely event of a nuclear attack on American soil, Antonio Simonetti, associate professor of civil & environmental engineering & earth sciences, makes one thing clear: The perpetrator could and would be found.

Simonetti is a geochemist who specializes in characterizing the chemical and isotopic composition of materials. Traditionally, that involves studying rocks and minerals, which Simonetti did for many years. In 2011 he pivoted to assess nuclear materials like trinitite at the request of National Nuclear Security Agency. In that role, he used laser ablation-inductively coupled plasma mass spectrometry (ICP-MS) to study blast melt from the first atomic bomb test in New Mexico in 1945 and precisely identified where remnants of plutonium fuel resided after the explosion.

“It’s helpful because we then know where to look if a similar situation were to occur,” he says.

Now he’s funded by a $1.75 million grant from the Domestic Nuclear Detection Office at the Department of Homeland Security. The five-year project titled “Advancement of Nuclear Forensic Science” specifically seeks to characterize radioactive materials to link them to their sources and improve detection techniques. With a wider lens, the work is serving as a deterrent to nuclear proliferation and acts of terrorism.

“Right now what we’re doing is characterizing the raw materials and looking at uraninite deposits worldwide. If a country is interested in developing a nuclear arsenal, they need uranium. That’s where it all starts,” Simonetti says.

Uranium and other nuclear materials vary slightly depending on their origin, he explains. Uranium from Kazakhstan will have a different chemical signature than uranium from Australia or Russia or the United States. Simonetti also notes that even once uranium is altered to make yellow cake, fuel pellets or other explosive material, its chemical composition doesn’t change. So if you can understand the material in a pre-detonated state, it would hold true if seized from a trafficker or even after an explosion. Using his database of the variations of uranium, partners at Los Alamos National Lab and the Department of Homeland Security could quickly identify the original source and manufacturing details and then track down the culprit.

Speed is key. While there have long been ways to trace these materials, traditional methods can take several weeks, which is too long when decisions about national security are urgent. But Simonetti’s lab can get the information in mere hours by using state-of-the-art laser technology and ICP-MS instrumentation. And he’s looking for even faster methods.

“Not only can we get the information to [Los Alamos] fast, we can also help them develop new avenues of identifying research on forensic signatures,” he says.

Simonetti says the opportunity for creativity and exploration is why Notre Dame, as a university, is an essential partner. Universities aren’t tied down to a strict daily routine like national labs, so they can brainstorm and investigate new options. His work can also remain unclassified unlike the national labs. That’s important, he says, because if the public, especially those interested in causing harm, know they can be traced, they may think twice before using or trafficking nuclear materials.

“If we can deter dirty bombs on a small scale, we’re serving a great purpose,” Simonetti says.

Maloney Foster is a Notre Dame senior and Naval ROTC midshipman. He works in Simonetti’s lab and has seen firsthand how the work contributes to national security.

“If you really try to sum up and generalize what Professor Simonetti’s research does, it makes the country safer. It makes us more aware of where possible threats can be coming from,” Foster says. “In general, it ensures we have strong security with making sure everything that comes in and out of the country is legal and safe. And it helps us know what forces, abroad or domestic, have dangerous materials.”

As Foster prepares to commission into the Navy, he says his experience in Simonetti’s lab gave him valuable experience as both a student and a midshipman.

“I felt that getting involved in Professor Simonetti’s research was a good way for me to get exposure to the nuclear world on the national security side but also the engineering and science side, because that’s more of the side I’d be concerned with during my time in the Navy.”

While Foster and peers are getting hands-on experience, Simonetti is enthusiastic about training the next generation of nuclear forensic scientists to make sure the work continues and improves.

“The research we’re doing now is never going to go away,” he says. “The perfect, end result would be the characterization of the raw materials that we’re doing for example right now. Those ratios will never change. Those signatures won’t change. Whether the materials are intercepted tomorrow, ten years from now or 20 years from now, our research will always be valid. There will always be this need for our database. The way we can help further is, can we analyze other elements? Or are there different aspects of the samples we should be looking at?”

Simonetti’s group has made great progress in fingerprinting uranium samples. Meanwhile, Notre Dame colleague Amy Hixon has also begun assessing how time, water and air can affect isotopic signatures of uranium ores. Now halfway through his five-year partnership with the Department of Homeland Security, Simonetti’s enthusiasm for the project remains unyielding.

“Every solid piece of material has a story to tell. The science has always intrigued me. I’ve been doing it for 25 years now and it’s not going to go away,” he says. “I love that we’re doing something useful for the country.”