After being successful in their attempt to synthesize the element with atomic number 116 (livermorium) using a titanium beam, scientists are ready to try to come up with a new element in the periodic table: element 120.
If discovered, the element with atomic number 120 would be the heaviest atom ever created, and would be in the eighth row of the periodic table. (The atomic number represents the number of protons in an atom; which, added to the number of neutrons, results in the mass of that atom.)
Researchers from the Heavy Elements Group at Lawrence Berkeley National Laboratory in the USA presented the results of the experiment at the Nuclear Structure 2024 conference. available on arXiv and was submitted to the journal Physical Review Letters.
The “discovery” of superheavy elements
It is the first time that scientists have managed to create atoms of a superheavy element — all those with an atomic number above 100 — using a beam of uranium. Even though the study uses the word “discovery”, superheavy elements do not exist in nature and can only be synthesized in the laboratory.
To create a superheavy element, scientists “clash” two lighter elements that combine to have the desired number of protons for the final atom. In other words, the combination of an element with atomic number 40 with one with atomic number 60 would result in an element with atomic number 100.
To be able to do this in practice, researchers usually use a calcium leach (which has 20 protons) to bombard another target element. This was the first time that a titanium beam (with 22 protons) was used — and successfully — in the manufacture of superheavy elements.
Titanium was chosen to form the new beam of atoms with a higher atomic number, as the target elements with an atomic number of 100 (fermium) or more are very unstable and have a very short half-life, which would make a successful experiment impossible.
Berkeley Lab scientists managed to make two atoms of livermorium, element 116, using a beam of titanium, over 22 days of operations in the lab’s heavy ion accelerator, the 88-Inch Cyclotron.
The search for a new element
Now that there is proof that the titanium beam works to synthesize superheavy elements, scientists want to create a new element for the periodic table, with 120 protons.
“When we try to make these incredibly rare elements, we are at the absolute limit of human knowledge and understanding, and there is no guarantee that physics will work the way we hope. Creating element 116 with titanium validates that this production method works, and we can now plan our search for element 120,” explained Jennifer Pore, a researcher in the Heavy Elements Group at Berkeley Lab.
To attempt to synthesize element 120, about 6 trillion titanium ions per second will need to hit the target element (californium), which is thinner than a piece of paper.
Additionally, operators of the laboratory’s heavy ion accelerator need to adjust the beam so that it has just the right amount of energy. If it is too little energy, the isotopes will not fuse into a heavy element, if it is too much, the titanium will explode the nuclei in the target element.
Researchers have not yet determined a date to begin trying to produce element 120 — once started, the attempt could take years to produce any atoms of the new element, if it happens.
“We have shown that we have a facility capable of doing this project, and that the physics appears to make it feasible,” said Reiner Kruecken, director of Berkeley Lab’s Nuclear Science Division. “Once we have our target, shielding and engineering controls in place, we will be ready to take on this challenging experiment.”
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