Creating and confirming the heaviest elements on the periodic table is one of modern physics’ most complex challenges. These manufactured atoms, known as superheavy elements (SHEs), exist for only fractions of a second, making their direct observation impossible. Element 115, now officially named Moscovium (Mc), is a synthetic atom whose existence had to be proven through entirely indirect evidence. Scientists tracked the unique signature it left behind as it disintegrated, rather than “seeing” it directly. The verification process relied on a chain of highly specific, predictable nuclear events. This indirect method of proof, involving creating a single atom and tracking its demise, is the only way to establish the existence of these fleeting additions to the periodic table.
The Fusion Reaction Recipe
Scientists manufactured Element 115 using a precise nuclear reaction known as “hot fusion.” Researchers at the Joint Institute for Nuclear Research (JINR) in Russia, collaborating with American scientists, accelerated one atomic nucleus and smashed it into a dense target of another nucleus. The specific ingredients were a beam of Calcium-48 (\(^{48}\)Ca) ions and a target of Americium-243 (\(^{243}\)Am). Calcium-48 is a neutron-rich, stable isotope, which helps stabilize the resulting superheavy nucleus. The accelerated Calcium ions collided with the Americium target, overcoming the immense electrical repulsion between the two positively charged nuclei. This fusion created a highly energetic, unstable compound nucleus, which stabilized itself by ejecting a few neutrons to form the Moscovium isotope.
The Signature of Creation: Alpha Decay Chains
Confirmation of Element 115 came from its unique, predictable breakdown. Moscovium atoms are highly radioactive and predominantly decay through alpha emission, where the nucleus sheds an alpha particle. This process reduces the atomic number by two, transforming Moscovium (atomic number 115) into the lighter element Nihonium (atomic number 113). This new isotope is also unstable and undergoes its own alpha decay, transforming into yet another element. This sequential process creates a “decay chain” of distinct daughter elements that continues until a known, relatively long-lived isotope is reached. This chain is the unique fingerprint of the parent atom. Each step is characterized by two precise measurements: the specific energy of the emitted alpha particle and the exact time it takes for the decay to occur (the half-life of that isotope). Observing a complete sequence of these energy and time measurements that perfectly match theoretical predictions confirms the original atom was Moscovium.
Isolating the Atoms: Velocity Filters and Detection Systems
Detecting a single Moscovium atom requires specialized equipment to separate it from the overwhelming background noise of the experiment. The fusion reaction produces a massive amount of unreacted Calcium beam particles and other unwanted reaction products that must be filtered out. Scientists use powerful magnetic and electric devices known as recoil separators or velocity filters, such as the Dubna Gas-Filled Recoil Separator (DGFRS). These separators guide the newly formed superheavy atoms away from the intense stream of unreacted beam particles based on their velocity and mass-to-charge ratio. Only the slow-moving, heavy Moscovium atoms are directed to the detection array. The atoms are then implanted into position-sensitive silicon strip detectors. These detectors precisely record the time and exact location of the initial implantation event, signaling the creation of the Moscovium atom. The detector then waits for subsequent alpha decay events, recording the precise energy and timing of each alpha particle at the same location, capturing the entire decay chain signature.
Establishing Proof: Cross-Laboratory Verification
Observation of a decay chain in one laboratory is not sufficient for official discovery; independent confirmation by other major research facilities is required. Scientific consensus demands that the experiment be reproducible, ensuring the observed decay chains are not experimental artifacts. The initial findings from the Dubna-Livermore collaboration were rigorously reviewed by international scientific bodies, specifically the International Union of Pure and Applied Chemistry (IUPAC) and the International Union of Pure and Applied Physics (IUPAP). Independent experiments, such as those conducted at the GSI Helmholtz Centre for Heavy Ion Research in Germany, successfully replicated the specific energy and timing sequence of the Moscovium decay chains. Only after this cross-laboratory verification, which confirmed the unique nuclear fingerprint, did IUPAC formally recognize the discovery, solidifying Moscovium’s place in the periodic table.