Californium (Cf), element 98, is a synthetic, highly radioactive metal that is not found naturally on Earth. As a transuranium element, it exists only when artificially created in specialized laboratory settings. Its discovery is tied to the development of powerful particle accelerators following World War II, marking a significant moment in the expansion of the periodic table. The process of synthesizing this element defines the historical event of its official identification.
The Discovery Location
The successful creation of element 98 took place at the University of California Radiation Laboratory in Berkeley, California, now known as the Lawrence Berkeley National Laboratory. This facility was the center for heavy element research in the mid-20th century, establishing it as the only location equipped for such a technically demanding experiment. The primary research team responsible for the synthesis included Glenn T. Seaborg, Albert Ghiorso, Stanley G. Thompson, and Kenneth Street Jr.
The Necessary Apparatus
The experiment required a sophisticated instrument to initiate the nuclear reaction necessary for the element’s creation. The team utilized the laboratory’s 60-inch cyclotron, which is a type of particle accelerator designed to energize atomic particles. This device made the discovery possible by bombarding a miniscule target of curium-242 with high-speed alpha particles, which are the nuclei of helium atoms. This bombardment forced the particles to merge with the curium atoms, fundamentally changing the target element’s atomic structure. The nuclear reaction produced the isotope californium-245, along with a free neutron, but only in extremely small quantities, estimated to be fewer than a million atoms.
Naming the New Element
Following the successful synthesis, the discovery of the new element was formally announced in March 1950. The research team chose the name Californium to honor the state and the university where the scientific achievement occurred, mirroring the naming convention of the preceding element, berkelium. The initial identification of the minute amount of Californium-245 produced was confirmed through a process of chemical separation. Scientists used ion-exchange chromatography to isolate the new element from the target material and other byproducts. The final confirmation came from detecting the characteristic alpha decay signature of the newly formed californium atoms, which finalized its existence as element 98.