1. UPDATE ON GEM/DHCAL DEVELOPMENT AT UTA Andy White U.Texas at Arlington (for J.Yu, J.Li, M.Sosebee, S.Habib, V.Kaushik) 9/15/03

2. Recent developments  Moving to multi-channel prototypes  GEM foil production  Electronics – prototypes  Module design concepts

3. Double GEM schematic From S.Bachmann et al. CERN-EP/2000-151 Create ionization Multiplication Signal induction

4. Design for DHCAL using Triple GEM Ground to avoid cross-talk Embeded onboard readout

5. Multichannel prototype - Next step: a 3 x 3 array of 1 cm 2 pads. - Allows one central pad with neighbors for cross-talk tests. - Use a single layer board for simplicity. - Anode board built, prototype reworked. - First results.

6. Nine Cell GEM Prototype Readout

7. Landau Distribution from Cs 137 Source Signal Amplitude (mV)

8. Readout electronics for DHCAL/GEM - Single channel electronics for first tests (high gain charge preamp + x10 voltage amp.) - Useful for initial development, but not cost effective for larger scale, multi-channel prototypes.

9. GEM Prototype with preamp/voltage amp

10. Amptek charge pre-amplifier

11. Readout electronics for DHCAL/GEM - Discussions with Fermilab/PPD (Ray Yarema) - Short-term use of electronics developed for silicon readout. (T.Zimmerman) - 32 channel boards. Now at UTA. - Gain within factor of 3 of present single channel system. - Investigating DHCAL/GEM specific design - Coherence with DHCAL/RPC – VME/daughter?

12. Fermilab preamp for multi-channel tests

13. GEM Foil Production - Original production at CERN – but slow, low volume, manpower intensive and expensive. - Interest in U.S. domestic foil production by LC tracking developers and GEM/DHCAL. - 3M Corporation (Microinterconnect Systems Division), Austin, Texas has tried additive and subtractive approaches. - Foil production on 16 inch wide, 500 feet long roll.

14. Our Motivation: Micro Pattern Gas Detectors (MPGD) in Particle & Astro-Particle Physics TPC readout for LC (GEM or MICROMEGAS) Tracking device at SLHC or VLHC Low-background applications (e.g. coherent neutrino scattering) & WIMP searches Chicago-Purdue-3M P.S. Barbeau J.I. Collar J. Miyamoto I.P.J. Shipsey + DHCAL/GEM developments + Medical imaging potential + ? GEM Foil Production

15. 3M Microinterconnect Systems Division Reel-to-reel process, rolls of 16”’x16” templates of detachable GEMs in any pattern. Optional processes possible. First batch of 1,980 GEMs recently produced. Low cost per unit! (~2 USD/GEM not counting R&D) Two fabrication techniques (additive, substractive) tested. Single roll of ~1,000 GEMS Reel to reel flex circuit manufacture in clean room conditions hep-ex/0304013 Mass Production is based on a 3M Proprietary Flex Circuit Manufacturing Technique

16. Subtractive (etching) (similar to CERN made GEMs) Additive Cu added to patterned photo resist on Kapton Two fabrication techniques Subtractive Additive

17. 1. Subtractive: Clean hole structure, microcrystals, a small part of the batch have problems with adhesion of Cu on Kapton 2. Additive: Some holes not perfectly round  create hole to hole gain variation, a small part of the batch have problems with adhesion of Cu on Kapton hep-ex/0304013 Cu microcrystal Additive method needs improvement to be useful 3M Process Quality

18. Chicago Purdue 3M GEM SEM Courtesy Fabio Sauli Subtractive 3M Mass Produced GEM

19. Chicago Purdue 3M GEM SEM Courtesy Fabio Sauli Hole Profile

20. GEM Performance Typical 55 Fe spectrum uncolllimated source. Ar + 5% CH4 Lower GEM electrode.  E/E = 16% typical energy resolution as good as 14% observed. hep-ex/0304013 So far characterization focused on subtractive GEMs 3M GEM and CERN GEM Have comparable  E/E = 16% 3M GEm  E/E = 16% CERN GEM  E/E = 18% http://gdd.web.cern.ch/GDD/

21. Ar/DME 9:1 Ar/CO2 7:3 Gain measured on lower GEM electrode Gain measured on PCB below GEM Gains of 5,000 in Ar/CO2 7:3 & Ar/DME 9:1 Gain almost identical to CERN made GEMS in same gas x x CERN GEM * (*) S. Bachmann et al. NIM A479 (2002) 294 Gas Gain hep-ex/0304013 CERN

22. GEM Foil Production - Latest production 2 x 2 pattern of 10x10 cm 2 foils. - Use for DHCAL small prototypes and module development - 3M can make any pattern within the roll parameters (~$2K for artwork)

23. TESLA – HCAL Layout Development of module concepts

24. DHCAL/GEM Module concepts Use half-size modules w.r.t. TESLA design

25. DHCAL/GEM Module concepts Bottom view Side view End view

26. DHCAL/GEM Module concepts GEM layer slides into gap between absorber sheets

27. DHCAL-GEM Layer structure - GEM layer -> 6mm - Electronics layer ~3mm - Absorber thickness 16mm x 40 layers -> ~ 4 interaction lengths for HCAL - 10x10 mm 2 cell size -> ~1.5 x 10 7 channels for DHCAL-GEM

28. DHCAL/GEM active layer - Basic layer structure is clear - Practical issues: - minimizing thickness, readout layer, ground plane(s) ?? - stretching foils, foil separators, wall thickness - gas in/outlets, electrical services

29. DHCAL/GEM active layer - Exploring using the absorber steel gap to provide active layer rigidity. - Build jig to construct active layer with stretch foil layers, thin side walls. - Test transfer/sliding of non-rigid active layer into steel gap. - Start with available width foils from 3M

30. Design concept for sensitive layer 3mm ionization layer

31. CONCLUSIONS  Further prototype development  Exploring electronics solutions with Fermilab/PPD  Availability of U.S. domestic GEM foils  Investigating active layer construction techniques