Dubnium: historical information
Dubnium apparently was synthesized by Russian and American workers independently by bombardment technologies. Its actual isolation as the free element has not been accomplished. In 1967, Flerov reported element 105 after experiments at the Joint Research Institute in Russia involving reactions between 243Am ions with 22Ne ions. In 1970, Ghiorso and others announced their synthesis of dubnium at Berkeley (California) in the USA. This method involved the collsion of 249Cf ions with 15N ions.