Andy White

1

Update on GEM-DHCAL work at UTA
Andy White U.Texas at Arlington (for J.Yu, J.Li,
M.Sosebee, S.Habib, V.Kaushik) 06/21/04.
2
Development of large-scale GEM layer
Recent hardware activities have focused on
techniques for assembly of GEM modules.
Successful assembly of several mechanical
prototypes using kapton instead of actual GEM
foils. Now ready to move to full-scale working
layers.
3
Development of GEM sensitive layer
Absorber strong back
Gas inlet/outlet (example)
Cathode layer
3 mm
Non-porous, double-sided adhesive strips
1 mm
1 mm
9-layer readout pc-board
Anode(pad) layer
Fishing-line spacer schematic
(NOT TO SCALE)
GEM foils
4
(No Transcript)
5
Development of large-scale GEM layer

• Original plans were to use existing roll of 3M
  10cm x 10cm foils
• However, the roll no longer exists!
• Discussions on new run to produce what we
  actually need.
• Several other customers for GEM foils for
  various studies (La Tech., U.Washington,
  IHEP-Beijing,)

6
3M GEM foil production

• Aim for 3 GEM foil strips/layer for 1m3
  prototype.
• Need subdivision of GEMs into separate voltage
  segments minimal no-copper gap.
• Other issues
• - use of Mylar for masks -gt hole
  slewing
• gt glass phototool better but more
  costly
• - pattern repetition/kapton gap for
  gripping edge
• - New layout (with 15cm x 15cm subunits -gt U.W.
  etc.)

7
Recent 3M GEM foil profile
Approximate size of large-scale drawer
16 inches
500 ft roll
12 inch wide active width
10 x 10 cm2
8
3M GEM foil new layout
9
3M GEM foil new layout (detail)
10
3M GEM foil production

• Quotation this week
• Refine layoutdevelop cost sharing
• Specify QC at 3M and UTA
• Delivery?

11
Understanding crosstalk for GEMs
Recent study by Jia Li/UTA

• What we see/measure in a small prototype
• Noise reduction
• Understanding what we see from use of live
  simulation using a pulse generator.

12
Typical crosstalk signal (prototype)
13
Crosstalk simulation (pulse generator)
14
Crosstalk derives from edges
15
Effect of rise time
16
Bigger pads larger effect
BigPad
17
and vice-versa
SmallPad
18
Effect of gap between adjacent pads
Large Gap
19
Effect of gap between adjacent pads
Small Gap
20
Usual situation no crosstalk visible
21
Rare example of large crosstalk
22
Effect of sharing signal between adjacent pads
Trigger252 Thr.110mV, V2000V.
23
Conclusions

• ? Progress on large scale GEM foil production for
  test beam prototype
• Crosstalk studied and origins/effects understood
• (Update on DHCAL simulations at next meeting)