Production of Low-Energy Antiprotons

The production, collection and deceleration of antiprotons is reviewed with the aim of establishing guidelines for the design of a simple yet efficient source of stopped antiprotons. A high-energy (20-100 GeV) high-intensity (~ 1013 protons/pulse) proton accelerator is needed to produce antiprotons in copious numbers. A 'passive' conversion-target consisting of a thin iridium rod embedded in graphite, and a magnetic-horn type lens to collect the antiproton flux from the target represent a good compromise between yield and reliability. To transport the flux to low energy a large-acceptance cooling and deceleration ring working up to an energy equal to one-eighth to one-tenth of the primary proton energy is required. Stochastic cooling (at high energy) and electron cooling (at lower energy) are indispensable for providing low-energy beams of useful density.