Theoretical Study of the Reaction Mechanism of Low Energy Heavy Ion Collisions

1. 研究了核本征自由度对重离子聚变反应的影响。主要研究结果如下：(1)核振动激发模式极大地增强了亚能垒处的聚变截面。(2)这种增强主要是由于大的电位重整化。(3) <^(74)Ge>和<^(74)Ge>碰撞的异常大增强表明，在统一体系中引起了<^(74)Ge>的大变形。(4)对于重系统，耦合通道方程的维数可以大大降低。(5)绝热隧穿极限下的聚变反应有一种几何解释。推导了低能重离子碰撞中核表面振动激发引起的能量耗散和角动量耗散的延迟摩擦函数。然后我们澄清了耗散机制与入射能量的关系。我们推导出了一个计算多维系统中量子隧穿微观自由度滞后的公式。然后将该方法应用于μ子催化的d-t聚变，结果表明，非绝热性使μ子对聚变合成的α粒子的粘着概率降低了约30%。将魏登穆勒的新统计理论应用于核预平衡过程。在弱耦合极限上与Agassi等人的结果一致，而在强耦合极限上存在差异。并用该方法计算了水平密度。利用时间相关平均场理论（TDMF）计算了弹性散射和吸收截面。我们证明了重离子反应的惊奇分析中的<根b> E约束是由激子数约束引起的。同时，我们通过考虑角动量计算了激子模型的能级密度。

1. We studied the effects of nuclear intrinsic degrees of freedom on the heavy ion fusion reactions. Our main results are: (1) Nuclear vibrational modes of excitation largely enhance the fusion cross section at sub-barrier energies. (2) This enhancement is mainly due to the large potential renormalization. (3) The extra-ordinarily large enhancement for the <^(74)Ge> and <^(74)Ge> collision suggests that a large deformation of <^(74)Ge> is induced in the unified system. (4) The dimension of the coupled-channels equations can be considerably reduced for heavy systems. (5) A geometrical interpretation holds for the fusion reaction in the limit of adiabatic tunneling.2. We derived the retarded friction functions for the energy and the angular momentum dissipation due to nuclear surface vibrational excitation in low energy heavy ion collisions. We then clarified the dependence of the dissipation mechanism on the incident energy.3. We derived a formula, which determines the lag of microscopic degrees of freedom in quantum tunneling in multi-dimensional systems. This method was then applied to the muon catalyzed d-t fusion, and showed that the mon-adiabaticity reduces the sticking probability of the muon to the fusion synthesized alpha particle by about 30 %.4. We applied Weidenmuller's new statistical theory to nuclear pre-equilibrium process. The result agreed with that of Agassi et al. in the limit of weak coupling, but differes in the strong coupling limit. Also, the level density was calculated by this method.5. We calculated the elastic scattering and the absorption cross sections using a time dependent mean field theory (TDMF).6. We showed that the <root> E constraint in the surprisal analysis of heavy ion reactions arises from a constraint to the exciton number. Also, we calculated the level density for the exciton model by taking into account the angular momentum.