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
Californium 9, 1950. It was the sixth transuranium element to be discovered; the team announced its discovery on March 17, 1950. To produce californium, a microgram-sized target of curium-242 () was bombarded with 35 MeV-alpha particles () in the cyclotron at Berkeley, which produced californium-245 () plus one free neutron (). Only about 5,000 atoms of californium were produced in this experiment, and these atoms had a half-life of 44 minutes. The discoverers named the new element after the university and the state. This was a break from the convention used for elements 95 to 97, which drew inspiration from how