Californium is a radioactive transuranium element with high neutron emission rates.
Core Principles & Analysis
Californium was created at Berkeley in 1950 by bombarding curium-242 with alpha particles and was named after the state and the university where it was discovered.
Californium-252 (half-life 2.6 years) undergoes intense spontaneous fission, so microgram sources supply neutrons for reactor start-up, neutron radiography, and prospecting for metal ores.
At a quoted price around 27 million dollars per gram, californium is among the most expensive materials ever sold, yet it is one of the few transuranium elements with routine commercial uses.