Targets for the electron–positron pair spectrometer HADES

For experiments performed with the HADES spectrometer (High Acceptance Di-Electron Spectrometer) [1] at GSI a very extraordinary target set-up is required. Since these experiments are strongly background-dominated the alignment and mounting of the targets is crucial for the identification of the electron–positron pairs searched for as a decay product of the vector mesons. The positioning of the numerous target discs has to be done with accuracy better than ±200 μm and with a minimum of material around the targets.We describe the target design, the production of the different components and the mounting methods. Finally, an outlook on future target designs and ideas is given.