Research team creates antihelium-4

Kelly Tunney

Physics professors Declan Keane and Spiros Margetis were among a group of physicians who recently discovered and identified antihelium-4, the largest antinucleus.

The Department of Energy funded the roughly $60 million experiment, which used an accelerator at Brookhaven National Laboratory to smash gold nuclei together. This made millions of tiny particles, including antihelium-4, the antinucleus of helium, said Keane.

One of Keane’s former graduate students, Aihong Tang, developed a way to identify the antihelium particles they wanted to find.

“He came up with actually a very neat way to search very quickly through the half trillion fragments coming out of the collisions to find the ones that we were looking for very quickly,” Keane said.

Margetis said smashing the gold nuclei created the energy that was used to identify antimatter, the opposite of matter.

“When energy materializes, we know it materializes in exactly equal amounts of matter and anti-matter,” Margetis said. “So if you go from energy to matter and antimatter, you should have exactly equal amounts of both.”

The group used gold because it is the heaviest nuclei and produced the most particles, which gave them a better chance to get samples from, said Margetis.

“We make so many matter and anti-matter fundamental particles that there is a chance for two anti-protons and two anti-neutrons to come together and form an anti-helium nuclei,” he said.

However, antimatter is difficult to capture when materializing energy, even in lasers or strong magnetic fields, said Margetis.

“Anti-matter is very, very difficult to confine — very, very difficult to keep somewhere for a long time because the moment it touches something, it makes the opposite process,” he said. “Matter and antimatter make energy.”

Therefore, Margetis said the group had a very short amount of time to identify the antihydrogen-4 because it appeared and disappeared in about a millionth of a second.

Margetis said that the discovery will be the last of its kind for the foreseeable future.

“The next stable particle to be found… the next heavier and stable antimatter, the antilithium, needs so much data that it is impossible in our lifetimes to collect this amount of data,” Margetis said. “So essentially, we’ve closed the door with what is possible with current technology.”

Keane said the purpose of the experiment was to study the matter itself, rather than what it could be used for.

“The purpose is just to study matter at its most basic level; it’s not applied research,” he said. “We do these experiments involving colliding the nuclei at the accelerator lab just to learn about the structure of matter at it’s most fundamental level.”

Margertis said although there are other research teams out there also looking for the same antimatter material, his team came first.

“We came first in the publication, and that’s why it’s published in Nature, which is the highest publication, the highest impact journal,” Margetis said. “So we managed to beat them to the finish line.”

James Gleeson, chair of the physics department, said Kent State benefits from Margetis and Keane’s discovery.

“It helps the university, it helps our reputation, it helps us with the external funding agencies from the government; it’s just about every way you can think of,” Gleeson said. “It’s just a big plus for us.”

Contact Kelly Tunney at [email protected].