1. Andy White U.Texas at Arlington (for J.Yu, C.Han, J.Li, D.Jenkins, J.Smith, K.Parmer, A.Nozawa, V.Kaushik) 10/18/04 IEEE/NSS Digital Hadron Calorimetry for the Linear Collider Using Gas Electron Multiplier Technology

2. Linear Collider Physics  A program of e + e - discovery and precision physics at 1TeV  Understanding the Electroweak sector - Origin of mass – Higgs physics…couplings - EW Symmetry breaking – Supersymmetry?  Precision studies of the massive top quark  Search for New Physics: W’, Z’, leptoquarks, …. …, extra dimensions  Much of this physics program requires high precision measurements of jet energies and jet-jet invariant masses - > hence the need for a new approach to hadronic calorimetry.

3. Digital hadron calorimetry - Need for high resolution energy measurements of jets - example: separation of W, Z in hadronic mode - Three components of jet energy in calorimeter: 1) electromagnetic – measured well in e.m. calorimeter 2) charged hadrons – track(s) + cluster(s) in hadron and e.m. calorimeter 3) neutral hadrons – cluster(s) in hadron and e.m. calorimeter - Use momentum measurement of charged hadrons in magnetic field, track them to energy clusters in hadron calorimeter, remove associated energy – remainder is neutral energy (“Energy flow algorithm”)  Must track charged hadrons in calorimeter !

4. Simulation of W, Z reconstructed masses in hadronic mode. (from CALICE studies, H.Videau, shown at ALCPG/Cornell: M. Schumacher) Importance of good jet energy resolution 60%/  E 30%/  E

6. Digital hadron calorimetry (2) A new approach: - use small cells (~1cm x 1cm) - cell is either ON or OFF. - high granularity allows charged track following - good correlation between energy and number of cells hit. - requires development of “Particle Flow Algorithm” to associate energy clusters/tracks.

7. Digital calorimetry – counting cells

8. Digital Calorimeter Implementation -There are a number of possible ways to implement digital hadron calorimetry: - small scintillator tiles/SiPM (> 3cm x 3cm) - resistive plate chambers (long term stability? rate?) - wire chamber/pads? OR a new approach: Gas electron multiplier/1cm x 1cm pads - easy to implement small cells - fast - robust

9. From CERN-open-2000-344, A. Sharma GEM foil/operation GEM field and multiplication 70  m 140  m Invented by Fabio Sauli/CERN

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

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

12. Nine Cell GEM Prototype Readout

13. Double-GEM prototype results: Gas mix

15. Typical crosstalk signal (prototype)

16. Crosstalk studies

17. Sr 90 (beta) source

18. Next steps for prototyping - Determined by availability of GEM foils of larger size. - Likely short-term availability is for 305mmx305mm foils from 3M Corporation. - Plan is to build a cosmic (vertical) stack of 5- 6 layers using the 305mmx305mm foils. - Use Fermilab 32-channel cards until ASIC available. - Restrict readout to 10x10 channels/layer while using the Fermilab cards.

19. (10 x 10) – 4 active area Trace edge connector -> Fermilab 32 ch board 305mm x 305mm layer

20. GEM strip from 3M roll 305mm Development of large-scale GEM layer for final test beam stack ~1m Test beam stack will be 1m 3, with 40 active layers each ~8mm thick between steel absorber plates.

21. Development of GEM sensitive layer 9-layer readout pc-board 3 mm 1 mm Non-porous, double-sided adhesive strips GEM foils Gas inlet/outlet (example) Cathode layer Absorber strong back Fishing-line spacer schematic Anode(pad) layer (NOT TO SCALE)

22. 3mm side walls and spacers installed

23. T2K large GEM foil design (Close to COMPASS(CERN) foil design)

25. 3M GEM foil – new layout

26. Readout Electronics Working with ANL/RPC Group on common front-end readout ASIC: - Selectable gain: high for GEM, low for RPC. - Circuit evaluation using SPICE at UTA - Common PC board/anode pad layer with RPC - Digital design ~complete, Analog design following BTeV chip. DHCAL specific final development in early 2005.

27. Personnel New collaborators on GEM/DHCAL: - University of Washington, T. Zhou - Tsinghua University, Beijing, China, Prof. Jin Li,

28. Conclusions  Development of a new type of digital calorimeter  Prototype development sources/new gas mixtures.  Mechanical tests for large area active layers  Exploring using 305mmx 305mm foils in multi-layer cosmic stack as intermediate step to test beam.  Ongoing discussions with 3M + 4 other groups on foil development.  Working towards a test beam stack…for 2006 beam tests at Fermilab