1. Updates on the Micromegas + GEM prototype
Fri, 21st August 2009 – CERN
Marco Villa
Athanasios Chouliaras
Sinem Salva

2. Detector schematic GEM specifications: Micromegas specifications:
Drift mesh
10x10 cm2
3.25 mm
Standard GEM foil
2.2 mm
Micromegas mesh
0.128 mm
Anode
Micromegas specifications:
45 µm mesh pitch
18 µm mesh wire diameter
2.5 cm pillar pitch
300 µm pillar diameter
GEM specifications:
hexagonal hole geometry
biconical holes
140 µm hole pitch
70 µm hole outer diameter
50 µm inner diameter
50 µm kapton thickness
5 µm copper thickness

3. Energy resolution Gas mixture Ar/CF4 90/10 drift field 0.62 kV/cm
GEM voltage 325 V
transfer field 1.25 kV/cm

4. Gain Gas mixture Ar/CF4 90/10 drift field 0.62 kV/cm GEM voltage 325 V
transfer field 1.25 kV/cm

5. Alphas current Gas mixture Ar/CF4 90/10 drift field 0.62 kV/cm
GEM voltage 325 V
transfer field 1.25 kV/cm

6. New detector schematic
Drift mesh
10x10 cm2
3.3 mm
Micromegas mesh
0.128 mm
Anode
Micromegas specifications:
45 µm mesh pitch
18 µm mesh wire diameter
2.5 cm pillar pitch
300 µm pillar diameter

7. Energy resolution
Gas mixture Ar/CF4 90/10
drift field 1.25 kV/cm