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Californium-252 production diagram. Californium-252 (Cf-252, 252 Cf) undergoes spontaneous fission with a branching ratio of 3.09% and is used in small neutron sources. Fission neutrons have an energy range of 0 to 13 MeV with a mean value of 2.3 MeV and a most probable value of 1 MeV. [11]
252 Cf is a very strong neutron emitter, which makes it extremely radioactive and harmful. [24] [25] [26] 252 Cf, 96.9% of the time, alpha decays to curium-248; the other 3.1% of decays are spontaneous fission. [11] One microgram (μg) of 252 Cf emits 2.3 million neutrons per second, an average of 3.7 neutrons per spontaneous fission. [27]
Some isotopes undergo spontaneous fission (SF) with emission of neutrons.The most common spontaneous fission source is the isotope californium-252. 252 Cf and all other SF neutron sources are made by irradiating uranium or a transuranic element in a nuclear reactor, where neutrons are absorbed in the starting material and its subsequent reaction products, transmuting the starting material into ...
Nuclei which can decay by this process are described as lying beyond the neutron drip line. Two examples of isotopes that emit neutrons are beryllium-13 (decaying to beryllium-12 with a mean life 2.7 × 10 −21 s) and helium-5 (helium-4, 7 × 10 −22 s). [1] In tables of nuclear decay modes, neutron emission is commonly denoted by the ...
Heavier nuclides may be created instantaneously by physical processes, both natural (via the r-process) and artificial, though rapidly decay to more stable nuclides. As such, apart from minor decay branches in primordial radionuclides, spontaneous fission is not observed in nature. Observed fission half-lives range from 60 nanoseconds (252 104 Rf
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Rather than relying solely on a large amount of californium for neutrons, the multiplier effect of 3.5 pounds of uranium initiated by only a few milligrams of 252 Cf provided a higher ultimate neutron flux at a lower cost. The CFX was designed by IRT Corporation, [1] with two devices manufactured.
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