Digital HCAL using GEM J. Yu* Univ. of Texas at Arlington Nov , 2002 NICADD/NIU (*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

Nov. 7, 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

Nov. 7, 2002Jae Yu: GEM Based DHCAL3 DHCAL General Requirements Thin and sensitive readout layer for compact design One or two 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

Nov. 7, 2002Jae Yu: GEM Based DHCAL4 DHCAL Gas Amplification Requirements Sufficiently large gain for good S/N ratio (3 orders of magnitude smaller signal in gas compared to scintillation counter) 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

Nov. 7, 2002Jae Yu: GEM Based DHCAL5 Small cell size for higher position resolution for good multiple track shower separation High efficiency for MiPs in a cell for effective shower particle counting and MiP tracking Possibility for Multiple thresholds Dense and compact design for quick shower development to minimize confusion and resolution degradation Large tracking radius with optimized magnetic field for sufficient separation between tracks for shower isolation DHCAL Requirements for EFA

Nov. 7, 2002Jae Yu: GEM Based DHCAL6 Goals for UTA DHCAL Development Develop digital hadron calorimetry for use with EFA –Aim for cost effectiveness and 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

Nov. 7, 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 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

Nov. 7, 2002Jae Yu: GEM Based DHCAL8 CERN-open , A. Sharma Large amplification 70  m 140  m

Nov. 7, 2002Jae Yu: GEM Based DHCAL9 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 r=70  m

Nov. 7, 2002Jae Yu: GEM Based DHCAL10 CERN GDD group GEM gains Low voltage differential!! High gain

Nov. 7, 2002Jae Yu: GEM Based DHCAL11 Double 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

Nov. 7, 2002Jae Yu: GEM Based DHCAL12 Double 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 2cmx2cm pad design

Nov. 7, 2002Jae Yu: GEM Based DHCAL13 UTA GEM Test Chamber HV layout 2.1kV Drift gap Transfer gap Induction gap HV fed from one supply but individually adjusted  Good to prevent HV damage on the foils

Nov. 7, 2002Jae Yu: GEM Based DHCAL14 UTA GEM Prototype Status Readout circuit board (2cmx2cm pads) constructed HV Connection implemented Two GEM foils in the UTA Nano fabrication facility cleanroom Preamp in hand and characterization completed Amplification factor of 300 for GEM size signal (LeCroy HQV800 )

Nov. 7, 2002Jae Yu: GEM Based DHCAL15 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

Nov. 7, 2002Jae Yu: GEM Based DHCAL16 UTA Simulation Status Two masters students have been working on this project –Mokka Geometry database downloaded and installed at UTA –Preliminary mixture GEM geometry implemented –Completed single pion studies using default geometry Reproduced expected response Energy resolution seems to be reasonable also Root macro based and JAS based analysis packages developed Proceed with more detailed GEM geometry implementation

Nov. 7, 2002Jae Yu: GEM Based DHCAL17 Single Pion Studies w/ Default TESLA Geometry 1000 single pion events using Mokka particle gun command. –Incident energy range: 5 – 200GeV –kinematics information on primary particles in the files Developed an analysis program to read total energies deposited per pion for each incident energy. –Mean Energy vs Incident pion energies –Energy conversion from the slope of the straight line –Conversion factor is 3.54% and agrees with the computed sampling fraction

Nov. 7, 2002Jae Yu: GEM Based DHCAL18 TESLA TDR Geometry Ecal – Electromagnetic Calorimeter Material: W/G10/Si/G10 plates (in yellow) 1mm W absorber plates 0.5 mm thick Si, embeded 2 G10 plates of 0.8 mm each Hcal – Hadronic Calorimeter Material: 18 mm of Fe 6.5 mm of Polystyrene scintillator (in green)

Nov. 7, 2002Jae Yu: GEM Based DHCAL19 TESLA TDR detector live energy deposit for single pions

Nov. 7, 2002Jae Yu: GEM Based DHCAL20 TESLA TDR E live vs E  %

Nov. 7, 2002Jae Yu: GEM Based DHCAL21 TESLA TDR CAL Single Pion Resolution

Nov. 7, 2002Jae Yu: GEM Based DHCAL22 GEM Simulation Status Mokka Geometry database downloaded and installed at UTA New Geometry driver written  Mixture GEM geometry implemented  Need to use ArCO2 only Single pion study begun for discharge probability –Initial study shows that the number of electron, ion pair with gain of 10 4 will be on the order of 10 7 for single 200GeV pions –Getting pretty close to the 10 8 from other studies  Might get worse for jets from W pairs, due to fluctuation –Need more studies to compute the discharge probability. Cell energy deposit being investigated to determine optimal threshold based on cell energy  Proceed to energy resolution studies Determine optimal gain using live energy deposit vs incident energy

Nov. 7, 2002Jae Yu: GEM Based DHCAL23 GEM Prototype Geometry

Nov. 7, 2002Jae Yu: GEM Based DHCAL24 GEM Geometry Implementation Mechanics in Mokka TDR / Hcal02 Model chosen for modification Fe-GEM sub-detector instead of the existing Fe-Scintillator New driver for the HCal02 sub-detector module Local database connectivity for HCal02  Database downloaded and implemented at UTA Courtesy: Paulo deFrietas Venkat, TSAPS Meet Oct , 2002

Nov. 7, 2002Jae Yu: GEM Based DHCAL25 Single pion study with GEM 15GeV 5GeV

Nov. 7, 2002Jae Yu: GEM Based DHCAL26 Cell Energy Deposit in GEM HCal

Nov. 7, 2002Jae Yu: GEM Based DHCAL27 GEM Sampling Weight

Nov. 7, 2002Jae Yu: GEM Based DHCAL28 Summary Hardware prototype making significant progress –GEM foils delivered and are in the clean room for safe keeping –Preamp and Discriminator in hands  Preamp characterized –HV System implemented –Readout Pad implemented –Almost ready to put GEM foils in the prototype box –GEM foil mass production being looked into by 3MSimulation effort made a marked progress Simulation effort made a marked progress –Single pion study of Mokka default TESLA TDR geometry complete Analysis tools in place The resolution seems to be reasonable –Preliminary GEM Mixture geometry implemented First results seems to be a bit confusing –Initial estimate of e+Ion pair seems to be at about 10 7 for 200GeV pions –Local Geometry database implemented –Optimal threshold for digitization and gain will come soon –Will soon move onto realistic events, WW, ZZ, or t  t  jets