科研之友
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摘要
Within a modified unified fission model approach, the alpha decay half-lives of 108 even-even isotopes of heavy nuclei are studied first for the use of different nuclear surface energy coefficients (gamma - MN76, gamma - MN95, gamma - MS67 and gamma - MS00) entering in the calculation of proximity potential, for the use of two different forms of overlapping potentials, linear and second-order polynomial forms. Exact fitting of the half-lives for the isotopes of Ra, Th and U is obtained by introducing a parameter Delta R, which extends the touching point radius. A linear relation connecting this parameter Delta R and Q-value of the decay is obtained with a constraint to have a continuity of the potential in the overlapping and non-overlapping regions. For the use of this linear relation, half-life values are calculated for all the 108 even-even isotopes of heavy nuclei. The pre-existence probability is also calculated as the penetrability of the overlapping region for the use of two different forms of overlapping potentials, linear and second-order polynomial forms. The pre-existence probability and penetration probability calculations reveal the associated nuclear structure effects. Calculated half-lives for the use of different versions of nuclear surface energy coefficients, using both linear and polynomial overlapping potentials, compare well with the experimental values. Nuclear surface energy coefficient (gamma - MS00) due to Myers and Swiatecki gives the least deviation. Further, for the use of both linear and polynomial overlapping potentials using the gamma - MS00 version of the surface energy coefficient the half-lives of experimentally known superheavy elements are calculated and the calculations are also extended to predict half-lives of yet experimentally unknown nuclei.
- 出版日期2013-3
