Search for Lambda-Lambda hyperuclei using antiprotons in PANDA

The Double Hypernuclei are the only systems that allow to study the hyperonhyperon interaction because the hyperon-hyperon scattering experiments are at present impossible. Experimental data are still very scarce, due to the difficulty of producing the doubly strange hyperon −, from which a double hypernucleus is formed. The formation of such a hypernucleus proceeds through a multiple-step process and the measurement of the relevant parameters (e.g. energy separation and decay branching ratios) requires high statistics. The PANDA Collaboration planned to exploit the intense beam of the HESR machine at the future facility FAIR to produce − hyperons from antiproton annihilation in nuclei. A 12C target will be inserted inside the ring: the sizes of the target and the beam spot overlap play a crucial role to avoid serious damage of beam and detectors. The status of the art of the present data, the design of the optimized target and the tests on the prototype will be presented.