Fermium

Fermium was first discovered in 1952 in the fallout from the “Ivy Mike” nuclear test (the first successful test of a hydrogen fusion bomb) in the South Pacific. Researchers identified a new plutonium-244 isotope on filter papers from a drone aircraft flown through the fallout. This discovery raised the possibility that the uranium nuclei could have absorbed still more neutrons, resulting in more new elements.

The researchers discovered einsteinium almost immediately on other filter papers but needed more material to see if there were any other new elements. Contaminated coral from the Enewetak Atoll was shipped to Berkeley for processing and analysis. About two months after the test, a new element was isolated, emitting high-energy particles with a half-life of about 20 hours. The discovery was kept secret on the orders of the US military until 1955 because of Cold War tensions.

From 1953 to 1954, the Berkeley team was able to prepare fermium in the lab by neutron bombardment of plutonium-239 in a cyclotron. They published their work in 1954 with a disclaimer that the results were not the first studies that had been carried out on the new element. The Ivy Mike studies were later declassified and published in 1955.

Meanwhile, a group of researchers at the Nobel Institute of Physics in Stockholm independently claimed discovery of element 100 by producing an isotope with a 30-minute half-life, publishing their work in May 1954. However, the historical precedence of the Berkeley team discovery was recognized and they got to name the new element. They named the element Fermium in honor of the recently deceased Enrico Fermi, who developed the first artificial self-sustained nuclear reactor.

Fermium is the heavy-weight champion of man-made elements that can be formed by neutron bombardment of lighter elements. It is highly radioactive. It is thought that fermium metal would have a silvery appearance; however, nobody knows much about this element. 

Because of the short half-lives of all fermium isotopes, and the fact that only very small amounts of fermium can be produced, fermium has no applications beyond basic scientific research.

Fermium has 20 isotopes. Fermium-257 is the longest-lived, with a half-life of 100.5 days. Fermium-252 has a half-life of three days, fermium-252 and fermium-255 have half-lives of about one day (25.4 hours and 20.1 hours, respectively), while fermium-251, fermium-254, and fermium-256 have half-lives of a couple of hours (5.3 hours, 3.2 hours, and 2.6 hours, respectively). The remaining isotopes have half-lives ranging from 30 minutes to less than a millisecond.

Because of the short half-life of all fermium isotopes, any that may have been present from the beginning of the formation of the Earth have long since decayed away. Einsteinium and fermium did occur in the natural nuclear fission reactor at Oklo (Earth’s two-billion-year-old, only known natural nuclear reactor), but they no longer exist.

Fermium is produced by the bombardment of lighter actinides with neutrons in nuclear reactors or accelerators. The major source of fermium is the High Flux Isotope Reactor at Oak Ridge National Laboratory in Tennessee.