1. July 2003American Linear Collider Workshop Cornell U. Development of GEM-based Digital Hadron Calorimetry Andy White U.Texas at Arlington (for J.Yu, J.Li, M.Sosebee, S.Habib, V.Kaushik)

2. July 2003American Linear Collider Workshop Cornell U.  GEM operation/features  First UTA GEM prototype - structure, electronics – results: cosmics, source  Multichannel prototype  Digital hadronic module ideas  Funding, collaboration Outline

3. July 2003American Linear Collider Workshop Cornell U. Double GEM schematic From S.Bachmann et al. CERN-EP/2000-151 Create ionization Multiplication Signal induction

4. July 2003American Linear Collider Workshop Cornell U. From CERN-open-2000-344, A. Sharma GEM foil etching GEM field and multiplication 70  m 140  m

5. July 2003American Linear Collider Workshop Cornell U. GEM foil hole size

6. July 2003American Linear Collider Workshop Cornell U. GEM operations and features  Simple, robust  Stackable (single, double, triple)  Fast – electron signal  5ns  Relatively low voltage (~400V/foil)  Flexible – almost any anode design  Durable – no aging in extended tests  Gain 10 2 – 10 6

7. July 2003American Linear Collider Workshop Cornell U. Design for DHCAL using Triple GEM Ground to avoid cross-talk Embeded onboard readout

8. July 2003American Linear Collider Workshop Cornell U. First UTA GEM Prototype - Double GEM detector constructed using 10x10 cm 2 foils from CERN. - Single 1x2 cm 2 anode pad. - Charge preamp, then voltage amp. - Cosmic trigger, small counters, low rate! - Signal verification: no signal with (a) trigger counters displaced from anode pad, (b) air in GEM detector.

9. July 2003American Linear Collider Workshop Cornell U. UTA GEM-based Digital Calorimeter Prototype

10. July 2003American Linear Collider Workshop Cornell U. Anode pad layout 1x2 cm 2 pad

11. July 2003American Linear Collider Workshop Cornell U. UTA GEM prototype – high voltage

12. July 2003American Linear Collider Workshop Cornell U.

13. July 2003American Linear Collider Workshop Cornell U. GEM Prototype with preamp/voltage amp

14. July 2003American Linear Collider Workshop Cornell U. Amptek charge pre-amplifier

15. July 2003American Linear Collider Workshop Cornell U. GEM prototype – trigger counters

16. July 2003American Linear Collider Workshop Cornell U. Single cosmic event: upper = trigger, lower = preamp output UTA GEM Calorimeter prototype

17. July 2003American Linear Collider Workshop Cornell U. GEM cosmic signal distribution with Landau fit

18. July 2003American Linear Collider Workshop Cornell U. GEM prototype – source tests - Cs 137 source, ~1 MeV electrons - Wall of prototype thinned to allow electrons to reach ionization region of GEM, and use of thin trigger scintillators. - Rate much higher than cosmics! - Used secondary output of charge amplifier to generate ADC gate. - Study signals, noise, gain,…

19. July 2003American Linear Collider Workshop Cornell U. GEM prototype – source tests Source signal Noise

20. July 2003American Linear Collider Workshop Cornell U. Landau Distribution from Cs 137 Source Signal Amplitude (mV)

21. July 2003American Linear Collider Workshop Cornell U. GEM/MIP Signal Size Computation -Double GEM – applied 419V/stage -Total Ionization (C): ~93 i.p./cm  48 e - /MIP (5mm gap) -Double GEM Intrinsic Gain: G -Charge preamp sensitivity (G C ) : 0.25  V/e - -Voltage amp. X10 (G V ) -Output signal = C x G x G C x G V -Observed ~370mV signal (mean of Landau)  G = 3100 ± 20% (need better amplifier calibration)

22. July 2003American Linear Collider Workshop Cornell U. CERN GDD group measurements Measured UTA GEM Gain UTA Prototype

23. July 2003American Linear Collider Workshop Cornell U. 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. - Use e.g. HELIX chip for readout. - Anode board built, prototype being reworked.

24. July 2003American Linear Collider Workshop Cornell U. Nine Cell GEM Prototype Readout

25. July 2003American Linear Collider Workshop Cornell U. GEM module ideas - Start from basic TESLA detector layout - Try simple design with GEM “drawers” slid into slots in absorber (formed from plates and spacers). - GEM layer ~6mm, readout layer ?mm. - Readout – amplifier, discriminator, register per channel close to anode pad. Multilayer board with multiple ground planes. - Working on existence proof of readout, services, module boundaries, supports, …

26. July 2003American Linear Collider Workshop Cornell U.

27. July 2003American Linear Collider Workshop Cornell U.

28. July 2003American Linear Collider Workshop Cornell U. TESLA – HCAL Layout

29. July 2003American Linear Collider Workshop Cornell U. DHCAL/GEM Module concepts Use half-size modules w.r.t. TESLA design

30. July 2003American Linear Collider Workshop Cornell U. Design concept for sensitive layer 3mm ionization layer

31. July 2003American Linear Collider Workshop Cornell U. 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

32. July 2003American Linear Collider Workshop Cornell U. DHCAL/GEM Module concepts Bottom view Side view End view

33. July 2003American Linear Collider Workshop Cornell U. DHCAL/GEM Module concepts GEM layer slides into gap between absorber sheets

34. July 2003American Linear Collider Workshop Cornell U. GEM operation in magnetic field - Electrons drift along E-field lines which are ~radial in the overall detector frame. - However, B-field exists in orthogonal direction. - Forces on electron from E and B ~ equal -> so…expect ~45 deg. drift. B drift E

35. July 2003American Linear Collider Workshop Cornell U. Funding DoE ADR funding for year 1 completed -> Prototypes working, many simulation results (see talk by Jae Yu at this meeting) Request for two more subsequent years of ADR funding –First year of the two funded for ½ student and ½ engineer/postdoc Equipment funds through ADR + LCRD –Allows us to contemplate construction of a larger size GEM prototype

36. July 2003American Linear Collider Workshop Cornell U. Collaboration  Discussions with Fermilab (Physics dept.) re support for development of: - readout electronics (amplifier, discriminator, …) - electronics “layer” - GEM calorimeter stack for test beam  Agreement (June ’03) to proceed.

37. July 2003American Linear Collider Workshop Cornell U. Conclusions  Built and operated first prototype  Cosmic and source results – gain OK  Multi-channel prototype being built  First ideas on module design  Funding in place for another year  Collaboration with Fermilab agreed.