Compton Streuung - Highly differential studies

康普顿散射 - 高度差异化的研究

• 批准号: 421251772
• 负责人: Professor Dr. Reinhard Dörner
• 金额: --
• 依托单位: Institut für Kernphysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/421251772?language=en
• 关键词: Compton; Streuung; Highly; differential; studies

Compton scattering is one of the fundamental processes by which light interacts with matter, and it is the textbook example for demonstration of the particle nature of light. The process is a billiard type binary collision between a (high energy) photon and an electron, in which the photon is deflected and transfers part of its energy and momentum to the electron. Despite of its elementary and fundamental nature Compton scattering still poses major open questions today as emphasized by the programmatic title "Need for further inelastic scattering measurements at X-ray energies" of a review on the subject. There are three regimes, which are of particular interest: Firstly, the domain of low photon energies and/or small momentum transfers, where the binding energy of the electron is of the order of the energy transfer implied by the billiard-like collision scenario. Secondly, the regime of all processes in which electrons cannot be treated as independent particles, but the correlations are essential and, thirdly, the realm of molecular targets. It is these three regimes, which we will address, in the current project. To this end, we will perform the first ever coincidence experiments on Compton scattering on individual atoms and molecules in the gas phase. The experiments will be pursued at European synchrotron radiation facilities (PETRA3 in Hamburg, ESRF in Grenoble) where so called „pink“ beams (i.e. photon beams bypassing the monochromator) of sufficient photon flux are available for such measurements at extremely small low cross sections. We will use a COLTRIMS reaction microscope, co-developed by the group of the applicant, to measure the momentum vectors of electrons and ions created by Compton scattering with high resolution and 4π collection solid angle. From these two momentum vectors, the momentum and energy transfer of the scattered photon can be deduced from momentum conservation. Thus, from our experiment, we will obtain for all photon deflection angles and all energy transfers the respective angular emission distribution and energy spectrum of the ejected electron. Our experiments will be, 95 years after Arthur H. Compton’s fundamental discovery, be the first study in which for a free atom or molecule (gas phase) the momenta and directions of the scattered photon and the kicked electron are determined in coincidence. This will provide the most detailed and most complete view at Compton scattering ever achieved. Thus, besides their textbook character, our coincidence gas phase experiments will allow to address the open questions of Compton scattering in the afore mentioned three regimes. We will perform studies at low energies, where Compton scattering at a bound electron is energetically suppressed, investigate cases of Compton scattering, where electron-electron correlation is essential and explore Compton scattering in a molecule breaking the rotational symmetry of the process.

康普顿散射是光与物质相互作用的基本过程之一，它是演示光的粒子性质的教科书示例，该过程是（高能）光子和电子之间的台球式二元碰撞。尽管康普顿散射具有基本和基本的性质，但光子会偏转并将其部分能量和动量转移到电子，正如标题“需要在 X 射线上进行进一步的非弹性散射测量”所强调的那样，康普顿散射仍然提出了重大的悬而未决的问题。关于该主题的评论的“能量”。有三个特别令人感兴趣的领域：首先，低光子能量和/或小动量转移的领域，其中电子的结合能具有能量转移的量级其次，电子不能被视为独立粒子的所有过程的范围，但相关性是必不可少的；第三，我们将讨论的就是这三个范围。地址，在当前项目中。为此，我们将在气相中的单个原子和分子上进行首次康普顿散射实验。这些实验将在欧洲同步加速器辐射设施（汉堡的 PETRA3、格勒诺布尔的 ESRF）进行，这些设施被称为“粉红色”。具有足够光子通量的光束（即绕过单色仪的光子束）可用于在极小的低横截面进行此类测量，我们将使用由该团队共同开发的 COLTRIMS 反应显微镜。申请人，以高分辨率和 4π 收集立体角测量由康普顿散射产生的动量矢量，从这两个动量矢量，可以从动量守恒推导出散射光子的动量和能量转移。实验中，我们将获得所有光子偏转角度和所有能量转移的喷射电子的各自角发射分布和能谱，在 Arthur H. Compton 的基本发现 95 年后，我们的实验将成为最重要的。第一项研究，其中对于自由原子或分子（气相），散射光子和被踢电子的动量和方向是一致确定的，这将提供有史以来最详细和最完整的康普顿散射视图。他们的教科书特征，我们的重合气相实验将能够解决上述三种状态下的康普顿散射的开放问题，我们将在低能量下进行研究，其中束缚电子的康普顿散射被大力抑制，研究康普顿散射的情况。 ， 在哪里电子-电子关联是必不可少的，探索分子中康普顿散射打破旋转对称性的过程。