A New Way to Make Element 116 Opens the Door to Heavier Atoms

The recipe for making superheavy elements is simple in theory. You smash together two lighter elements that, combined, have the number of protons you want in your final atom. It's basic math: 1+2=3.

In practice, of course, it's incredibly difficult. It can take trillions of interactions before two atoms fuse successfully, and there are limitations on what elements can reasonably be turned into a particle beam or target.

Researchers select specific isotopes, variants of elements that have the same number of protons but a different number of neutrons, for their beam and target. The heaviest practical target is an isotope called californium-249, which has 98 protons. (A heavier target, such as one made of fermium with 100 protons, would decay too quickly). That means to attempt to make element 120, researchers cannot use their go-to beam of calcium-48 with its 20 protons. Instead, they need a beam of atoms with 22 protons: titanium, something that has not been commonly used in making superheavy elements.

Experts at the 88-Inch Cyclotron set out to verify that they could make a sufficiently intense beam of the isotope titanium-50 over a period of weeks and use it to make element 116, the heaviest element ever made at Berkeley Lab.

Until now, elements 114 to 118 had only ever been made with a calcium-48 beam, which has a special or "magic" configuration of neutrons and protons that helps it fuse with the target nuclei to produce superheavy elements. It had been an open question in the field whether it would even be possible to create superheavy elements near the island-of-stability using a "non-magic" beam such as titanium-50.

"It was an important first step to try to make something a little bit easier than a new element to see how going from a calcium beam to a titanium beam changes the rate at which we produce these elements," said Jennifer Pore, a scientist in Berkeley Lab's Heavy Element Group. "When we're trying to make these incredibly rare elements, we are standing at the absolute edge of human knowledge and understanding, and there is no guarantee that physics will work the way we expect. Creating element 116 with titanium validates that this method of production works and we can now plan our hunt for element 120."