The synthesis of element 105 was reported by Soviet scientists at the research station in Dubna as early as 1967 and by scientists at U.C. Berkeley in 1970. The Soviet scientists reported synthesis by bombarding Am-243 with Ne-22. At Berkeley, Cf-249 was bombarded with N-15.
At the purported time of discovery the Soviets suggested the name Nielsbohrium (Ns) for the element while the American group suggested Hahnium (Ha). But the ensuing controversy over the discovery of this and other 6d-elements led the IUPAC to adopt its numerical system for naming elements beyond 103 until some agreements could be reached (hence Unp or Unnilpentium for 105).
The longest lived isotope has a half-life of 34 seconds. Dubnium is the name approved by the IUPAC in August 1997.
Stephen R. Marsden (ChemTopics)