Antiproton charge radius

The upcoming operation of the extra low energy antiprotons ring at CERN, the upgrade of the antiproton decelerator (AD), and the installation in the AD hall of an intense slow positron beam with an expected flux of 108 e+/s will open the possibility for new experiments with antihydrogen (H¯). Here we propose a scheme to measure the Lamb shift of H¯. For four months of data taking, we anticipate an uncertainty of 100 ppm. This will provide a test of CPT and the first determination of the antiproton charge radius at the level of 10%.