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Production of Gaseous Detector Elements

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97: first GEM 100 x 100mm with gain of 10000. ... Photolitho. Glue to substrate. S of X = S of Y. EST-DEM. R. De Oliveira. 20 Dec., 04 ... – PowerPoint PPT presentation

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Title: Production of Gaseous Detector Elements


1
Production of Gaseous Detector Elements
  • History of Gas Detectors in Workshop
  • Fabrication of GEM Detectors
  • Fabrication of Micro-megas
  • Readout Circuits
  • Other Detectors

2
History of Gas Detectors in Workshop
  • 96 first GEM about 50 x 50mm with a gain of 10.
  • 97 first GEM 100 x 100mm with gain of 10000.
  • 98 - 99 first GEM 400 x 400mm 1D and 2D
    readouts first micro-groove and micro-well
    detectors.
  • 00 first 3D GEM readout first 1D readout for
    Micro-megas in COMPASS.
  • 01 first PIXEL GEM readout first 2D
    Micro-megas readout.
  • 03 first PIXEL Micro-megas readout.

3
Fabrication of GEM Detector
  • Theory of Operation
  • Cross-section of GEM
  • Manufacturing Process
  • Examples
  • GEM Capabilities
  • How to Buy a GEM?

Around 500 GEMs produced per year in CERN.
4
Theory of Operation
Particle trajectory
Electrode -3000V
1 x e-
Gas
GEM
8000 x e-
Readout board 2D 0V
Top View
Lines Y
Lines X
5
Cross-section of GEM
6
Manufacturing Process
Raw Material
Vacuum deposited copper on polyimide
Applying Resist
Image Transfer
Patterning Resist
UV Exposure Development
Copper Etching
Resist Stipping
Polyimide Etching and Cleaning
7
Manufacturing Process
  • Image transfer with film pocket
  • Copper Etching in a Drawer Machine

8
Manufacturing Process
Defect
Good
Perfect
  • Polyimide Etching in a Static Bath with
    Temperature Control
  • Hole Shape Control

9
Manufacturing Process
  • Electrode patterning
  • Cleaning
  • Electrical Test
  • (Less than 10nA at 600V
  • with humidity below 35)

10
Examples
40 cm diameter
28 x 28 mm active area
100 x 100 mm standard Ni/Au
50 x 50 mm standard copper
11
Examples
COMPASS Experiment (100 GEMs) segmented
Test for CMS, 45 cm long
HERA-B Experiment (300 GEMs)
12
Examples
Fine segmentation test with printed polarization
resistors
13
GEM Capabilities
  • Gem size up to 450 x 450 mm2
  • Hole diameter from 25µm and up
  • Thickness of dielectric 25, 50 or 100µm
  • Platings passivated copper, Ni/Au, Ni or Au
  • Spacers from 1 to 3mm in multi GEM detectors

300µm width, 2mm height
Material not in stock
14
How to Buy a GEM?
  • http//www.cern.ch/dem/products/gem
  • standard products
  • 100 x 100 mm active area
  • 50 x 50 mm active area
  • with or without frame
  • passivated copper or Ni/Au
  • non-standard products please contact the
    workshop

15
Fabrication of Micro-megas
  • MicroMegas
  • Theory of Operation
  • Manufacturing Process
  • Possibilities
  • Examples
  • Bulk MicroMegas
  • Manufacturing Process
  • Possibilities
  • Examples

16
MicroMegas Theory of Operation
Particle trajectory
Electrode -3000 V
e-
Gas
Frame
Grill
Spacer
Readout circuit 0 V
17
MicroMegas Manufacturing Process
Raw Material
Image Transfer Copper Etching
Frame Gluing
Polyimide Etching Cleaning
18
MicroMegas Possibilities
  • Size of the grill
  • max 40cm diameter
  • Bigger sizes under development
  • Pattern mini 500 mesh, 1000 under study
  • Metals copper, nickel, titanium
  • Spacers
  • on the grill 25 or 50µm thick (polyimide)
  • on the readout from 50µm to 0.5mm (modified
    epoxy)

19
MicroMegas Examples
CAST Experiment (special Plexiglas frame)
Zoom on polyimide dots on the grill
KABES Experiment
20
Bulk MicroMegas Manufacturing Process
21
Bulk MicroMegas Possibilities
  • Size of the bulk
  • max 40cm x 40cm
  • Pattern mini 600 mesh
  • Metals stainless steel
  • Spacers
  • 75µm height (150µm, 225µm), modified epoxy
  • Multi grid systems (under study)

22
Bulk MicroMegas Examples
23
Readout Circuits
1 Direction
2 Directions
3 Directions 3D
Pixel
24
2D
Polyimide 50 um
Image the micro-vias
Chemical drilling
Metallization 15 um
Photolitho
S of X S of Y
Glue to substrate
25
Example of Single Side (1D)
Close-up of readout board
Readout board for NA48 Experiment
26
Example of 2D Readout Circuit
Readout active area
2D readout board glued on low intrinsic radiation
Plexiglas substrate
27
Example of 3D
Readout for TPC with
backside connection 30cm diameter
18000 pads
28
Pixel
Close-up view Pad 1mm Pitch 1.05mm
1024 pads on a diameter of 35mm
Smallest pad produced 250µm Pitch 300µm
29
Readout Possibilities
  • Supporting materials
  • FR4
  • Metals
  • Flexible
  • without substrate
  • Low mass
  • Carbon composite
  • Low intrinsic radiation
  • Plexiglas
  • Kevlar Composite

30
Other Detectors
  • Micro-groove
  • Micro-well

R. Bellazzini group, INFN-Pisa, and University
of Pisa
31
Micro-groove
Close-up view
12 x 10cm groove detector
Bottom lines
Top lines
32
Micro-well
Close-up view
3 x 3 cm well detector
Bottom lines
Top electrode
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