X-ray studies of materials modified by high energy ion beams

当高能重离子撞击固体目标，如硅或玻璃时，它会产生一个狭长的圆柱形损伤，即所谓的离子轨迹。许多年来，许多人都相信离子轨道会融化，即使是如此短暂（不到一纳秒）。然而，没有令人信服的证据存在，这是一个遗憾，因为这些离子撞击发生的频率比大多数人想象的要高（离子束处理，核废料储存，宇宙射线干扰）。我打算提供这样的证据，并将在我的提案中解释如何。

When an energetic, heavy ion hits a solid target such as silicon or glass, it creates a long and narrow cylinder of damage, the so-called ion track. It is believed by many, and since many years, that the ion track melts, if ever so briefly (for less than a nano-second). However, no convincing proof exist and that is a pity, because these ion impacts happen more often than most would think (ion beam processing, nuclear waste storage, cosmic ray interference). I am planning to provide exactly such evidence, and will explain how in my proposal. The planned experiment will take place in amorphous silicon, and I plan to discover other fundamental properties of this important material as well. For example, we have recently shown that a-Si is "hyperuniform", a property it shares with cristalline (non-amorphous) materials but not with liquids and we plan to study its close cousin, amorphous germanium, because we expect it to be even more "hyperuniform". In the course of the hyperuniformity measurements, we discovered a small but significant peak in the diffraction pattern of amorphous silicon that should not be there, and I describe in the proposal how we are going to find out what causes it. One important application of disordered materials is for the conversion of light to electricity. In this proposal, I present two projects to improve devices that do this type of conversion: one is aimed to improve the response time of a new type of (highly sensitive) infra-red detector and another aims to improve the conversion efficiency of plastic solar cells.