A Universe in Each Crystal
Andrew Marotta was captivated by nuclear engineering during his 10th grade environmental energy class.
“The idea of fusion and nuclear energy production really got me interested,” he recalled. “I thought, ‘I want to be a part of this new age of energy production.’”
Drawn to the University of Tennessee by its strong Department of Nuclear Engineering (NE) and proximity to historical Oak Ridge—as well as the promise of warmer winters than he was used to in New York—Marotta became a Vol in the fall of 2024.
One year later, he is preparing to return not only to campus but to the laboratory.
Scant weeks after he first arrived on campus, Marotta’s physics professor told the class about the many opportunities for undergraduate students to conduct research at UT.
“I thought, ‘I’ll put myself out there and see what happens,’” Marotta said. “‘If a professor connects with me, then that’s great; if no one can take me on, I’ll continue to focus on what I’m doing.’ I felt like I had no way to lose.”
After a discussion of his goals with David Keffer, a professor in the Department of Materials Science and Engineering (MSE), Marotta reached out to NE Research Assistant Professor Luis Stand to ask about opportunities researching scintillators, which are crystalline materials that generate visual light in response to radioactive particles.
As Stand took him on a lab tour through the Scintillation Materials Research Center (SMRC), Marotta felt the same tug he had experienced in 10th grade.
“It just looked so cool,” he said. “I knew I had to do work there.”
Experiencing the Scientific Process
Marotta spent his first month at the SMRC conducting safety training and learning standard operating procedures for the lab equipment, some of which is extremely delicate. All the while, Stand made sure Marotta understood what each instrument tested and why.
“Luis was a very helpful mentor,” said Marotta. “We talked about the specific mechanism of the crystal I was going to study, and then he explained how each measurement was helping to map out that mechanism.”
Under the advisement of Stand, SMRC Director Chuck Melcher, and MSE Associate Professor Mariya Zhuravleva, Marotta embarked on his own research project to systematically characterize a particular type of scintillator.
Sodium-doped (containing) cesium iodide (CsI:Na) scintillators are used for radiation detection in many fields, including physics, medicine, and even geology. However, the crystals exhibit extended afterglow, meaning that they continue producing visible light after a radioactive signal has stopped. This can reduce their effectiveness in very sensitive applications like medical diagnostics.
Marotta was tasked with characterizing the properties of CsI:Na crystals that had been made to include various other elements that the team hoped would reduce the afterglow.
“Once I was fully trained, Luis was pretty hands-free when I was actually taking the measurements,” Marotta said. “Obviously he was always there in case something went wrong, but he let me experience the scientific process for myself.”
Marotta particularly enjoyed taking samples’ radioluminescence spectra, or the specific wavelengths of light that each crystal emits.
“Once I had set up my sample, like, an inch away from the reader, and it didn’t work at all. Then Luis came over and moved it about an inch, and the reading changed entirely,” Marotta recounted. “I thought it was so crazy how every little difference matters so dramatically, even though you’re working with something so tiny. It’s like there’s a whole universe inside each little crystal.”
Expanding Career Options
Marotta found that every tested cation reduced afterglow in the CsI:Na scintillators, with strontium (Sr) having the most promise. He presented his results at UT’s 2025 Exhibition of Undergraduate Research and Creative Achievement (EURēCA).
He also discovered a deep and unexpected love for laboratory work.
“Originally, when I decided to go into nuclear engineering, my thinking was that I wanted to work in energy generation,” he reflected, “but now I’m more interested in radiology. I had also never thought I’d go into a research-oriented job, but now I would 100 percent consider it.”
Over the summer, Marotta has been reading up on scintillator mechanics in preparation for another year of research at the SMRC. He hopes to work with different types of scintillators and conduct research in multiple labs.
“I want to expand my experience and get a feel for different aspects of this research,” he said. “I think a lot of people get dead set on what they want to do before they actually try it out, but this project has shown me that it’s definitely important to try something first, to see what it is really like.”
Contact
Izzie Gall (865-974-7203, egall4@utk.edu)