In a remarkable feat of modern-day alchemy, scientists have used a beam of vaporized titanium to create one of Earth's heaviest elements. This innovative method could potentially lead to the discovery of even heavier elements in the future.
For the first time, researchers have successfully used this new technique to produce a superheavy element, livermorium. The process involved heating a sample of the rare isotope titanium-50 to nearly 1650 °C (3000 °F), releasing ions that were then directed at another element.
Livermorium was first synthesized in 2000 and isn't the heaviest element humans have created (that title belongs to oganesson, with atomic number 118). However, the recent production of a few atoms of livermorium at the Lawrence Berkeley National Laboratory signifies more than just a periodic table update.
Using a titanium beam to create livermorium is a test run for the scientists' ultimate goal: creating unbinilium, which would have 120 protons, making it the heaviest element ever produced.
"This reaction had never been demonstrated before, and it was essential to prove it was possible before embarking on our attempt to make 120," said Jacklyn Gates, the nuclear chemist at Berkeley Lab who led the research.
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Calcium-48, with its 20 protons, has traditionally been the preferred beam due to its 'magic number' of protons and neutrons, which makes it more stable and easier to fuse with targets. Titanium-50, while not 'magic,' has 22 protons, which are needed for achieving heavier atomic weights without the beam disintegrating.
"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," explained Jennifer Pore, a physicist at Berkeley Lab.
"Creating element 116 with titanium validates that this method of production works, and we can now plan our hunt for element 120."
The team operated Berkeley Lab's 88-inch cyclotron for 22 days, accelerating titanium ions into a powerful beam that fused with the target, ultimately producing just two atoms of livermorium.
Creating unbinilium using this method, by targeting californium-249, will be faster than previous approaches, but it will still be a lengthy process.
"We think it will take about 10 times longer to make 120 than 116," said Reiner Kruecken, a nuclear physicist at Berkeley Lab.
This development marks a return to the superheavy element race for Berkeley Lab, a pioneer in elemental discovery in the 20th century.
Scientists globally have been competing to produce unbinilium since at least 2006, when a Russian team at the Joint Institute for Nuclear Research made the first attempt. Despite several attempts by researchers at Germany's GSI Helmholtz Centre for Heavy Ion Research between 2007 and 2012, success remained elusive.
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| Researchers want to fuse isotopes of titanium and californium to make element 120. (Jenny Nuss/Berkeley Lab) |
Now, with researchers from the US, China, and Russia all in the race, the future applications of such discoveries are eagerly anticipated.
"It's really important that the US is back in this race because superheavy elements are very important scientifically," nuclear physicist Witold Nazarewicz, who was not involved in the research, told Robert Service at Science.
Element 120 is near the theoretical 'island of stability,' a region where superheavy elements are predicted to have much longer half-lives due to their 'magic numbers' of protons and neutrons.
These stable, long-lived superheavy elements could provide scientists with valuable opportunities to study extreme atomic behaviors, test nuclear physics models, and explore the limits of atomic nuclei.
Sources:
Submitted on 22 Jul 2024 to Physical Review Letters, and is available as a preprint at arXiv.
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