In 1964, workers at the Joint Nuclear Research Institute at Dubna (U.S.S.R.) bombardedplutonium with accelerated 113 to 115 MeV neon ions. By measuring fission tracks in aspecial glass with a microscope, they detected an isotope that decays by spontaneousfission. They suggested that this isotope, which had a half-life of 0.3 +/- 0.1 s might be260-104, produced by the following reaction: 242Pu + 22Ne --> 104 +4n.

Element 104, the first transactinide element, is expected to have chemical propertiessimilar to those of hafnium. It would, forexample, form a relatively volatile compound with chlorine(a tetrachloride).

The Soviet scientists have performed experiments aimed at chemical identification, andhave attempted to show that the 0.3-s activity is more volatile than that of therelatively nonvolatile actinide trichlorides. This experiment does not fulfill the test ofchemically separating the new element from all others, but it provides important evidencefor evaluation.

New data, reportedly issued by Soviet scientists, have reduced the half-life of theisotope they worked with from 0.3 to 0.15 s. The Dubna scientists suggest the name kurchatoviumand symbol Ku for element 104, in honor of Igor Vasilevich Kurchatov (1903-1960),former Head of Soviet Nuclear Research.