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Material World
Element · Cf

Californium

A synthetic element that emits neutrons steadily enough to start reactors and find oil.

Radiation source

Californium-252 does something almost nothing else does conveniently: it splits spontaneously and releases neutrons, continuously, from a source small enough to hold. Neutrons are otherwise produced by accelerators or reactors, which are neither small nor portable.

A neutron source finds things a gamma source cannot. Neutrons interact strongly with hydrogen, so they reveal water, oil and organic material inside dense surroundings that X-rays pass straight through.

Uses

Well logging is the largest use: a californium source lowered down a borehole reveals the hydrogen content of the surrounding rock, which is how the presence of oil and water is inferred.

It is also used to start up nuclear reactors, where a known neutron source gives the instrumentation something to read before the chain reaction is self-sustaining, and in neutron radiography and the detection of explosives and landmines.

Medium confidence Weak evidence

How we know: checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source.

How this connects

Where a connection has been confirmed by an outside reference, that reference is named beside it.

is sourced from

is produced by

  • Neutron irradiation — process · produced in milligrams, as a portable neutron source for starting reactors and scanning for explosives

Sources

  • Material World
    Our own writing
  • Wikidata
    Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)
  • PubChem
    US National Library of Medicine · Mixed — aggregated third-party content, rights retained by depositors

Questions this page answers

Where it comes from, and what it becomes

Follow Californium back to what it starts as, and forward into what it becomes. Each step is a documented one — a real route material takes, not a chain of inference.

Upstream — what it comes from

  • Californium → is sourced from → Curium → is sourced from → Plutonium → is sourced from (formed from uranium-238 in a reactor and recovered from spent fuel) → Uranium → is produced by (as yellowcake rather than metal: leaching and solvent extraction end at a uranium oxide concentrate, and the metal is several conversion steps further on) → Solvent extraction and electrowinning → takes as input (in the low-grade and oxidised ores that flotation cannot economically treat, with bacteria oxidising the sulfide into a form the acid can attack) → Chalcopyrite
  • Californium → is produced by (produced in milligrams, as a portable neutron source for starting reactors and scanning for explosives) → Neutron irradiation → takes as input (uranium-238 is the feedstock for everything heavier: it absorbs neutrons without fissioning, which is what starts the sequence) → Uranium → is produced by (as yellowcake rather than metal: leaching and solvent extraction end at a uranium oxide concentrate, and the metal is several conversion steps further on) → Solvent extraction and electrowinning → takes as input (in the low-grade and oxidised ores that flotation cannot economically treat, with bacteria oxidising the sulfide into a form the acid can attack) → Chalcopyrite
  • Californium → is sourced from → Curium → is produced by (another step up again, and the point at which yields start falling away sharply) → Neutron irradiation → takes as input (uranium-238 is the feedstock for everything heavier: it absorbs neutrons without fissioning, which is what starts the sequence) → Uranium → is produced by (as yellowcake rather than metal: leaching and solvent extraction end at a uranium oxide concentrate, and the metal is several conversion steps further on) → Solvent extraction and electrowinning → takes as input (in the low-grade and oxidised ores that flotation cannot economically treat, with bacteria oxidising the sulfide into a form the acid can attack) → Chalcopyrite
  • Californium → is sourced from → Curium → is sourced from → Plutonium → is produced by (from uranium-238 absorbing a neutron and decaying twice — produced in every power reactor whether or not anybody wants it, and recovered only by reprocessing spent fuel) → Neutron irradiation → takes as input (uranium-238 is the feedstock for everything heavier: it absorbs neutrons without fissioning, which is what starts the sequence) → Uranium → is extracted from (the principal uranium ore, and the pitchblende the Curies worked) → Uraninite
  • Californium → is produced by (produced in milligrams, as a portable neutron source for starting reactors and scanning for explosives) → Neutron irradiation → takes as input (uranium-238 is the feedstock for everything heavier: it absorbs neutrons without fissioning, which is what starts the sequence) → Uranium → is extracted from (the principal uranium ore, and the pitchblende the Curies worked) → Uraninite
  • Californium → is sourced from → Curium → is sourced from → Plutonium → is sourced from (formed from uranium-238 in a reactor and recovered from spent fuel) → Uranium → is extracted from (the principal uranium ore, and the pitchblende the Curies worked) → Uraninite

These are the most distinct paths back. Californium can be traced through others besides.