Fig. 1

a A schematic of the Ps production region, detectors, and waveguide. b A cross-section of the MgO coated WR-112 waveguide in the xy plane. c A 3-D schematic of the target, grid, and microwave guide. The target (T) and grid (G) electrodes were mounted on a separate manipulator that could be moved off axis to allow direct imaging of the positron beam after it had passed through the waveguide.The waveguide dimensions are in mm