高速重离子混合束中Xe离子的特征X射线鉴别实验设计研究

Design an Experiment to Identify Characteristic X-ray Spectrum Emitted by Xe Ion in Fast Mixed Heavy Ions

空间重离子单粒子效应模拟试验技术依赖于串列静电加速器和回旋加速器,重离子回旋加速器通常使用ECR离子源进行离子注入,但这也往往导致引出的离子种类比较复杂。同时因为加速器中混合离子的荷质比相近,所以对引出离子进行准确鉴别具有一定难度。相关研究显示高速高电荷态重离子和原子发生碰撞之后,将使核外电子发生跃迁处于激发态,且电子在退激发过程中发射特征X射线,因此可以通过测量特征X射线能谱进而鉴别加速器引出的重离子种类。以Xe离子为例,本文研究了Xe离子与固体靶原子发生碰撞过程中截面差异和产生特征X射线能量区别。同时结合不同类型探测器的特性与加速器的相关参数,在回旋加速器注入前端设计并建立了一套利用特征X射线进行重离子种类鉴别的装置。基于此装置可以实现ECR混合离子源引出离子种类的准确鉴别,为开展重离子单粒子效应辐照实验提供有效的离子种类分析方法。

There are a lot of particles in space,including protons and heavy ions mainly.These particles in space can induce different radiation effects on the electronic devices,such as single event effect and displacement damage.The single event effect is the main reason of the abnormal function in spacecraft.Astronautical electronic devices have to be tested in similar radiation environment before applied in spacecraft.However,it is difficult to test all devices in space or to create a space-like radiation environment.As a result,the experiments on the ground have mainly relied on the tandem accelerator and the cyclotron accelerator.The cyclotron accelerators usually use an ECR ion source for injection,which mean that ion species are more complex than the tandem accelerators.It makes identification difficult by mass spectrometer because the ECR ion source injected different ions with the similar charge-mass ratio into the cyclotron accelerator at the same time.We need to find a new way to distinguish the ions with similar charge-mass ratio in the cyclotron accelerators.There are some studies about the collisions between fast heavy ions and atom targets.When the fast highly charge ion collided with atom targets,they both will emit the characteristic X-ray due to the electron transitions in different shells.Thus it is possible to identify the ions by their different characteristic X-ray spectra.An experiment design was carried out to identify Xe using this technique by these considerations,including the Xe cross section by different atom targets,the characteristic X-ray energy,the photo detectors,and other factors.Firstly,Ag and Mo were chosen as atom targets according to previous experimental data on the X-ray yield of Xe colliding with different atoms.Secondly,the HPGe detector was chosen to detect the X-ray according to the comparison of the characteristic X-ray of Xe,Ag and Mo,and the energy resolution required better than 10 keV.Thirdly,the angle of detecting X-ray would affect the X-ray energy gently.Another the Mylar/Kapton film will degenerate the X-ray intensity similarly,the Mylar film has more strength in a vacuum condition.Finally,an experimental layout figure was draw according to all above the considerations.In conclusion,this work is a preliminary development of a heavy ion identification device.It could be useful for the analysis of mixed heavy ions in the ECR ion source,which is used in test experiments for the single event effect.