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 2.645 years. All the remaining isotopes have half-lives shorter than a year, and the majority of these have half-lives shorter than 20 minutes. The isotopes of californium range in mass number from 237 to 256. Californium-249 is formed from the beta decay of berkelium-249, and most other californium isotopes are made by subjecting berkelium to intense neutron radiation in a nuclear reactor. Although californium-251 has the longest half-life, its production yield is only 10% due to its tendency to collect neutrons (high neutron capture) and its tendency to interact with other particles (high neutron cross-section). Californium-252 is a very