Low Energy Antiproton Ring

The upcoming Antiproton Decelerator (AD) [1] at CERN allows the formation and precision spectroscopy of antiprotonic atoms. Among the three approved experiments, the ASACUSA collaboration [2] will as part of its program continue experiments with antiprotonic helium that were previously performed by the PS205 collaboration [3] at the now closed Low Energy Antiproton Ring (LEAR) of CERN. Antiprotonic helium consisting of an alpha particle, an antiproton, and an electron (He++ —p — = pHe+), was found to have lifetimes in the... 

A first version of the experimental set-up was successfully used at CERN on LEAR (Low Energy Antiproton Ring), to study 3d -> 2p transitions in antiprotonic hydrogen and deuterium [4], to obtain information on the antiproton-nucleon interaction. It was also used to measure the mass of the charged pion for the first time in a low density gas, using transitions between circular levels of pionic nitrogen [5], using copper Ka transitions as X-ray standards. 

---