science · 17 March 1950 · 75 years ago
In 1950, a new radioactive element, element 98, named “californium” was announced by scientists at the University of California at Berkeley. This is a synthetic chemical element of the actinide series in Group IIIb of the periodic table, isotope californium-245. The scientists Stanley G. Thompson, Kenneth Street, Jr., Albert Ghiorso, and Glenn T. Seaborg produced it by bombarding curium-242 (atomic number 96) with helium-ions in the 60-inch cyclotron. Since then, longer lived isotopes have been created, including californium-251 with an 800-year half-life, and microgram quantities of compounds such as the oxychloride CfOCl, the oxide Cf2O3, and the trichloride CfCl3. Also, californium-252, with a half-life of 2.65-years, has industrial and medical applications as a very intense point source of neutrons. Used as a neutron emitter and to analyze the sulfur content of petroleum and to measure the moisture content of soil..
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