DISCOVERY OF THE TRANSFERMIUM ELEMENTS

In 1985 IUPAP and IUPAC decided to establish a Transfermium Working Group to consider questions of priority in the discovery of elements with nuclear charge number Z> 100. The membership of the Group was determined by the Unions in 1987. The Group met seven times for approximately one week each, three of the meetings being in the Laboratories of chief concern namely those at Berkeley, Darmstadt and Dubna. The work of the Group was carried out in two phases. Phase (i), the establishment of criteria that must be satisfied for the discovery of an element to be recognized, did not concern itself with individual cases or with priorities: it was carried out in close consultation with the Laboratories. The report on Phase (i), Part I of the present paper, was accepted by IUPAP and by IUPAC in 1990 and published separately (Pure and Appl. Chem. 63 (1991)879-886). The report on Phase (ii), the judgemental phase of the work of the Group, was accepted by the IUPAP Council in Madrid, Sept. 1991, and approved for publication by the IUPAC Bureau in Hamburg, Aug. 1991 and forms Parts II and III of the present paper. It completes the work of the Group by applying the criteria of Part I on an element-by-element basis; it considers and analyzes all the pertinent literature and discusses in chronological and critical detail those papers considered important for the building up of confidence that each element had been put in evidence. This delineation of discovery profiles results, in some cases, in a sharing of the credit for discovery.