ULTRACOLD ANTIPROTONS AT LEAR

The unique capability of the Low Energy Antiproton Ring LEAR to produce a low energy antiproton beam opened the possibility to perform high-precision tests of symmetry principles on baryon-antibaryon systems. The excellent beam quality made it possible for the first time to store antiprotons in a Penning trap and to cool them further to energies below 10 meV. A high-precision mass measurement with trapping techniques was performed on the proton-antiproton system, increasing the accuracy of this fundamental mass ratio to a limit of DELTA-m/m = +/- 4.2 x 10(-8). The success of the trapping techniques developed along this mass measurement may open a completely new generation of experiments by forming antihydrogen in a double-structure Penning trap holding antiprotons and positrons at the same time. With the formation of antihydrogen, the extremely difficult comparison of the gravitational forces on matter-antimatter systems and even high-precision laser spectroscopy on antihydrogen may become feasible.