A New Technology for Fast Two-Dimensional Detection of Proton Therapy Beams

Figure 1

The Micromegas board. The five readout anodes can be seen in the center and are numbered. The woven micromesh is held above the readout anodes by photo-etched Kapton standoffs (visible as small points covering the anode plane) that maintain a uniform 128 μm gap. The center channel is 5 cm in diameter. Also visible is the insulating ring, O-ring for gas seal, high voltage lead (lower right), and gas feed pipe (upper left).