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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]
The decay scheme of a radioactive substance is a graphical presentation of all the transitions occurring in a decay, and of their relationships. Examples are shown below. It is useful to think of the decay scheme as placed in a coordinate system, where the vertical axis is energy, increasing from bottom to top, and the horizontal axis is the proton number, increasing from left to right.
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.
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 ...
2.0 californium-237: 2.1 fluorine-23: 2.23 oxygen-22: 2.25 nobelium-252: 2.27 rutherfordium-255: 2.3 rutherfordium-262: 2.3 carbon-15: 2.449 radium-214: 2.46 rutherfordium-259m: 2.5 francium-204m1: 2.6 radium-213: 2.74 polonium-207m3: 2.79 nobelium-256: 2.91 bismuth-193m: 3.2 rutherfordium-259: 3.2 oxygen-21: 3.42 astatine-200m2: 3.5 radium-210 ...
They detected 8.2 MeV alpha particles with a half-life of 15 s. This activity was assigned to a Z=102 isotope. Later work suggests an assignment to 257 No, resulting most likely from the p5n channel with the 252 Cf component of the californium target. 249 Cf(12 C,αxn) 257−x No (x=2) This reaction was first studied in 1970 at the LBNL in a ...
The most efficient way to prepare this isotope is by α-decay of the californium isotope 252 Cf, which is available in relatively large amounts due to its long half-life (2.65 years). About 35–50 mg of 248 Cm is produced thus, per year.