TRANSURANIUM ELEMENTS—SEABORG 261 
at the University of California at Berkeley. A similar accelerator is 
in operation at Yale University. Russia has shown a great interest 
in heavy ions and their application to the synthesis of transuranium 
elements and has accelerators for heavy ions under construction. 
Even with use of heavy ions, however, the source of target materials 
will present serious problems. New, expensive, high-flux reactors, 
producing 101° to 10'° neutrons per square centimeter per second, are 
needed in order to prepare even milligram amounts of berkelium, 
californium, and einsteinium within a reasonable space of time. 
This short article has, of necessity, omitted even reference to many 
of the important aspects of the transuranium element field. In par- 
ticular, it has not been possible to capture the international flavor of 
the work which has gone on in recent years. The emphasis has been 
on the chemical properties, the historical aspects, and the possibilities 
for future advances in this field. Much of interest could be told of the 
methods of production and of the many new long-lived isotopes which 
are becoming available in weighable amounts. The nuclear properties, 
which were barely mentioned, are of great interest. Over 80 isotopes 
of the transuranium elements are now known. The decay properties 
of these have been of great importance for the development of the 
Copenhagen school’s unified model of the nucleus, and the induced and 
spontaneous fission properties of such isotopes are very important to 
the future development of a satisfactory theory for the nuclear-fission 
process. 
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