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 of specialized applications as a strong neutron emitter, and each microgram of fresh californium produces 139 million neutrons per minute. This property makes californium useful as a neutron startup source for some nuclear reactors and as a portable (non-reactor based) neutron source for neutron activation analysis to detect trace amounts of elements in samples. Neutrons from californium are employed as a treatment of certain cervical and brain cancers where other radiation therapy is ineffective. It has been used in educational applications since 1969 when the Georgia Institute of Technology received a loan of 119 µg of californium-252 from the Savannah