New Experimental Insights into the Production of Superheavy Elements Using Heavy Ion Reactions

摘要

Attempts at the Lawrence Berkeley Laboratory to produce superheavy elements (SHE) by using the reactions of exp 48 Ca with exp 248 Cm and exp 136 Xe with exp 238 U have been unsuccessful. These negative results led researchers to consider the possibility that these reactions (and their associated mechanisms) do not lead to the formation of superheavy nuclei with sufficiently low excitation energies. Consequently, the number of surviving atoms of superheavy elements is well below detection thresholds, even for relatively low estimates for prompt fission losses. A summary of some new experimental evidence supporting the above hypothesis is presented, and possible alternative heavy-ion--heavy-target combinations are suggested for SHE synthesis. 10 figures, 1 table, 43 references. (ERA citation 03:049001)