Electron emission from condensed phase material induced by fast protons.
Electron emission from condensed phase material induced by fast protons.
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由快质子引起的凝聚相材料的电子发射。
DOI：
10.1093/rpd/ncq529
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发表时间：
2011
影响因子：
1
通讯作者：
Toburen,LH
中科院分区：
文献类型：
--
作者：
Shinpaugh,JL;McLawhorn,RA;McLawhorn,SL;Carnes,KD;Dingfelder,M;Travia,A;Toburen,LH
蒙特卡罗径迹模拟已成为放射生物学研究的重要工具。蒙特卡罗输运程序通常依赖于弹性和非弹性电子散射截面，这些截面是使用补充气相数据的理论方法确定的;实验凝聚相数据通常不可用或不可行。理论方法中最大的不确定性存在于低能电子中，这对于模拟电子轨道末端很重要。为了测试这些代码处理低能电子输运的可靠性，在快速质子通过后测量了从薄箔中射出的低能二次电子的产率。快离子，其中相互作用截面是众所周知的，提供了低能量电子的初始光谱，该低能量电子随后在离开箔表面并被检测之前在材料中经历弹性和非弹性散射。这些数据，作为一个功能的能量和角度的新兴电子测量，可以提供测试的物理电子传输。从无定形固体水冻结到铜基板的初步测量表明与MC模拟的实质性分歧，虽然问题仍然存在，因为目标充电。最近的研究，使用不同的冷冻技术，没有表现出充电，但证实了理论和实验之间的分歧。人们现在有了更多的关于铜、铝和金的绝对微分电子产额的数据，以及冷冻碳氢化合物薄膜的数据。提供了代表性数据。
Monte Carlo track simulation has become an important tool in radiobiology. Monte Carlo transport codes commonly rely on elastic and inelastic electron scattering cross sections determined using theoretical methods supplemented with gas-phase data; experimental condensed phase data are often unavailable or infeasible. The largest uncertainties in the theoretical methods exist for low-energy electrons, which are important for simulating electron track ends. To test the reliability of these codes to deal with low-energy electron transport, yields of low-energy secondary electrons ejected from thin foils have been measured following passage of fast protons. Fast ions, where interaction cross sections are well known, provide the initial spectrum of low-energy electrons that subsequently undergo elastic and inelastic scattering in the material before exiting the foil surface and being detected. These data, measured as a function of the energy and angle of the emerging electrons, can provide tests of the physics of electron transport. Initial measurements from amorphous solid water frozen to a copper substrate indicated substantial disagreement with MC simulation, although questions remained because of target charging. More recent studies, using different freezing techniques, do not exhibit charging, but confirm the disagreement seen earlier between theory and experiment. One now has additional data on theabsolutedifferential electron yields from copper, aluminum and gold, as well as for thin films of frozen hydrocarbons. Representative data are presented.