Californium is a radioactive metallic chemical element with symbol Cf and atomic number 98. The element was first made in 1950 at the University of California Radiation Laboratory in Berkeley, 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).
Three reasons Californium stands out
- 1
Highly radioactive, used in metal detectors to identify gold and silver ores.
- 2
Difficult to produce and used only in small amounts.
- 3
It is used to start up nuclear reactors by providing an initial reliable source of neutrons.
A portable flood of neutrons
Californium-252 undergoes spontaneous fission often enough to act as an intense compact neutron source. It can start reactors, inspect materials, and help analyze ores. That usefulness comes with formidable shielding, security, scarcity, and cost: annual production is measured in very small amounts.