Research development of microscopic track simulation codes for heavy ions

1. 蒙特卡罗模拟得到的辐射轨迹结构（电离和激发的微观空间分布）对辐射效应的研究有重要意义。我们开发了考虑电荷交换过程和核弹性散射的新一代低能质子和α粒子轨迹码。方法在H^+和He^<++>的能量小于0.3MeVu^<-1>的范围内，通过电子捕获产生中性离子或修饰离子，如H^0或He^+和He^0。收集和整理了所有这些水分子的实验和理论截面。用自行研制的kurbuc电子代码对离子碰撞产生的二次电子进行了跟踪。通过将各种物理参数与公布的数据进行比较，证实了代码的可靠性。结果计算的电子和核停止功率、范围和W值与ICRU数据在10%的不确定度内一致。More e代码提供了各种微剂量学量，如径向剂量分布、限制停止功率和线性能谱。这些数据与已发表的数据吻合良好。结论新开发的质子码lephist和α粒子码leahist是“全慢化码”，而不是传统的“轨道段码”。这对轨道结构研究领域的影响可能是很大的。质子的有效能量范围为1 keV至1 MeV，粒子的有效能量范围为1 keV至8 MeV。因此，这对于理解中子和重离子在环境中的辐射效应的机理是有帮助的。径迹结构识别了物理阶段H_2O^+、H_2O^+和e_<sub>^-的产物。这些产物通过与水分子的化学反应，立即形成OH、H、e_<aq>^-等自由基。未来的目标是开发一个包含辐射化学的轨道结构代码，作为时间在10^<-15>到10^<-6>之间的函数。少

1. IntroductionRadiation track structure (microscopic spatial distributions of ionization and excitation) obtained by Monte Carlo simulation contributes significantly to research of radiation effects. We have developed new generation track codes for low-energy protons and alpha particles, in which charge exchange processes and nuclear elastic scattering are taken into account.2.MethodsIn the energy range below 0.3MeVu^<-1> for H^+ and He^<++>, neutral or dressed ions such as H^0 or He^+ and He^0 are generated by electron capture. Experimental and theoretical cross sections for all these particles for water molecule were collected and compiled. Secondary electrons ejected by ion impact were traced by the electron code kurbuc developed by ourselves. The reliability of the codes was confirmed by comparing the various physical parameters with the published data3. ResultsCalculated electronic and nuclear stopping powers, ranges and W values agreed with ICRU data within 10% uncertainties. Th … More e codes provided various microdosimetric quantities such as radial dose distributions, restricted stopping powers and lineal energy spectra. These data were in good agreement with the published data.4. ConclusionsNewly developed low-energy codes, lephist for protons and leahist for alpha particles, are "full slowing down codes", not "track segment code" conventionally used. The impact on the research field of track structure may be large. The effective energy ranges are 1 keV to 1 MeV for protons and 1 keV to 8 MeV for alpha particles. Therefore, these are useful for applications to the mechanistic understanding of radiation effects of neutrons and heavy ions in environment. Track structure identifies the products of H_2O^+, H_2O^+ and e_<sub>^- at the physical stage. These products immediately form the radicals, OH, H, e_<aq>^-, and so on, due to chemical reactions with water molecules. The future objective is to develop an inclusive track structure code including radiation chemistry as a function of time between 10^<-15> and 10^<-6>s. Less