New Elements
Research can have various forms of impact. Some discoveries shape the very nature of our existence. Others can be extremely important to the scientific community but barely make a ripple for the rest of society.
The research conducted by UT physicist Robert Grzywacz probably falls somewhere in between. His claim to fame is contributing to the discovery of four new elements recently added to the periodic table—atomic numbers 113, 115, 117, and 118.
Why is this such a big deal? Most people will probably never interact with a super-heavy element. But in the world of nuclear physics, the data acquisition technology developed by Grzywacz and his colleagues at Oak Ridge National Laboratory (ORNL) is a game changer.
“It’s a major shift in how other scientists will conduct experiments on super-heavy elements in order to understand how they were created in the first place,” explained Grzywacz, who is also the director of the UT-ORNL Joint Institute for Nuclear Physics and Applications.
From the beginning of his career, Grzywacz experimented with producing new isotopes—versions of an element with different mass—by measuring very short radioactive decays. “We successfully expanded the pool of isotopes by creating unusual combinations of protons and neutrons,” he said.
Unfortunately, the technology available at the time limited the amount and variety of data that could be collected. So Grzywacz and his ORNL colleagues decided to take the only logical course of action and develop a better data acquisition system. By employing a new type of digital signal processing, they could measure nuclear decays down to one millionth of a second.
The upgraded detector system uses a piece of silicon with horizontal and vertical strips that produce an electrical signal at the intersection when a beam hits the target. The problem with the old system was capturing enough information from the second signal after measuring the first one. Grzywacz solved the speed problem by taking a photographic signal of the whole pulse. That way any information that appears later can still be recorded.
Grzywacz compares the new technology to what happens when someone photobombs a picture you are trying to take. “When someone sticks their head in right before you take the picture, you see it,” he said. “We are trying to see the kind of intruders that are sticking their heads into the picture.”
The researchers are ultimately looking for several consecutive decays in the same location in order to identify a unique signature of the decay.
“We always thought this would be a great system to use for super-heavy element research because it’s reliable and capable of measuring fast decays,” Grzywacz said. “But it took a while to get fellow researchers on board.”
Together with his ORNL colleagues, Grzywacz worked directly with scientists from Russia and the United States who were responsible for the discovery and confirmation experiments of elements 115 and 117. The data acquisition system initially applied in the ORNL-based experiments was already used in studies searching for and detecting super-heavy nuclei in Russia and Germany.
“What we’re really trying to find out is if we make something new, what will cause it to survive,” Grzywacz said. “It’s really perfectly esoteric research from the point of having any kind of immediate application. This science is curiosity-driven.”
He noted that engaging in research out of curiosity is what helps lay the foundation for future discoveries. “I don’t know if even Mother Nature made these elements. Think about that. We’re creating samples of elements that we don’t know if they ever existed anywhere in the universe,” Grzywacz said.
Over the next thirty years, Grzywacz hopes someone will build on the technology to create more super-heavy elements. For now, he and his fellow nuclear physicists are studying the decay of fleeting nuclei that can explain nuclear reactions in stars. Maybe then we will be able to understand the chemical elements we are made of and how they were generated in the universe. Now that would make quite an impact.
By Amanda Womac
