Production and study of antideuterium with the GBAR beamline

The potential of circulating antideuterons (\(\mathrm {\overline{d}}\)) in the AD/ELENA facility at CERN is under active investigation. Approximately 100 \(\mathrm {\overline{d}}\) per bunch could be delivered as a \({100\,\textrm{keV}}\) beam based on measured cross-sections. These \(\mathrm {\overline{d}}\) could be further decelerated to \({12\,\textrm{keV}}\) using the GBAR scheme, enabling the synthesis of antideuterium (\(\mathrm {\overline{D}}\)) via charge exchange with positronium, a technique successfully demonstrated with \({6\,\textrm{keV}}\) antiprotons for antihydrogen production. The AD/ELENA facility is currently studying the possibility of increasing the \(\mathrm {\overline{d}}\) rate using an optimized new target geometry. Assuming this is feasible, we propose further enhancing the anti-atom production by using laser-excited positronium in the 2P state within a cavity, which is expected to increase the \(\mathrm {\overline{D}}(2S)\) production cross-section by almost an order of magnitude for \(\mathrm {\overline{d}}\) with \({2\,\textrm{keV}}\) energy. We present the projected precision for measuring the antideuterium Lamb shift and extracting the antideuteron charge radius, as a function of the beam flux.

\(\mathrm {\overline{D}}\) production rate assuming 1e9 ortho-\(\textrm{Ps}\) from a flat target interact with \(\mathrm {\overline{d}}\) with \({12\,\mathrm{\text {k}\text {eV}}}\) (blue) or inside a cavity (orange). Within the cavity, \(\textrm{Ps}\) can be excited to the 2P state, further increasing the charge exchange cross-section for \(\mathrm {\overline{d}}\) at \({2\,\mathrm{\text {k}\text {eV}}}\) (green). Cross-sections are calculated using the Convergent Close Coupling (CCC, solid) method [36] and the Coulomb-Born approximation (CBA, dashed) [37]