CATHODE:

1

• CATHODE
• 36cm 20 um
• GEMs
• 70 um (10um copper, 50 um capton, 10um copper)
• Gain 320 V
• DISTANCE
• 1rst GEM-cathode 3cm
• in between GEMs 4mm
• cathode-right side 2.8 cm
• cathode-left side 4.2cm
• FIELD
• drift field 200 V/cm
• cathode 3960 V
• GARD-RING
• top 5cm high 2.5 cm long coated with 30um of
  Copper on the right side

2
Maxwell simulation of the potential
Right Potential variation for a 34 cm cathode,
the field isn't quite homogeneous on the GEMs
Left Potential variation for 36 cm cathode,
better homogenity. The next snapshots are only
with this model.
3
Equipotentail contour of the Potential
(Garfield)
4
Plot of the y over x components of the electric
field (Ey/Ex) Left 3D view Right plot of
Atan(Ey/Ex) vs the yaxis Field uniform
between -10 and 10 ie 20 cm, the GEMs are 24 cm
so 4 cm lost' on side effects...
5
Drift lines for a 1 GeV muon gas Ar CO2
(9010) Left Full view Right Zoom on the
bottom gard ring, side effects.
6
?
CATHODE 36 cm 10 um Al, 50 um myl, 1mm epoxy
(grille) MICROMEGAS active surface 34.55 cm
(perf cond.) 10 um support 352. mm 2.9 mm
epoxy
?
550
cathode
Mmegas
7
Side-mMegas distance
1 cm
2 cm
3 cm
8
Plot of the y over x components of the electric
field (Ey/Ex) Left 3D view Right plot of
Atan(Ey/Ex) vs the yaxis