In experiments with a very low event rate, background is always a factor to be considered and hopefully to be reduced to get a clear signal. An example of such an experiment is the CAST experiment which searches for axions, possible candidates for dark matter. This thesis gives an overview on the development of a new Framestore pn-CCD detector to fit the requirements of such experiments. General material composition and the working principle of a Graded-Z shielding concept for such a detector are explained. Exemplary simulations of such a shield and first test results for the detector’s vacuum and cooling systems are presented as well.