CERN Accelerating science

Polyimide etching using different chemistries.

GEM holes obtained from single mask photolithography. The left picture shows the top copper electrode, where the rim is visible, while the right picture shows the bottom layer. The central picture is a hole cross-section.

GEM holes obtained from single mask photolithography, with electrochemical protection and polyimide post-etching. From left to right: top electrode, cross-section, bottom electrode.

Copper spectrum obtained from a double GEM stack based on single mask GEMs with electrochemical protection.

Normalized gas gain of a single mask double GEM stack as a function of time.

Microscope picture of the seam and rate scan with collimated X-ray beam.

Simulated equipotential lines and field lines. The hole diameters are 95 $\mu$m in the top and 55 $\mu$m in the bottom layer for the left part, and 55 $\mu$m in both layers for the right part of the figure.

Electron end point distributions. The horizontal axis represents the geometry (hole diameter on the top and on the bottom, in micron), while the vertical axis is the percentage of electrons ending up on each GEM layer.