Californium (Cf) is an artificial element, and thus a standard atomic mass cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 245Cf in 1950. There are 20 known radioisotopes ranging from 237Cf to 256Cf and one nuclear isomer, 249mCf. The longest-lived isotope is 251Cf with a half-life of 900 years.
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Californium-252
Californium-252 (Cf-252) undergoes spontaneous fission and is used in small sized 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.
Uses
This isotope produces high neutron emissions and can be used for a number of applications in industries such as nuclear energy, medicine, and petrochemical exploration.
Nuclear Reactors
The neutron sources produced from Cf-252 are most notably used in the start-up of nuclear reactors. Once a reactor is filled with nuclear fuel, the stable neutron emissions from the source material initiates the chain reaction known as fission.
Military & Defense
The portable isotopic neutron spectroscopy (PINS) used by United States Armed Forces, the National Guard, Homeland Security, and U.S. Customs and Border Protection, employs the use of Cf-252 sources to detect hazardous contents found inside artillery projectiles, mortar projectiles, rockets, bombs, land mines, and improvised explosive devices (IED).
Oil & Petroleum
In the oil industry, Cf-252 neutron sources are used to find layers of petroleum and water in a well. Instrumentation is lowered into the well which bombards the formation with high energy neutrons to determine porosity, permeability, and hydrocarbon presence along the length of the borehole.
Medicine
Californium-252 has also been used in the treatment of serious forms of cancer. In patients suffering from certain types of brain and cervical cancer, Cf-252 can be used as a more cost-effective substitute for radium.