Electron-positron pair production

正负电子对的产生

• 批准号: 416699545
• 负责人: Professor Dr. Carsten Müller
• 金额: --
• 依托单位: Lehrstuhl I: Plasmaphysik
• 依托单位国家: 德国
• 项目类别: Research Units
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/416699545?language=en
• 关键词: Electron; positron; pair; production

When an electron hits its antiparticle, a positron, both can annihilate into pure electromagnetic energy in the form of two photons. This reaction represents a striking example of Einstein‘s equivalence between mass and energy. In principle, the inverse process is possible as well: photons colliding with each other can transform their energy into mass by forming an electron-positron pair. Until now, this fundamental quantum process of matter creation purely from photon beams - which is named after Breit and Wheeler - could not directly be observed in experiment, though, since the requirements for obtaining a detectable signal are very high.Due to a sustained progress in high-intensity laser technology, the situation is currently changing. When an extremely intense optical laser pulse collides with a high-frequency photon beam (e.g. from bremsstrahlung), a strong-field version of the Breit-Wheeler process may occur: electron-positron pairs are created in photon-multiphoton collisions. In the relevant domain of nonperturbative parameters, the hitherto unobserved creation mechanism resembles a field-induced tunneling process by which the quantum vacuum decays into massive particles. However, the required field intensities can only be achieved by tight focusing of the laser light. Thereby a very complex spatio-temporal structure is imprinted on the electromagnetic fields.In view of planned experimental studies, the goal of the present project is to provide theoretical predictions for Breit-Wheeler pair production in focused high-intensity laser pulses. This poses a formidable challenge that shall be overcome by a suitable combination of scientific methods: analytical S-matrix calculations to obtain total production probabilities and momentum spectra of created particles are combined with numerical simulations based on a many-body description of the process via Vlasov equations. Both approaches can complement and amplify each other very well. In addition, during the second funding period, the closely related processes of multiphoton trident and Bethe-Heitler pair production in collisions of relativistic particle beams (electrons or bare ions) with focused laser pulses will be studied, with special attention being paid to similarities and differences with the strong-field Breit-Wheeler process.Aside from passing the computational challenges, we aim at answering conceptual questions, e.g. how radiation reaction can be incorporated consistently into the theoretical treatment of pair creation at ultrahigh intensities. Corresponding solutions can make important contributions to an improved understanding of the quantum vacuum under extreme-field conditions

当一个电子撞上它的反粒子，一个正电子，两者都可以湮灭成两个光子形式的纯电磁能量。这个反应是爱因斯坦质量与能量等价理论的一个显著例证。原则上，相反的过程也是可能的：光子相互碰撞可以通过形成电子-正电子对将它们的能量转化为质量。到目前为止，这种纯粹由光子光束产生物质的基本量子过程——以Breit和Wheeler的名字命名——还不能直接在实验中观察到，因为获得可探测信号的要求非常高。由于高强度激光技术的持续进步，这种情况目前正在改变。当一个极强的光学激光脉冲与一个高频光子束（例如来自轫致辐射）碰撞时，一个强场版本的布雷特-惠勒过程可能会发生：电子-正电子对在光子-多光子碰撞中产生。在非微扰参数的相关领域，迄今为止未观察到的创造机制类似于场诱导隧道过程，量子真空通过该过程衰变成大质量粒子。然而，所需的场强只能通过激光的紧密聚焦来实现。从而在电磁场上印上了非常复杂的时空结构。鉴于计划中的实验研究，本项目的目标是为聚焦高强度激光脉冲中Breit-Wheeler对的产生提供理论预测。这提出了一个艰巨的挑战，必须通过科学方法的适当组合来克服：分析s矩阵计算以获得总生产概率和创造粒子的动量谱，并结合基于弗拉索夫方程的多体描述过程的数值模拟。这两种方法可以很好地相互补充和放大。此外，在第二个资助期内，将研究相对论性粒子束（电子或裸离子）与聚焦激光脉冲碰撞产生多光子三叉戟和贝特-希特勒对的密切相关过程，并特别注意与强场Breit-Wheeler过程的异同。除了通过计算挑战之外，我们的目标是回答概念问题，例如如何将辐射反应始终纳入超高强度下对生成的理论处理中。相应的解可以为提高对极端场条件下量子真空的理解做出重要贡献