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

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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.