Laboratory studies of neutral and collimated electron-positron beams

电子-正电子对等离子体(EPPS)代表了物质的一种独特状态，由此在带负电的(物质)和带正电的(反物质)粒子之间存在内在的和完全的对称性。EPPS以极端相对论风或准直喷流的形式，由宇宙中一些最具能量或最强大的物体发射，如黑洞、脉冲星和类星体。它们经常与以短暂(几毫秒到几分钟)爆发形式的伽马射线猛烈发射有关，这是在宇宙中观察到的最明亮的事件之一。这些系统代表着一个独特的天体物理实验室，因为它们与地球的遥远距离(有些超过10亿光年)提供了对宇宙早期阶段的宝贵洞察，并允许在最大限度上测试物理模型。然而，星系间介质中的EPPS的动力学，以及至关重要的是它们的辐射性质，仍然是社区中激烈辩论的主题，主要是因为我们对它们的了解本质上仅限于天体物理观测和数值模拟。宝贵的帮助自然会来自专门的实验室实验，在这些实验中，微物理可以以可重现和可控制的方式获得。然而，尽管世界上几个领先的研究机构做出了不懈的努力，但直到最近，在实验室中产生中性的EPP仍然是难以捉摸的。最近，我们的研究小组成功地在全光学实验装置中产生了中性EPP，使我们的研究小组走在了这一研究分支的前沿。这在该领域绝对是第一次，尽管世界各地的其他研究机构继续致力于这一努力。除了学术兴趣外，这项工作还吸引了大量媒体的关注，《新科学家》、《欧洲核子研究中心信使》、《物理世界》和《对话》等杂志的专题文章都证明了这一点。然后，我们提出的研究项目的重点是通过扩大我们对这种迷人的物质状态的实验研究，巩固我们在这一新兴实验物理学分支中的世界领先地位。特别是，我们的目标是第一次产生一个准直和中性的EPP，并研究它与厘米尺度上的背景电离介质的相互作用。我们的目标是在空间和时间上表征EPP传播过程中产生的不稳定性，从其早期阶段到饱和。关于等离子体动力学和随后的场产生的详细实验数据的提取将为天体物理喷流和伽玛暴发射的小规模研究提供第一个实验室平台，用于解释天体物理观测的数值模型可以与之进行比较和改进。

Electron-positron pair plasmas (EPPs) represent a unique state of matter, whereby an intrinsic and complete symmetry exists between the negatively charged (matter) and positively charged (anti-matter) particles. EPPs are emitted, in the form of ultra-relativistic winds or collimated jets, by some of the most energetic or powerful objects in the Universe, such as black-holes, pulsars, and quasars. They are frequently associated with violent emission of gamma-rays in the form of short-lived (milliseconds up to a few minutes) bursts, which are amongst the most luminous events ever observed in the Universe. These systems represent a unique astrophysical laboratory, since their immense distance from Earth (some exceeding a billion light years) provides invaluable insight into the Universe at its early stage and allow testing physical models at their very limits. However, the dynamics of EPPs in the intergalactic medium and, crucially, their radiative properties, are still subject of fervent debate in the community, chiefly due to the fact that our knowledge of them is intrinsically restricted to astrophysical observation and numerical modelling. Precious help would naturally arise from dedicated laboratory experiments, in which the microphysics can be accessed in a reproducible and controllable manner. However, despite dedicated efforts at several leading research institutes worldwide, the generation of a neutral EPP in the laboratory has until recently remained elusive. Recently, our research group has succeeded in generating a neutral EPP in a fully optical experimental setup, placing our group at the forefront of this research branch. This is an absolute first in the area, despite continued dedicated efforts from other research institutes worldwide. Besides the academic interest, this work has proven to attract significant media attention, as demonstrated by dedicated articles in the New Scientist, CERN Courier, Physics World, and The Conversation, among others. Our proposed research project is then focused on consolidating our world-leading role in this emerging branch of experimental physics by expanding our experimental investigations of this fascinating state of matter. In particular, we aim at generating, for the first time, a collimated and neutral EPP and study its interaction with a background ionised medium over cm scales. We aim at spatially and temporally characterising instabilities arising during the EPP propagation, from its early stages up to saturation. The extraction of detailed experimental data on the plasma dynamics and subsequent field generation will provide the first laboratory platform for the small-scale study of astrophysical jets and GRB emission, against which numerical models used to interpret astrophysical observations can be compared and refined.