Californium Californium Californium is a radioactive chemical element with symbol Cf and atomic number 98. The element was first synthesized in 1950 at the Lawrence Berkeley National Laboratory (then the University of California Radiation Laboratory), by bombarding curium with alpha particles (helium-4 ions). It is an actinide element, the sixth transuranium element to be synthesized, and has the second-highest atomic mass of all the elements that have been produced in amounts large enough to see with the unaided eye (after einsteinium). The element was named after the university and the state of California. Two crystalline forms exist for californium under normal
Californium of use, reactor start-up (48.3%), fuel rod scanning (25.3%), and activation analysis (19.4%). By 1994 most californium-252 was used in neutron radiography (77.4%), with fuel rod scanning (12.1%) and reactor start-up (6.9%) as important but distant secondary uses. Californium-251 has a very small calculated critical mass of about , high lethality, and a relatively short period of toxic environmental irradiation. The low critical mass of californium led to some exaggerated claims about possible uses for the element. In October 2006, researchers announced that three atoms of oganesson (element 118) had been identified at the Joint Institute for Nuclear Research in