Scientists have achieved a breakthrough by producing super-heavy element 116 using a titanium-50 beam, marking a significant milestone towards potentially creating the heaviest element yet, element 120.
Researchers at the Department of Energy’s Lawrence Berkeley National Laboratory have been instrumental in identifying 16 of the 118 known elements. They have now accomplished a critical initial step that could lead to the creation of element 120.
Today, an international team of researchers, led by Berkeley Lab’s Heavy Element Group, announced the successful creation of superheavy element 116 using a titanium beam. This accomplishment, reported at the Nuclear Structure 2024 conference, signifies a pivotal advancement in the journey toward producing element 120. The findings will soon be published in the journal Physical Review Letters and made available on the arXiv online repository.
The team, after 22 days of operations at the 88-Inch Cyclotron, successfully generated two atoms of element 116, named livermorium. While creating element 120 would be an even more extraordinary feat due to its rarity, the team’s progress with element 116 provides a foundation for pursuing the creation of element 120 in the upcoming years.
Element 120, if synthesized, would become the heaviest known atom, positioned in the eighth row of the periodic table near the “island of stability.” This island refers to a theoretical cluster of superheavy elements with distinctive characteristics. Unlike previously discovered superheavy elements that quickly disintegrate, element 120, with the right balance of protons and neutrons, could exhibit enhanced stability, allowing for extended research opportunities. Exploring such extreme elements offers valuable insights into atomic behavior, validates nuclear physics models, and unveils the boundaries of atomic nuclei.
Making Superheavy Elements
The process of creating superheavy elements involves colliding two lighter elements to yield an atom with the desired number of protons. Although this concept seems straightforward in theory, the practical execution is exceedingly complex. The fusion of atoms can require an immense number of interactions, with limitations on the selection of elements suitable for use as a particle beam or target.
Scientists carefully choose specific isotopes for their beam and target, opting for variants of elements with matching proton counts but varying neutron numbers. The selection of suitable isotopes is crucial for the success of the experiment. For instance, to target element 120, researchers must utilize a beam composed of titanium atoms with 22 protons, as opposed to the conventional choice of calcium-48 with 20 protons.
The innovative approach adopted by the experts at the 88-Inch Cyclotron involved confirming the successful production of a high-intensity titanium-50 beam over an extended timeframe to synthesize element 116 – the heaviest element created at Berkeley Lab until now.
Previously, elements 114 to 118 had only been generated using a calcium-48 beam endowed with a special “magic” configuration conducive to fusing with target nuclei effectively. The successful creation of superheavy elements near the island of stability using a “non-magic” titanium-50 beam had been a subject of speculation within the scientific community.
The accomplishment of producing element 116 with a titanium beam showcases the effectiveness of this production method and establishes a pathway for pursuing the synthesis of element 120. These efforts align with the vision outlined in the Nuclear Science Advisory Committee’s 2023 Long-Range Plan for Nuclear Science.
Engineering Accomplishments
Generating an intense beam of titanium isotopes poses significant technical challenges. The intricate process commences with vaporizing a specialized titanium-50 isotope, a rare form constituting a small fraction of natural titanium, in a high-temperature oven. Subsequent steps involve ionization processes within VENUS, an advanced ion source featuring superconducting magnets designed to confine a plasma and manipulate charged titanium ions.
The production of high-current titanium beams necessitated meticulous planning to counteract potential stability issues arising from titanium’s reactivity with various gases. The team’s innovative inductive oven technology, sustaining a constant temperature for extended durations, ensures a steady output of titanium atoms directed towards the plasma within VENUS.
The carefully tuned titanium beam, comprising approximately 6 trillion ions per second, interacts with the target material (plutonium for element 116 and californium for element 120), leading to nuclear fusion. Precision control of the beam’s energy levels is crucial to facilitate successful fusion without inducing excessive disruption in the target nuclei.
Following the synthesis of the superheavy element, specialized detectors like SHREC (Super Heavy RECoil detector) in the Berkeley Gas-filled Separator are employed to capture vital data regarding energy release, particle location, and decay processes. These detectors play a pivotal role in verifying the creation of element 116 and its subsequent decay products.
Preparations to initiate the creation of element 120 are underway at the 88-Inch Cyclotron, including the configuration of a californium-249 target by collaborators at Oak Ridge National Laboratory. As the experimental setup matures, researchers anticipate commencing the ambitious endeavor, with potential commencement expected in 2025.
The quest to explore the boundaries of atomic structures and the periodic table remains a driving force for scientific inquiry. Despite the ephemeral nature of superheavy elements discovered to date, the pursuit of element 120 holds promise for advancing our understanding of nuclear physics and unraveling potential applications of these rare elements.
The collaboration for this groundbreaking research encompasses contributions from various institutions, including Berkeley Lab, Lund University, Argonne National Laboratory, Lawrence Livermore National Laboratory, San José State University, University of Strasbourg, University of Liverpool, Oregon State University, Texas A&M University, UC Berkeley, Oak Ridge National Laboratory, University of Manchester, ETH Zürich, and the Paul Scherrer Institute.
