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