 Discovery Information
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| Who: G.T.Seaborg, S.G.Tompson, A. Ghiorso, K.Street Jr.
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| When: 1950 |
| Where: United States |
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| Name Origin
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| After the state and University of California. |
| "Californium" in different languages. |
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| Sources
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| Made by bombarding curium with helium ions.
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| Although californium does not occur naturally on Earth, the element and its decay products occur elsewhere in the universe.
Their electromagnetic emissions are regularly observed in the spectra of supernovae.
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| Uses
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| Californium is available only in very small quantities so its uses are limited, however, it is used in nuclear research as
a source of fission fragments. It is also useful as a neutron source for activation analysis to detect gold or silver. It can also be used in moisture gauges in oil wells.
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| History
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| Californium was first synthesized at the University of California, Berkeley by researchers Stanley G. Thompson, Kenneth Street,
Jr., Albert Ghiorso and G. T. Seaborg in 1950. It was the sixth transuranium element to be discovered and the team announced their discovery on March 17, 1950.
It was named after the U.S. state of California and for the University of California system.
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| To produce element 98, the team bombarded a microgram-sized target of 242Cm with 35 MeV alpha particles in the 60-inch Berkeley cyclotron which produced atoms of 245Cf (half-life 44 minutes) and a free neutron.
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| Notes
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| 252Cf (2.6 year half-life) is a very strong neutron emitter and is thus extremely radioactive and harmful (one microgram spontaneously emits 170 million neutrons per minute). The decay of 254Cf (55-day half-life) may have been detected through telescopes in supernovae remnants. 249Cf is formed from the beta decay of 249Bk and most other californium isotopes are made by subjecting berkelium to intense neutron radiation in a nuclear reactor.
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| Hazards
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| Californium is radioactive. |
