Tracked pellets — a way to improve the efficiency of charmonium studies

We investigate the possibility of tracking individual hydrogen micro-spheres from an internal pellet target. Such a method aims to provide the primary vertex of a reaction to within about 100 μ m , without utilizing any detector response. Apart from background considerations the knowledge of the reaction vertex may be essential for the reconstruction of many physics channels. This is in particular true for the study of the Ψ ( 3770 ) decay into D-mesons planned at the PANDA detector at the future FAIR facility. Here, the reconstruction of displaced vertices is especially difficult since neutral particles are involved. Studies with a pellet target at The Svedberg Laboratory, Uppsala, show the technical feasibility of a tracking system utilizing fast CCD line-scan cameras. Simulations for the reaction p ¯ p → Ψ ( 3770 ) → D + D - prove the large impact such a system would have on the data taking and reconstruction at PANDA.