Precision measurement of the proton charge radius with elastic electron scattering

A precise measurement of the proton charge radius is an old, but still open problem. Interest is renewed by extremely precise Lamb Shift measurements Requiring higher-order QED corrections for their interpretation depending on the proton charge radius. Existing measurements show a considerable scattering of results. A new precision experiment using elastic electron scattering is now in preparation at the S-DALINAC, where backscattered protons instead of the electrons will be measured. This new method has many advantages. For example, one can measure range of momentum transfers with a single setup, thereby avoiding normalization problems. Recent test measurements demonstrate the feasibility of such a kind of experiment, but several problems need to be solved first. Preliminary results and conclusions are discussed