Fermium is obtained on cyclotron bombardment of Thorium, Uranium or Plutonium by accelerated ions of Nitrogen, Helium or Carbon, respectively as well as by neutron irradiation of Plutonium, Curium or Californium in reactors. 257Fm is produced in largest quantities, around 109 atoms annually. In optimal conditions several µgs of 257Fm may be synthesized from 1gramm of 252Cf.
The first Fermium had been produced by simultaneous neutron trapping by Uranium with consequent β--decay.
238U92 + 17n -> 255U92 --(8β-)--> 255Fm100
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