Californium a nuclear explosion. Californium is not a major radionuclide at United States Department of Energy legacy sites since it was not produced in large quantities. Californium was once believed to be produced in supernovas, as their decay matches the 60-day half-life of Cf. However, subsequent studies failed to demonstrate any californium spectra, and supernova light curves are now thought to follow the decay of nickel-56. The transuranic elements from americium to fermium, including californium, occurred naturally in the natural nuclear fission reactor at Oklo, but no longer do so. Californium is produced in nuclear reactors and particle accelerators. Californium-250 is
Chemical element by symbol, as well as ionization energies of the elements. The nuclides of stable and radioactive elements are also available as a list of nuclides, sorted by length of half-life for those that are unstable. One of the most convenient, and certainly the most traditional presentation of the elements, is in the form of the periodic table, which groups together elements with similar chemical properties (and usually also similar electronic structures). The atomic number of an element is equal to the number of protons in each atom, and defines the element. For example, all carbon atoms contain 6 protons in