Abstract:
The Coulomb barrier plays a critical role in the low energy heavy-ion reaction. However, it can not be directly measured and needs to be extracted by different types of nuclear reactions. There have been many systematic studies on the Coulomb barrier so far, but most of them rely heavily on the interaction potential model and the reaction theory. In this work, the first-order derivative of the product of experimental fusion cross section and energy with respect to the energy was used as the penetration coefficient, and the position at which the penetration coefficient equals to half of its maximum was defined as the empirical barrier height. This definition does not depend on the theoretical model and has excellent stability and reliability. Based on this definition, the coupled-channels model CCFULL and Wong formula were used to fit 12 representative series of experimental fusion functions, and their Coulomb barrier heights were extracted. By comparing the heights extracted from the experimental values and the heights predicted by different theoretical potential models, and also their variation with the isospin asymmetry, it is found that the Bass80 and WKJ formulas are most consistent with the results of this work.
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