Research development of microscopic track simulation codes for heavy ions

1.用蒙特卡罗方法模拟得到的辐射径迹结构（电离和激发的微观空间分布）对研究辐射效应有重要意义。我们开发了新一代低能质子和α粒子的径迹程序，程序中考虑了电荷交换过程和核弹性散射。2.方法在能量低于0.3MeVu^的范围内，<-1>对H^+和He^+&lt;++&gt;，通过电子俘获产生中性或修饰离子，如H^0或He^+和He ^0。收集和整理了所有这些粒子对水分子的实验和理论截面。利用自行开发的电子程序kurbuc对离子碰撞产生的二次电子进行了追踪。通过将各种物理参数与公布的数据3进行比较，证实了代码的可靠性。结果计算出的电子和核阻止本领、射程和W值与ICRU数据在10%的不确定度内一致。日 关于我们 e代码提供了各种微剂量学量，如径向剂量分布，限制阻止功率和线性能谱。这些数据与公布的数据吻合良好。结论新开发的低能质子码lephist和α粒子码leahist是“全慢化码”，而不是传统的“轨道段码”。对轨道结构研究领域的影响可能很大。质子的有效能量范围为1 keV至1 MeV，α粒子的有效能量范围为1 keV至8 MeV。因此，这对于从机理上理解中子和重离子在环境中的辐射效应是有用的。径迹结构确定了H_2O^+、H_2O^+和e_<sub>^-在物理阶段的产物。由于与水分子发生化学反应，这些产物立即形成自由基OH、H、e <aq>^-等。未来的目标是开发一个包容性的轨道结构代码，包括辐射化学作为时间的函数在10 μ s<-15>和10 μ <-6>s之间。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