Analysis of cross-section data used in the Monte Carlo track structure simulation

1)本研究的目的是对用于电子径迹结构码的水的截面进行比较和评价。本研究旨在阐明输入数据与物理和化学假设之间的差异在多大程度上影响辐射效应生物物理模拟的结果。2)用各种理论计算了二次电子的电离截面和能谱。对水蒸气横截面进行了分析，因为它们更丰富，更容易获得。所有适当发表的实验总电离截面都用适当的函数拟合，并用于生成电子径迹。利用三组汇编的数据对总激励截面和平均激励能进行比较。3)利用蒙特卡罗航迹编码生成的不同截面组合的航迹，从相互作用的径向分布和点核的角度进行比较。发现电离过程中发射的二次电子谱是影响这些量的最重要因素。不同的激发和弹性散射截面对电子径迹结构的影响不像电离截面那么大。结论是，目前用于生物物理建模的所有代码，使用不同的横截面和不同的阶段，在较大的目标中表现出密切的相似性，而在DNA大小的目标中观察到明显的差异。4)我们建议对所有可用的总电离和弹性截面的实验数据进行拟合函数。我们得出结论，大多数代码产生的轨迹与总停止功率和总断链率等宏观量是合理一致的。然而，我们预测了轨道上聚类频率的差异。

1) The purpose of this study is to make an intercomparison and assessment of cross sections for water used in electron track structure codes. This study is intended to shed light on to what extend the differences between the input data and physical and chemical assumptions influence the outcome in biophysical modelling of radiation effects.2) lonisation cross sections and spectra of secondary electrons were calculated by various theories. The analyses were carried out for water vapor cross sections as these are more abundant and readily available. All suitably published experimental total ionization cross sections were fitted by an appropriate function and used for generation of electron tracks. Three sets of compiled data were used for comparison of total excitation cross sections and mean excitation energy.3) The tracks generated by a Monte Carlo track code, using various combinations of cross sections, were compared in terms of radial distributions of interactions and point kernels. The spectrum of secondary electrons emitted by the ionization process was found to be the most influential factor on these quantities. A different set of cross sections for excitation and elastic scattering did not affect the electron track structure as much as did ionization cross sections. It is concluded that all codes, using different cross sections and in different phase, currently used for biophysical modelling exhibit close similarities in larger size targets while appreciable differences are observed at DNA size targets.4) We recommend fitted functions to all available suitable experimental data for the total ionization and elastic cross sections. We conclude that most codes produce tracks in reasonable agreement with the macroscopic quantities such as total stopping power and total yield of strand breaks. However, we predict differences in frequencies of clustering in track.