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Status of DHCAL using GEM

Status of DHCAL using GEM. Introduction Digital Hadron Calorimeter GEM in the sensitive gap Status of GEM DHCAL prototype Simulation study status Summary. J. Yu Univ. of Texas at Arlington LCWS 2002, Aug. 26 – 30, 2002 Jeju Island, Korea.

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Status of DHCAL using GEM

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  1. Status of DHCAL using GEM • Introduction • Digital Hadron Calorimeter • GEM in the sensitive gap • Status of GEM DHCAL prototype • Simulation study status • Summary J. Yu Univ. of Texas at Arlington LCWS 2002, Aug. 26 – 30, 2002 Jeju Island, Korea (on behalf of the UTA team: A. Brandt, K. De, S. Habib, V. Kaushik, J. Li, M. Sosebee, A. White)

  2. Introduction • LC physics topics require higher jet energy resolution • Distinguish W from Z in two jet final states • s/E~30%/sqrt(E) • Excellent jet angular resolution • Energy flow algorithm is one of the solutions • Replace charged track energy with momentum measured in the tracking system • Requires efficient removal of associated energy cluster • Higher calorimeter granularity • Use calorimeter only for neutral particle energies • Large number of readout channel might drive up the cost for analogue style energy measurement  Digital hadron calorimeter • Tracking calorimeter with high gain sensitive gap Jae Yu: GEM Based DHCAL

  3. Goals for DHCAL Development • Develop digital hadron calorimetry for use with EFA • Develop GEM cell(s) and prototype • Develop module and stack design • Simulate GEM behavior • Implement GEM readout structure into simulation • Develop energy flow and calorimeter tracking algorithms • Estimate cost for large scale GEM readout layer Jae Yu: GEM Based DHCAL

  4. DHCAL General Requirements • Thin and sensitive readout layer for compact design • 1 or 2 level hit recording for EFA use • On-board amplification, digitization and discrimination for readout, minimizing noise and cross-talk • Flexible design for easy implementation of arbitrary cell size for upgrade • Minimal intrusion for crackless design • Ease of construction and maintenance • Cost minimization Jae Yu: GEM Based DHCAL

  5. DHCAL Gas Amplification Requirements • Sufficiently large gain for good S/N ratio • Minimize cross-talk between cells in readout • Isolated readout path from active volume to avoid coherent noise • Modularity, retaining continuity for gas and HV supplies and readout • Digitized readout from each cell • Allow pad design to avoid strip ambiguity • Keep low HV for safety and reliability • Simple readout electronics for cost savings and reliability Jae Yu: GEM Based DHCAL

  6. DHCAL Requirements for EFA • Small cell size for good multiple track separation • High efficiency for MiPs in a cell • Possibility for Multiple thresholds • Avoid aligned dead area such as support structure Jae Yu: GEM Based DHCAL

  7. GEM (Gas Electron Multiplier) Approach • GEM developed by F. Sauli (CERN) for use as pre-amplification stage for MSGC’s • GEM also can be used with printed circuit readout – allows very flexible approach to geometrical design. • GEM’s with gains above 104 have been developed and spark probabilities per incident  less than 10-10. • Fast operation -> Ar CO2 40 ns drift for 3mm gap • Relatively low HV (~ few x100V per GEM layer) • (cf. 10-16kV for RPC!) Jae Yu: GEM Based DHCAL

  8. Why GEM? • GEM developed by F. Sauli (CERN) for use as pre-amplification stage for MSGC’s • Allow flexible and geometrical design, using printed circuit readout  Can be as fine a readout as GEM tracking chamber!! • High gains, above 104,with spark probabilities per incident  less than 10-10 • Fast response • 40ns drift time for 3mm gap with ArCO2 • Relative low HV • A few 100V per each GEM gap compared to 10-16kV for RPC • Rather reasonable cost • Foils are basically copper-clad kapton • Some $400 per framed 10cmx10cm foil Jae Yu: GEM Based DHCAL

  9. Double GEM schematic S.Bachmann et al. CERN-EP/2000-151 Jae Yu: GEM Based DHCAL

  10. Large amplification 140mm 70mm CERN-open-2000-344, A. Sharma Jae Yu: GEM Based DHCAL

  11. r=70mm GEM Foils • Most foils made at CERN • A total of about 1000 foils made • COMPASS experiment has large scale, 31cmx31cm, GEM • Kapton etching most difficult step  Work with Sauli’s group A. Sharma CERN OPEN-98-030 Jae Yu: GEM Based DHCAL

  12. GEM gains High gain Low voltage differential!! From CERN GDD group Jae Yu: GEM Based DHCAL

  13. Embeded onboard readout Ground to avoid cross-talk Design for DHCAL using Triple GEM Jae Yu: GEM Based DHCAL

  14. Readout Schematic Anode pad Ground thr thr AMP DISC AMP DISC REG REG Digital/serial output Jae Yu: GEM Based DHCAL

  15. Triple GEM test chamber • Sufficient space for foil manipulation • Readout feed-through, retaining large space for ease of connection • Clear cover to allow easy monitoring • Readout pads connection at the bottom J. Li, UTA Jae Yu: GEM Based DHCAL

  16. GEM Prototype Pad Contact Design Carefully designed to avoid discharge J. Li, UTA Jae Yu: GEM Based DHCAL

  17. }1cm }1cm GEM prototype – readout path Readout through a gas tight feed-through Jae Yu: GEM Based DHCAL

  18. UTA GEM Test Chamber HV layout 2.9kV Could be achieved with +/- 1500V Jae Yu: GEM Based DHCAL

  19. UTA GEM Prototype Status • Constructed • Test chamber box • Readout circuit board (1cmx1cm pads) • HV layout design complete • Two GEM foils arrived and two more on the way Jae Yu: GEM Based DHCAL

  20. Single GEM gain/discharge probability • Simulation study in progress using multi-jet final states • Understand average total charge deposit in a cell • Study fake signal from spiraling charged particle in the gap A.Bressan et al, NIM A424, 321 (1998) Jae Yu: GEM Based DHCAL

  21. GEM aging study A. Sharma CERN OPEN-98-030 Jae Yu: GEM Based DHCAL

  22. UTA Simulation Status and Plans • Two masters students working on this project • Mokka installed as the interface to Geant4 • Pandora-Pythia HEPEvt ASCII output working (Many thanks to Masako Iwasaka from U. of Tokyo!!!)  Why ASCII output? • Generated 1000 t`t6 jet events at ECMS=500GeV and processed through Mokka for GEM discharge study • In the process of analyzing the data using vanilla root macro  Are there a reconstruction and analysis packages for Mokka (V8?) • Output format needs improvement  A file per event per detector component is not that helpful for sophisticated studies • In the process of implementing Mokka geometry database • To implement prototype GEM cell geometry • Plan to study detailed design and performances • Plan to use in EFA and tracking algorithm development Jae Yu: GEM Based DHCAL

  23. Summary • UTA development supported by both DoE ADR and local funds • Collaborate with CALICE collaboration for development • Test chamber being constructed • Obtained two GEM foils from Sauli and two more on the way, if not they already have arrived • Detailed design work in progress • HV layout, readout structure, etc • Simulation effort making slow progress • Mokka operational • Pandora-pythia output in HEPEvt ASCII working • Working on understanding discharge probability • UTA local + SLAC simulation team • Working on GEM geometry implementation • Will collaborate with ANL for simulation and EF algorithm development Jae Yu: GEM Based DHCAL

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