摘要
我们用粒子鉴别系统测量了31.2 MeV的α粒子在^(11,10)B核上的(α,t)、(α,d)、和(α,p)反应的角分布;由出射粒子的能谱,我们分别得到了剩余核处于基态和不同激发态的十个角分布。从角分布的形状看,在^(11)B(α,t_0)^(12)C_(g·s),^(11)B(α,d_0)^(13)C_(g·s),^(10)B(α,d_0)^(12)C_(g·s),^(10)B(α,d_1)^(12)C_(1st),^(11)B(α,P_0)^(14)C_(g·s)等反应中均有不同程度的后角上翘;并且(α,t_0)和(α,P_0)的后角上翘的同位素效应似乎与(α,α)的反常散射的同位素效应相反。最后,我们采用了直接核反应的色散关系理论,用费曼顶点图和顶三角图解,计算了奇点位置,定性地讨论了其主要反应机制,我们得出的初步结论是:在前角区主要是直接削裂,在后角区则是重粒子削裂的交换机制。而^(11)B(α,d_0)^(13)C_(g·s)的后角区却是多种反应机制的叠加结果。
Angular distribution for (α, t), (α, d) and (α, p) reactions of α particle on nuclei ^(10, 11)B at 31.2 MeV incident energy have been measured by particle identification system. The shapes of the outgoing particle angular distribution show that the cross sections in backward angular region have different enhacement in ^(11)B(α, t_0)×^(12)C_(g.s.), ^(11)(α, d_0)^(13)C_(g.s.), ^(10)B(α, d_0)^(12)C_(g.s.), ^(10)B(α, d_1)^(12)C_(1st), ^(11)B(α, p_0)^(14)C_(g.s.) and the isotopic effect of the backward angle anomaly in the reac tions (α, p_0) and (α, t_0) is just opposed to that of (α, α) elastic scattering from nucleus B.Finally, the reaction mechanism is discussed qualitatively in terms of the Dispersion Theory of direct nuclear reaction. The calculation of the singularity position of the (α, t), (α, d) and (α, p) reactions on nuclei ^(10, 11)B is performed using the Feynman Graphs. The initial conclusion is the following:The principal mechanism is direct stripping in the for-ward angle region and heavy partide stripping in the backward angle region.For the reaction ^(11)B(α, d_0)^(13)C_(g.s.) however, there is a multimechanism superposition in the backward angle region.
