INFLUENCE OF HEAVY TARGETS AND COMPOUND NUCLEI ON FUSION EXCITATION FUNCTION MECHANISM

摘要

Fusion cross sections induced by ~(4,6,8)He and ~7Li were studied using different reactions [(~4He+~(209)Bi, ~4He+~(208)Pb, ~4He+~(197)Au), (~6He+~(209)Bi, ~6He+~(206)Pb, ~6He+~(197)Au) and (~8He+~(209)Bi, ~8He+~(204)Pb, ~8He+~(197)Au)], these reactions were used to determine the influence of the heavy targets on the fusion excitation function mechanism. The reactions [~4He+~(208)Pb, ~6He+~(206)Pb, ~8He+~(204)Pb] give the same compound nuclei ~(212)Po and the reactions (~6He+~(209)Bi and ~7Li+~(208)Pb) give the same compound nuclei ~(215)At. These reactions were used to determine the influence of the compound nuclei on fusion excitation function mechanism. Theoretical calculations were done using the Channel Coupling code of the NRV using W. S. Surface with different parameters （V_o, r_(o,) ~(Col)r_o, a and ?ω_β） for all reactions. The current study has shown that, large enhancement in the fusion cross sections at energies at the Coulomb barrier were observed only in the reactions ~6He+~(206)Pb and ~8He+~(204)Pb compared with ~4He+~(208)Pb and slightly or no enhancement were observed in the reactions ~(6,8)He+~(209)Bi and ~(6,8)He+~(197)Au compared with reactions induced by ~4He.