1. Digital HCAL using GEM J. Yu* Univ. of Texas at Arlington, 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) Introduction Digital Hadron Calorimeter Requirements GEM in the sensitive gap UTA GEM DHCAL Prototype Status Simulation Status Plans for Hardware, Simulation & Algorithms Summary

2. Aug. 28, 2002Jae Yu: GEM Based DHCAL2 Introduction LC physics topics –Distinguish W from Z in two jet final states  Good jet mass resolution –Higher Jet energy resolution; –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 –Best known method for jet energy resolution improvement Large number of readout channel will drive up the cost for analogue style energy measurement  Digital HCAL Tracking calorimeter with high gain sensitive gap

3. Aug. 28, 2002Jae Yu: GEM Based DHCAL3 DHCAL General Requirements Thin and sensitive readout layer for compact design 1 or 2 level digital 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 effective

4. Aug. 28, 2002Jae Yu: GEM Based DHCAL4 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

5. Aug. 28, 2002Jae Yu: GEM Based DHCAL5 Small cell size for good multiple track shower separation High efficiency for MiPs in a cell for effective shower particle counting Possibility for Multiple thresholds Dense and compact design for quick shower development to minimize confusion Large tracking radius with optimized magnetic field for sufficient separation between tracks for shower isolation DHCAL Requirements for EFA

6. Aug. 28, 2002Jae Yu: GEM Based DHCAL6 Goals for UTA DHCAL Development Develop digital hadron calorimetry for use with EFA –Aim for cost effective high granularity –Look for a good tracking device for the sensitive gap Develop GEM cell(s) and prototype Develop module/stack design for EFA optimization Simulate GEM behavior in calorimeter Implement GEM readout structure into simulation Develop EF and calorimeter tracking algorithms Cost effective, large scale GEM DHCAL

7. Aug. 28, 2002Jae Yu: GEM Based DHCAL7 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 10 4,with spark probabilities per incident  less than 10 -10 Fast response –40ns drift time for 3mm gap with ArCO 2 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 –~$400 for a specially prepared and framed 10cmx10cm foil

8. Aug. 28, 2002Jae Yu: GEM Based DHCAL8 Double GEM schematic S.Bachmann et al. CERN-EP/2000-151

9. Aug. 28, 2002Jae Yu: GEM Based DHCAL9 CERN-open-2000-344, A. Sharma Large amplification 70  m 140  m

10. Aug. 28, 2002Jae Yu: GEM Based DHCAL10 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 r=70  m

11. Aug. 28, 2002Jae Yu: GEM Based DHCAL11 CERN GDD group GEM gains Low voltage differential!! High gain

12. Aug. 28, 2002Jae Yu: GEM Based DHCAL12 Triple GEM DHCAL Design Ground to avoid cross-talk Embeded onboard readout AMP DISC REG Digital/serial output Thr. Anode pad Ground REG AMP DISC Preliminary readout design

13. Aug. 28, 2002Jae Yu: GEM Based DHCAL13 Triple GEM test chamber J. Li, UTA 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 1cmx1cm pad design

14. Aug. 28, 2002Jae Yu: GEM Based DHCAL14 GEM prototype – readout path }1cm Readout through a gas tight feed-through on the test chamber Double copper clad with 1cmx1cm pads readout through the holes on the other side Board being redesigned due to complication in the readout hole contact

15. Aug. 28, 2002Jae Yu: GEM Based DHCAL15 UTA GEM Test Chamber HV layout 2.9kV Could be achieved with +/- 1500V HV fed from one supply but individually adjusted Drift gap Transfer gap Induction gap

16. Aug. 28, 2002Jae Yu: GEM Based DHCAL16 UTA GEM Prototype Status Constructed –Test chamber box –Readout circuit board (1cmx1cm pads)  being redesigned –HV layout design complete –Two GEM foils arrived and two more on the way

17. Aug. 28, 2002Jae Yu: GEM Based DHCAL17 Single GEM gain/discharge probability A.Bressan et al, NIM A424, 321 (1998) Simulation study in progress using multi- jet final states Understand average total charge deposit in a cell of various sizes Study fake signal from spiraling charged particle in the gap

18. Aug. 28, 2002Jae Yu: GEM Based DHCAL18 UTA Simulation Status Two masters students have been 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 E CMS =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? –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

19. Aug. 28, 2002Jae Yu: GEM Based DHCAL19 Plans Year 1:Test and prototype development –Hardware Develop a test chamber for operation Produce a single layer (Absorber + TGEM) Investigate and learn production of large size GEM –Simulation and algorithm development Establish MC environment with Geant4 (Mokka?) Implement prototype GEM design (single cell) Study design for performance optimization Study and develop EFA and tracking algorithms using MC Year 2: Cosmic ray run –Hardware Build a multi-layer (>5 layers) prototype Perform cosmic ray data taking and analyses –Simulation and algorithms Simulate the single muon tracking with multi-layer geometry Develop EFA and tracking algorithms using cosmic way data

20. Aug. 28, 2002Jae Yu: GEM Based DHCAL20 Plans cnt’d Year3+4: Testbeam –Hardware Construct thicker prototype for beam exposure if the studies turn out feasible Would like to explore this possibility –Simulation and EFA/TRKA development Implement testbeam geometry for realistic simulation of TB Develop Testbeam data reconstruction Study performances with various options of EM calorimeters and tracking detectors –Need a system that can allow various plug-in detector modules without complicated geometry manipulation –Need reconstruction and analysis packages that can work in a modular manner

21. Aug. 28, 2002Jae Yu: GEM Based DHCAL21 Summary GEM based DHCAL looks feasible and interesting  UTA’s effort supported by both DoE ADR and local funds Start collaborating 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, gas supply, etc Simulation effort making slow and painful 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 for design optimization Will collaborate with ANL/NIU/SLAC for simulation and EF algorithm development