Simulation of the fission dynamics of the excited compound nuclei ^206Po and ^168Yb produced in the reactions ^12C＋^194Pt and ^18O＋^150Sm

A two-dimensional dynamical model based on the Langevin equation was used to study the fission dynamics of the compound nuclei ^206Po and ^168Yb produced in the reactions ^12C＋^194Pt and ^18O＋^150Sm,respectively.The fission cross section and average pre-scission neutron multiplicity were calculated for the compound nuclei ^206Po and ^168Yb,and results of the calculations compared with the experimental data.The elongation coordinate was used as the first dimension and the projection of the total spin of the compound nucleus onto the symmetry axis,K,considered as the second dimension in the Langevin dynamical calculations.In the two-dimensional calculations,a constant dissipation coefficient of K and a non-constant dissipation coefficient have been used to reproduce the abovementioned experimental data.It is shown that the two-dimensional Langevin equation can satisfactorily reproduce the fission cross section and average pre-scission neutron multiplicity for the compound nuclei ^206Po and ^168Yb by using constant values of the dissipation coefficient of K equal to γκ=0.18（MeV zs）^-1/2 and γκ= 0.20（MeV zs）^-1/2for the compound nuclei ^206Po and ^168Yb,respectively.

角动量对基于裂变截面探测核耗散的影响(英文)

核耗散降低了裂变截面值(σdrop f)。基于Langevin模型,研究了角动量对σdrop f作为鞍点前摩擦强度β函数的影响。发现在低自旋,摩擦对σdrop1f的影响显著增强。通过考察系统95Bi,201Bi和207Bi的σdrop f随β的演化,发现摩擦效应随着Bi核中质比(N/Z)的增加而变大。这些结果建议,为了更好地在实验上用裂变截面探测β,应产生那些具有低自旋、高N/Z的热核系统。