TABLE OF CONTENTS D.C.Hoffman, D.M.Lee
Nuclear Science Division, MS-70/319, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
The long quest to detect Superheavy Elements (SHEs) that might exist in nature and the efforts to artificially synthesize them at accelerators or in multiple-neutron capture reactions is briefly reviewed. Recent reports of the production and detection of the SHEs 114, 116, and 118 are summarized and discussed. Implications of these discoveries and the prospects for the existence and discovery of additional SHE species are considered.
The possibility of relatively stable elements well beyond uranium, the heaviest element found in large quantities in nature, was considered in the early 1950 s. This interest was sparked by the totally unexpected discovery of the new elements 99 (einsteinium) and 100 (fermium) in debris from the first U.S. thermonuclear device Mike , tested on Eniwetok Atoll in the South Pacific on November 1, 1952 by the Los Alamos Scientific Laboratory. Prior to that discovery, only the elements through californium (atomic number 98) were known. Scientists postulated that the enormous, nearly instantaneous high neutron flux generated in the 10-megaton detonation of Mike resulted in the successive capture of at least 17 neutrons in the uranium-238 ( 238U) present in the device. In this way, the heavier uranium isotopes through 255U were produced and many of these isotopes decayed rapidly by successive emission of negatively charged ? particles to produce isotopes of known elements with atomic numbers of 93 through 98. The uranium...
