digital hcal using gem j. yu* univ. of texas at arlington nov. 7 - 9, 2002 nicadd/niu (*on behalf of...

Digital HCAL using GEM J. Yu*

Univ. of Texas at ArlingtonNov. 7 - 9, 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, 2002 Jae Yu: GEM Based DHCAL 2

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

JetJet EE%30~


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


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


• 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


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


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– ~$400 for a specially prepared and framed 10cmx10cm foil


CERN-open-2000-344, A. Sharma

Large amplification

70m

140m


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=70m

Nov. 7, 2002 Jae Yu: GEM Based DHCAL 10CERN GDD group

GEM gains

Low voltage differential!!

High gain


Double GEM DHCAL Design

Ground to avoid cross-talk

Embeded onboard readout

AMP DISC

REG

Digital/serial output

Thr. Thr.

Anode pad

Ground

REG

AMP DISC

Preliminary readout design


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


UTA GEM Test Chamber HV layout

2.1kVDrift gap

Transfer gap

Induction gap

HV fed from one supply but individually adjusted Good to prevent HV damage on the foils


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 )


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


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


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


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 CalorimeterMaterial:•18 mm of Fe •6.5 mm of Polystyrene scintillator (in green)


TESLA TDR detector live energy deposit for single pions


TESLA TDR Elive vs E

%


TESLA TDR CAL Single Pion Resolution


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 104 will be on the order of 107 for single 200GeV pions

– Getting pretty close to the 108 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


GEM Prototype Geometry


GEM Geometry Implementation Mechanics in Mokka

TDR / Hcal02 Model chosen for modification

Fe-GEM sub-detector instead of the existing Fe-ScintillatorNew driver for the HCal02 sub-detector moduleLocal database connectivity for HCal02 Database downloaded and implemented at UTA

Courtesy: Paulo deFrietas

Venkat, TSAPS Meet Oct 10 - 12, 2002


Single pion study with GEM

15GeV

5GeV


Cell Energy Deposit in GEM HCal


GEM Sampling Weight

GEM Sampling Weight

y = 3.9373x + 51.969

0

50

100

150

200

250

300

0 10 20 30 40 50 60

Incident Pion Energy (GeV)

Liv

e E

ner

gy

Dep

osi

t (M

eV)

Series1

Linear (Series1)


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 107 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 tt jets

digital hcal using gem j. yu* univ. of texas at arlington nov. 7 - 9, 2002 nicadd/niu (*on behalf of...

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