Manipulation of ultraslow antiprotons and first application to atomic collisions

R. Funakoshi, Kunihiro Suzuki, Christoph Scheidenberger +49 more

H. A. Torii, Y. Nagata, Hiroshi Toyoda +4 more

N. Kuroda, Y. Nagata, H. A. Torii +11 more

We report here the radial compression of a large number of antiprotons under ultrahigh vacuum conditions by applying a rotating electric field. The radial compression is a key technique for production of ultraslow antiproton beam extracting from an electromagnetic traps. Such beam will be applicable to synthesizing antiprotonic atoms and antihydrogen atoms.

Brett D. Esry, H. R. Sadeghpour

The collision of an antiproton and a hydrogen atom at ultralow energies is described in hyperspherical coordinates. An adiabatic approximation leads to potential-energy curves that can be used to describe the dynamics of capture in the $\overline{p}\ensuremath{-}\mathrm{H}(1s)$ collision. A unified formulation of the collision and capture processes leading to formation of $p\overline{p}$ bound states emerges. Both $\mathrm{Pn}{(\mathrm{nl})\ensuremath{-}e}^{\ensuremath{-}}$ ``atomic-type'' and $\overline{p}\ensuremath{-}\mathrm{H}{(n}^{\ensuremath{'}}{l}^{\ensuremath{'}})$ ``molecular-type'' states are represented. These potential curves are calculated to more than 10 000 protonium Bohr radii, where low-energy antiprotons are stopped in collisions with hydrogen atoms. Elastic and inelastic partial and total protonium formation cross sections in the mass-scaled $\overline{p}$-H system are calculated. The existence of protonium negative (or positive) ion in its ground and excited states is discussed.

J. Révai, N. V. Shevchenko

Françoise Masnou-Seeuws