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|Atomic Number:||98||Atomic Symbol:||Cf|
|Atomic Weight:||251||Electron Configuration:||2-8-18-32-28-8-2|
|Melting Point:||oC||Boiling Point:||oC|
|Description:||Man made radioactive metal.|
History(State and University of California)
- Californium, the sixth transuranium element to be discovered, was produced
by Thompson, Street, Ghioirso, and Seaborg in 1950 by bombarding microgram
quantities of 242Cm with 35 MeV helium ions in the Berkeley 60-inch cyclotron.
- Californium (III) is the only ion stable in aqueous solutions, all attempts
to reduce or oxidize californium (III) having failed.
- The isotope 249Cf results from the beta decay of 249Bk while the heavier
isotopes are produced by intense neutron irradiation by the reactions.
- The existence of the isotopes 249Cf, 250Cf, 251Cf, and 252Cf makes it
feasible to isolate californium in weighable amounts so that its properties can
be investigated with macroscopic quantities.
- Californium-252 is a very strong neutron emitter. One microgram releases 170
million neutrons per minute, which presents biological hazards.
- Proper safeguards should be used in handling californium.
- Reduction of californium to its metallic state has not yet been
- Because californium is a very efficient source of neutrons, many new uses
are expected for it.
- It has already found use in neutron moisture gages and in well-logging (the
determination of water and oil-bearing layers).
- It is also being used as a portable neutron source for discovery of metals
such as gold or silver by on-the-spot activiation analysis.
- 252-Cf is now being offered for sale by the O.R.N.L. at a cost of $10/mg.
- As of May, 1975, more than 63 mg have been produced and sold.
- It has been suggested that californium may be produced in certain stellar
explosions, called supernovae, for the radioative decay of 254Cf (55-day
half-life) agrees with the characteristics of the light curves of such
explosions observed through telescopes. This suggestion, however, is questioned.