Investigation of unexpectedly high-energy electron emission from water vapor by the impact of carbon ions with Bragg-peak energies and track analysis

在此基础上，我们成功地测量了具有布拉格峰能量的碳离子对水蒸气二次电子发射的绝对双微分截面（DDCS）。单微分截面（SDCS）与CDW-EIS理论计算结果在反向角（> - 100°）的角度分布不一致，而单微分截面（SDCS）与CDW-EIS理论计算结果吻合较好，特别是在低能区（<200 eV），说明对于入射能量为几MeV/u或更高的重离子碰撞，费米-穿梭加速度对离子-原子碰撞的贡献很小。由蒙特卡罗轨迹模拟推导出的碳离子径向剂量分布与Chatterjee模型的比较表明，在核心区存在有意义的显著差异，表明模型有必要进行修正。

Further improving our previous apparatus, we have successfully measured absolute double differential cross section(DDCS) for secondary electron emission from water vapor by the impact of carbon ions with Bragg-peak energies. The angular distributions of DDCSs disagreed with the CDW-EIS theoretical calculation at the backward angles(> 100°), while single differential cross section(SDCS) agreed well with the CDW-EIS, particularly in the low-energy region(<200 eV), suggesting the contribution of Fermi-Shuttle acceleration to the ion-atom collisions is rather small for heavy-ion impact with incident energies of several MeV/u or higher. Comparisons of radial dose distributions for the carbon ions, deduced form Monte-carlo track simulation, with the Chatterjee model showed meaningful and significant discrepancies in the core region, implying the necessity of corrections of the model.