Californium-252, produced during the later experiments, has a half life of around two and a half years. During much of that time, a microgram-sized sample is giving off 170,000,000 neutrons per ...

Californium, whose atomic number is 98 and symbol is Cf, is a radioactive metallic element and the heaviest element to occur naturally on Earth. Heavier elements can only be produced in a lab.

Californium, or Cf, is a radioactive metallic element. It was first made at the University of California, Berkeley, in 1950 when scientists bonded curium with alpha particles.