Open-endcap Penning traps for high precision experiments

Cylindrical Penning traps with open-endcap electrodes are compared with the hyperbolic traps which are currently used for high precision experiments. Cylindrical traps are easier to construct and allow free access to the center of the trap for particle loading, laser beams, or microwaves. The trapping potential can be tuned while particles are inside the trap to improve harmonicity. Special geometries are noted which allow anharmonicities to be tuned out without affecting the trap well depth, and the effects of trap imperfections and gaps between the electrodes are discussed. Such traps will be used for measuring the antiproton mass, for colling of trapped antiprotons, and possibly for producing antihydrogen.