Two atoms of element 116 demonstrate path to hunt for element 120 and extend the periodic table

Jacklyn Gates leads superheavy element research at Lawrence Berkeley National Laboratory.

BERKELEY, CALIFORNIA—At 2:47 p.m. on 27 April, a computer connected to an atom smasher here at Lawrence Berkeley National Laboratory (LBNL) registered a single blip, followed almost immediately by three more. An automated Slack message of a “thinking” face emoji pinged its way to Jacklyn Gates, head of LBNL’s superheavy element team, who soon discovered that the blips—signals spit out after atoms crashed into the bull’s eye of a detector—represented evidence for an atom of element 116 followed by its decay into daughter products. In 2000, scientists in Russia first created element 116, the third heaviest atom known in nature, by smashing a beam of calcium atoms into a target made of curium. But LBNL used a beam of titanium atoms and a plutonium target, a rival approach that sets the stage for the lab to hunt for element 120, which would be the heaviest element ever created...

...From 1936 through 1976, LBNL used its atom smashers to discover 16 elements, from element 43 (technetium) to 106 (seaborgium). But in the decades that followed the axis of superheavy research shifted to facilities in Germany, Japan, and Russia, which collectively discovered the last 12 elements...

...In principle, synthesizing superheavy elements is simple. Researchers fire beams of ions of a lighter element into a thin target of a heavier element and hope the two nuclei fuse. The most recent superheavies, 114 through 118, were discovered using a beam of calcium-48, whose “magic” number of protons and neutrons lend it stability and a higher probability of merging with target nuclei. But that approach concluded with calcium ions fusing with californium to produce element 118, because elements heavier than californium cannot be made in large enough quantities for viable targets. So, physicists began firing beams of heavier but less stable ions, such as titanium and chromium...

...LBNL’s new titanium beam is more powerful, generating some 6 trillion ions per second. It begins with a ceramic oven the size of a peanut that vaporizes titanium at temperatures of 1800°C. The atoms are confined by superconducting magnets that must be cooled to near absolute zero. Microwaves strip away about half of each atom’s electrons, creating ions that are injected into a cyclotron that accelerates them to 11% the speed of light. They are then fired at a plutonium disk, which spins 30 times per second to help dissipate the heat of the collisions...