By UFO Weekly Staff [20240317]
Within modern nuclear physics, the quest to create and study superheavy elements (SHEs) stands out as one of the most challenging and awe-inspiring pursuits. These are elements that surpass atomic number 104 (rutherfordium) on the periodic table, often extending all the way to the edge of, and perhaps beyond, the so-called “island of stability.” While elements up to 118 (oganesson) have been confirmed, scientists around the globe have set their sights on synthesizing elements 119 and 120. These two represent the next milestone in a continuing journey that stretches the limits of how atomic nuclei can form and persist—if only for fleeting instants. In this first installment of a three-part series, we will introduce the broader context of superheavy element research, explain why making such short-lived atoms is so formidable, and delve into the first of several major technical advances helping researchers push beyond the known frontier: the upgrade of superheavy element “factories.”
The Significance of Superheavy Elements
To appreciate the importance of pursuing new superheavy elements, one must first understand the concept of nuclear stability. Each element’s identity on the periodic table is defined by its atomic number, Z, which counts the number of protons in the nucleus. As Z increases, the repulsive force between positively charged protons grows, making it increasingly difficult for the nucleus to remain bound. Neutrons help offset this repulsion by providing an additional attractive nuclear force, but there is a practical limit to how many neutrons can be packed in before the nucleus becomes unstable. Past a certain point, nuclei decay very rapidly—sometimes in mere microseconds or less—making their creation and detection a monumental technical feat.
Since the mid-20th century, physicists and chemists have used high-powered particle accelerators to shoot ion beams at target materials in hopes of fusing them into heavier atoms. Initially, these efforts led to the discovery of transuranium elements such as plutonium (Z=94) and curium (Z=96). Over time, a variety of sophisticated accelerators were constructed around the world—at institutions like the Lawrence Berkeley National Laboratory (LBNL) in the United States, the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, and RIKEN in Japan—to reach atomic numbers beyond 100. Each success extended the known periodic table: rutherfordium (Z=104), dubnium (Z=105), seaborgium (Z=106), and so on. Yet the higher scientists went, the more difficult it became to piece together the next heaviest nucleus.
While many superheavy elements are ephemeral, decaying almost as soon as they form, there is a compelling theoretical rationale that predicts an “island of stability”—a region in which superheavy nuclei might have comparably longer half-lives (seconds, hours, or even longer). Discovering precisely where this island lies, or how close we can get to it, has profound implications for our fundamental understanding of nuclear forces, shell structure, and the limits of matter itself. Element 120 is often cited as a crucial stepping stone toward this possible island of stability. Even if no such stable isotopes exist, the chase reveals new physics in the borderline territory between bound and unbound nuclei.
Challenges in Synthesizing Superheavy Elements
Synthesizing superheavy elements is profoundly difficult for multiple reasons. First, the probability of any two nuclei fusing under accelerator conditions is extremely low. In nuclear terminology, this probability is represented by a cross section, measured in units called barns. For the heaviest elements, cross sections can fall to mere femtobarns (10⁻³⁰ cm²) or even smaller. This effectively means that out of trillions upon trillions of collision attempts, only a minuscule fraction culminate in the formation of a single, short-lived superheavy nucleus.
Second, even once the nucleus forms, it is often highly excited and must shed excess energy—typically by emitting neutrons—before it settles into a ground or near-ground state. Only then can it exist long enough to be detected. Many attempts at synthesizing heavier elements fail if the newly formed compound nucleus fissions apart or otherwise decays too rapidly. The entire process is like coaxing two intricately choreographed dancers to join in a fleeting step, only for them to spin apart almost instantly.
Third, detection demands extraordinary precision. Experimental teams build elaborate systems of recoil separators that filter out the beam particles and reaction byproducts, leaving only the newly fused nucleus on a path to detectors. The detectors themselves are arranged to record alpha decays, spontaneous fission events, or other decay signatures that confirm the identity of the newly formed isotope. Since these signals can be overwhelmed by background noise, complex electronics and software are needed to distinguish real events from false positives.
Finally, every aspect must be optimized: the choice of projectile (often a relatively light ion like calcium-48 or titanium-50), the composition and thickness of the target, the energy of the beam, and the detection apparatus. Each parameter can be the difference between a few fleeting signals and complete null results. A major reason these experiments can run for months or even years is that scientists must accumulate enough beam time to capture just a small handful of potential superheavy nuclei. All these factors underscore the elaborate interplay of physics and engineering that stands behind any new superheavy element claim.
The Emergence of “Factory” Upgrades
To push further in synthesizing elements beyond oganesson (element 118), numerous research facilities have retooled or expanded in what can be called a new generation of superheavy element “factories.” This is a key factor shaping the current race toward element 120. Among these upgrades, the Joint Institute for Nuclear Research (JINR) in Dubna stands out with its Superheavy Element Factory (SHE Factory). This major infrastructure project was designed to yield higher beam intensities for extended durations, thus boosting the probability that at least a few successful fusion events might be observed.
Under older accelerator configurations, it was challenging to hold ion beams at sustained high intensities because the target would rapidly degrade or the system would overheat, limiting the effective beam current. By introducing enhanced cooling systems, newly engineered target stations, and refined ion optics, the SHE Factory can maintain heavier-ion beams for longer. As the cross sections for synthesizing unknown superheavies can be vanishingly small, these persistent beams offer a better chance of registering successful events.
