High Resolution Study of p̄ — Atoms with a Focussing Crystal Spectrometer at LEAR

The performance of the low energy antiproton storage ring LEAR at CERN1,2 should give access to a new field of Nuclear physics studies. The low-eftergy antiproton beam allows to capture very efficiently antiprotons in bound atomic states probing a region around the nucleus which is much closer to the Nuclear surface than electronic or mesonic orbitals. The study of the X-ray transitions therefore yields information about the long range component of the hadronic interaction as well as about static properties of the antiproton3,4,5.The energies of interesting atomic K, L and M transitions in light systems range from 500 eV to 20 keV. The corresponding natural line widths have been estimated to become less than 50 meV, the relevant energy shifts being of the same order of magnitude6,7,8.