科研之友
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摘要
A systematic theoretical study of alpha-decay half-lives in the superheavy mass region of the periodic table of elements is carried out by extending the quantum-mechanical fragmentation theory based on the preformed cluster model (PCM) to include temperature (T) dependence in its built-in preformation and penetration probabilities of decay fragments. Earlier, the alpha-decay chains of the isotopes of Z = 115 were investigated by using the standard PCM for spontaneous decays, with "hot-optimum" orientation effects included, which required a constant scaling factor of 104 to approach the available experimental data. In the present approach of the PCM (T not equal 0), the temperature effects are included via the recoil energy of the residual superheavy nucleus (SHN) left after x-neutron emission from the superheavy compound nucleus. The important result is that the alpha-decay half-lives calculated by the PCM (T not equal 0) match the experimental data nearly exactly, without using any scaling factor of the type used in the PCM. Note that the PCM (T not equal 0) is an equivalent of the dynamical cluster-decay model for heavy-ion collisions at angular momentum l = 0. The only parameter of model is the neck-length parameter Delta R, which for the calculated half-lives of alpha-decay chains of various isotopes of Z = 113 to 118 nuclei formed in "hot-fusion" reactions is found to be nearly constant, i.e., Delta R approximate to 0.95 +/- 0.05 fm for all the alpha-decay chains studied. The use of recoiled residue nucleus as a secondary heavy-ion beam for nuclear reactions has also been suggested in the past.
- 出版日期2015-5-11