At GSI in Darmstadt, plans tied to the upcoming Facility for Antiproton and Ion Research (FAIR) will provide new avenues for heavy-ion collisions, though the search for superheavy elements is only part of FAIR’s broader research scope. Still, the infusion of technology—upgraded superconducting magnets, advanced vacuum systems, improved data acquisition—will trickle into the SHE domain. Even small improvements in beam intensity or target stability can shift the odds in favor of observing an event that might otherwise go unnoticed.
Additionally, Lawrence Berkeley National Laboratory has been optimizing systems at its 88-Inch Cyclotron. Past experiments at LBNL contributed to the discoveries of elements such as seaborgium (Z=106). Although the lab’s current focus is more diffuse, the rising tide of accelerator technology still benefits many nuclear physics subfields, including superheavy element synthesis. As an illustration, improved magnet design and digital control of beam energies increase experiment precision, ensuring the best match of projectile velocity to target-nucleus fusion windows.
The Multifaceted Nature of Factory Upgrades
One might assume that “factory upgrades” simply mean building a bigger, more powerful accelerator. However, in superheavy element research, the term encompasses a suite of changes that collectively raise the probability of success. These changes include:
- Intense, High-Quality Ion Beams
Beams must deliver a consistent stream of ions at carefully tuned energies. Instability in the beam can compromise fusion attempts. Facilities have worked to refine electron cyclotron resonance (ECR) ion sources to achieve more stable currents of isotopes like calcium-48, which has proven crucial in synthesizing elements 114 through 118. Future work may involve heavier projectiles with carefully managed intensities. - Improved Target Handling and Replacement
Targets undergo significant wear from prolonged ion bombardment. To mitigate this, labs have implemented rotating target wheels or advanced cooling to spread the thermal load. This approach prolongs target life, allowing longer runs and higher integrated beam dose—essential for rare-event detection. Many “factory” setups also streamline the replacement or refurbishment of targets, minimizing downtime. - Sophisticated Vacuum and Beam Focusing Systems
Higher beam currents can lead to an increased likelihood of contaminants, scattering, or other undesired interactions that clutter data. Factories must have top-tier vacuum systems and advanced ion-optical elements (like quadruple or sextuple magnets) to maintain beam purity. By precisely focusing and steering the beam, the chance of hitting the target in the intended energy window goes up, again enhancing the odds of successful fusion. - Resilient Infrastructure for Long Campaigns
Because experiments might run continuously for months, the entire facility—from power supplies and cooling towers to data acquisition racks—must remain stable under heavy operational loads. “Factory” expansions typically include robust backup systems, advanced environmental controls, and well-planned maintenance schedules to avoid catastrophic outages mid-campaign.
Collectively, these upgrades reflect a shift from sporadic, small-scale attempts to a more industrial-scale pursuit of superheavy elements. Instead of short experiments trying different beams and targets, labs now design multi-year strategies to incrementally optimize the conditions for forging new elements. The goal is to reach a production rate of a few atoms per week or even a few atoms per day for heavier isotopes, which, while seeming incredibly low, can be game-changing in a field where the baseline might otherwise be a few atoms per year.
The Road Ahead for Element 120
With element 118 (oganesson) already synthesized, the next formidable leap involves bridging the gap between known territory and the hypothesized region of heavier nuclei. The most often discussed path is a fusion reaction between a relatively heavy projectile (like titanium-50 or chromium-54) and a suitably neutron-rich actinide target, perhaps berkelium or californium. The synergy between carefully chosen reactants and upgraded SHE factories is expected to crack open new territory. Yet whether these heavier nuclei will exhibit a fleeting lifespan or reveal somewhat longer half-lives remains unknown until experiments verify theoretical predictions.
Scientists anticipate that for each incremental advance in atomic number, the cross sections could drop even further. To sustain the possibility of detecting just one or two decay chains from a new element, the beams must run continuously for weeks or months. During that time, the cross section might be so small that conventional detection methods come under tremendous strain, pushing researchers to constantly refine the signal-to-noise ratio.
Even if experiments definitively produce atoms of element 120, researchers must confirm the result. That confirmation usually hinges on alpha-decay chains that link back to known isotopes. If element 120’s primary decay mode or half-life does not neatly match theoretical projections, analyzing each alpha or spontaneous fission event could be an intricate puzzle. The successful detection would involve a chain: element 120 decays to a daughter, which decays further, each with unique alpha energies (and possibly gamma-ray signatures). The final known nucleus in the chain serves as the fingerprint that confirms the entire lineage. It is akin to forensic evidence in nuclear science: only when the chain lines up with recognized isotopes do scientists confidently declare a new element discovered.
Conclusion and Preview
In this first part of our three-part exploration, we have introduced the context that drives the search for superheavy elements, especially as scientists aim to reach or surpass element 120. From the historical evolution of transuranium research to the extraordinary challenges inherent in forging atomic nuclei with extremely high proton counts, the field’s complexity is evident. The impetus for these herculean efforts lies in fundamental questions about nuclear stability, the architecture of matter, and the intriguing possibility of an island of stability further up the periodic table.
Central to the growing optimism is a new generation of superheavy element “factories.” By enlarging and optimizing beam power, improving target materials, and enhancing the surrounding infrastructure, scientists have created specialized environments where forging heavier atoms is no longer a miracle—it is a carefully orchestrated campaign that, while still improbable, has become measurably more feasible.
In the second installment of this series, we will delve deeper into the next steps scientists are taking. This will include a look at improved beam technology and ion sources, which allow for more precise and intense beams, as well as advanced target design. Each development holds a piece of the larger puzzle, enabling researchers worldwide to collaborate in an unprecedented push toward discovering the next chart-topping elements on the periodic table.