Study of neutrization effect for neutron dosimetry at low energy region

一般来说，中子与原子核的碰撞导致反冲原子离子和二次带电粒子形式的核反应产物。这些粒子的能量随入射中子的能量而变化。在诸如水和组织的含氢介质中，最重要的相互作用是与氢原子核（质子）的弹性散射，其占能量传递的90%以上。因此，质子被认为是估算中子感生辐射效应最重要的反冲粒子。反冲质子和其他离子在细胞中运动，反过来，与生物分子相互作用，导致DNA损伤和随后的生物病变。这些反冲质子中的大多数是低于1 MeV能量的低能粒子。因此，这项工作的动机是需要模拟生物物理建模所需的组织中中子相互作用中发射的低能质子的轨道。由于氢原子与氢原子的 关于我们 在计算低能质子的电子阻止本领时，需要考虑电荷交换过程（CEP）。在这项研究中，我们已经使用了当前的Monte Carlo轨道模拟技术的最新水平，并结合已发表的实验和建立的理论数据，开发一个模型，在低能量区的质子轨道模拟的扩展。为了了解反冲质子的行为，建立低能区的中子剂量学方法，我们开发了一个能在几MeV以下使用的质子径迹程序。与该准则有关的出版物（正在印刷中）载于《核仪器和方法》B部分（2002年）。通过微剂量计算评价中和质子的贡献。1 MeV中子的影响估计为24%。这一结果在国际医学物理学大会上发表。该研究的其他结果总结在参考文献中。少

In general, neutron collisions with atomic nuclei lead to recoil atomic ions and nuclear reaction products in the form of secondary charged particles. The energies of these particles vary according to the energy of the incident neutrons. In hydrogen containing media such as water and tissue the most important interaction is elastic scattering with hydrogen nuclei (protons), which accounts for more than 90% of energy transfer. Protons are, therefore, considered to be the most important recoil particles for estimating neutron induced radiation effect. The recoil protons and other ions set in motion in the cell, in turn, interact with the bio-molecule leading to DNA damage and subsequent biological lesions. Most of these recoil protons are low energy particles below 1 MeV energy. Therefore, the motivation for this work arises for a need to simulate the tracks of low energy protons emitted in neutron interactions in tissue as needed for biophysical modeling. As the hydrogen atom has a diff … More erent ionization cross section from that of the proton, charge exchange processes (CEP) need to be considered in order to calculate the electronic stopping power for low energy protons. In this study, we have used the current state of the art in the Monte Carlo track simulation techniques and in conjunction with the published experimental and established theoretical data to develop a model for the extension of the proton track simulation in the low energy region. We want to understand the behaviors of the recoil proton, and establish the neutron dosimetric methods at the low energy region.We developed a proton track code which can be used at the proton energy below several MeV. A publication related to this code is (in press) in the Nuclear Instruments and Methods section B (2002). Contribution of the neutralized proton is evaluated by a microdosimetric calculation. The effects for the 1 MeV neutrons are estimated to be 24%. This result was reported in the International congress on Medical Physics. The other results on this study are summarized in the reference. Less