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，它是表明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型二进制碰撞，其中光子被偏转，并将其能量和动量的一部分转移到电子中。尽管有基本和基本的自然散射，但如今，康普顿散射仍然存在着重大的开放问题，正如程序化标题“在X射线能量上需要进一步的无弹性散射测量的需求”，对该主题进行了评论。有三个特别感兴趣的机制：首先，低光子能量和/或小动量转移的结构域，其中电子的结合能是台球样碰撞场景所隐含的能量传递阶。其次，无法将电子被视为独立粒子的所有过程的制度，但相关性是必不可少的，第三是分子靶标的领域。这是这三个制度，我们将在当前项目中解决。为此，我们将对气相的单个原子和分子上的康普顿散射进行有史以来的第一个巧合实验。这些实验将在欧洲同步子辐射设施（汉堡的PETRA3，eSRF中的Grenoble中的PETRA3）进行，其中所谓的“粉红色梁（即绕过绕过单色光子器的光束（即光子光束）的足够光子滤光器）可用于在极小的低横截面上进行此类测量，我们将使用一个非常小的横截面。通过高分辨率和4π收集的稳态散射产生的电子和离子的载体。 H.康普顿的基本发现是第一项研究，其中自由原子或分子（气相）是散射光子和踢电子电子的动量和方向。这将在有史以来康普顿散射中提供最详细，最完整的视图。除了他们的教科书角色外，我们的巧合气体阶段实验还将允许在附近提到的三个制度中解决康普顿散射的开放问题。我们将在低能量上进行研究，其中康普顿在结合电子处的散射有效地抑制，研究康普顿散射的病例，其中电子电子相关性是必不可少的，并探索了分子中的康普顿散射，破坏了该过程的旋转对称性。