First steps towards atomic physics of fast ion-slow ion collisions

这个项目的主要目的是研究快离子-慢离子碰撞中的基本原子过程。在离子阻止能力最高、所有主要电子过程(电子俘获、损失和激发)达到最大的区域，此类碰撞完全缺乏测量和可靠的理论预测。它相当于原子物理学中真正的隐身之地。离子-离子碰撞是宇宙中普遍存在的现象之一，但在实验室中研究得最少。在控制良好的条件下跨越两个多电荷离子束一直是一项非常具有挑战性的任务，无论所考虑的物理领域是什么。法国和德国大型加速器设施(SPIRAL2和FIRE)即将提供高光学质量的强而稳定的离子束，这将最终允许将离子-离子碰撞研究扩展到上述方案。为了实现这一具有挑战性的目标，将建立一个独特的交叉束离子-离子实验装置，用于执行绝对截面测量。在需要克服的最严重的瓶颈中，我们可以强调目标对高能离子束的剥离阻力，控制交叉束流的重叠和掌握整体实验条件，以优化多符合事件探测。为了实现这一目标，我们将在以下方面开展专门的可行性研究：高强度束(脉冲和连续)的剥离器概念、离子探测系统以及对撞室中的束流控制和背景抑制。在这些研究的基础上，将设计、建造和进行第一次实验。在这个项目中，与两个德国和两个法国合作伙伴建立的合作特别适合于以非常特殊的技能和长期的合作传统来迎接这一挑战。

The main aim of this project is to investigate fundamental atomic processes in fast ion-slow ion collisions. Measurements and reliable theoretical predictions are completely lacking for such collisions in a regime in which ion stopping power is highest, and all the primary electronic processes (electron capture, loss and excitation) reach their maximum. It corresponds to a real terra incognita for atomic physics. Ion-ion collisions are one of the widespread phenomena in the universe but the least studied in laboratory. Crossing two multicharged ion beams, under well controlled conditions, has always been a very challenging task whatever the domain of physics under consideration. The forthcoming availability of intense and stable ion beams of high optical quality on French and German Large Scale Accelerator Facilities (SPIRAL2 and FAIR) will finally allow to extend ion-ion collisions studies into the above mentioned regime.In order to achieve this challenging goal, a unique crossed beam ion-ion experimental setup, to perform absolute cross section measurements, will be built. Among the most severe bottlenecks that should be overcome, we can stress the resistance of the target for stripping of the high energy ion beam; the control of the overlap of the crossed beams and the mastership of the overall experimental conditions to optimize the multi-coincidence event detection. In order to accomplish this, we will carry out dedicated feasibility studies on: stripper concept for high intensity beams (pulsed and continous), ion detection systems as well as beam control and background suppression in the collision chamber. Based on these studies the optimal experimental setup will be designed, built and first experiments performed.The collaboration built within this project with two German and two French partners is particularly well positioned to take up this challenge with very specific skills but also a long-standing tradition of collaboration.