GEM DHCAL Simulation Studies J. Yu* Univ. of Texas at Arlington ALCW, July 15, 2003 Cornell University (*on behalf of the UTA team; S. Habib, V. Kaushik,

GEM DHCAL Simulation Studies J. Yu*

Univ. of Texas at ArlingtonALCW, July 15, 2003Cornell University

(*on behalf of the UTA team; S. Habib, V. Kaushik, J. Li, M. Sosebee, A. White)

•Introduction•Analog Studies: TDR vs GEM•Preliminary GEM Digital Studies•Initial EFA studies with GEM•Summary

July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell

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Introduction• DHCAL a solution for keeping the cost manageable for EFA• Finer cell sizes are needed for effective calorimeter cluster

association with tracks and subsequent energy subtraction • UTA Has been working on DHCAL using GEM for

– Flexible geometrical design, using printed circuit readout– Cell sizes can be as fine a readout as GEM tracking chamber!!– High gains, above 103~4,with spark probabilities per incident less

than 10-10

– Fast response• 40ns drift time for 3mm gap with ArCO2

– Relatively low HV• A few 100V per each GEM gap

– Reasonable cost• Foils are basically copper-clad kapton• ~$400 for a specially prepared and framed 10cmx10cm foil


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UTA GEM Simulation • Use Mokka as the primary tool

– Kept the same detector dimensions as TESLA TDR– Replaced the HCAL scintillation counters with GEM

(18mm SS + 6.5mm GEM, 1cmx1cm cells) • Single Pions used for initial studies

– 3 – 100 GeV single pions– Analyzed them using ROOT

• Compared the results to TDR analog as the benchmark– GEM Analog and Digital (w/ and w/o threshold)


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Resolution curve – TESLA TDR

I know this is about 10% higher than others.

Estimate of 2.5% systematic uncertainties included


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Double GEM schematic

S.Bachmann et al. CERN-EP/2000-151


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UTA Double GEM Geometry

3.4 mm ArCO2

GEM3.1 mm

Simple GEM

Detailed

GEM0.

00

51

.

0

Cu

Kapton

ArCO2

G10

0.

00

5

6.5mm


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Comparison of Detailed and Simple GEM Geometries

Detailed GEM75GeV

• 25.2sec/event for Simple GEM v/s 43.7 sec/event for Detailed GEM• Responses look similar for detailed and simple GEM geometry• Simple GEM sufficient

<E>=0.80 0.007MeV <E>=0.81 0.008MeV

Simple GEM75GeV


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Energy Deposit for 10 GeV Pions (GEM)

fEM>=0.85

Remaining Total

fHC>=0.85


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EM-HAD Relative Weighting Factor • To compensate the response differences

between ECAL and GEM HCAL responses a procedure to normalize them had to be introduced– ELive=EEM+ W gEHAD (g:GEM Intrinsic gain)

– Obtained the relative weight W using two Gaussian fits to EM only v/s HAD only events

– Perform linear fit to Mean values as a function of incident pion energy

– Extract ratio of the slopes Weight factor W– E = C* ELive


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GEM

GEM Response (Analog)

Estimate of 2.5% systematic uncertainties included

Sampling fractions are as expected for both TDR and GEM TESLA TDR


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GEM

GEM Resolution (analog)

Systematic uncertainties for GEM amplified by 50% to reflect unconsidered sources

We just cannot make the resolution as good as our French colleagues saw.

TESLA TDR


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GEM Digital Response


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GEM Cell Occupancies

~85% single hit

~15% >1 hit

~74% single hit

~26% >1 hit

Number of cells with higher number of hits increase w/ E


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N vs Layer

Energy Deposit/Ncells vs Layers for 50 GeV Pions

E vs Layer


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Extraction of of dE/dN


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GEM Digital Response

Estimate of 2.5% systematic uncertainties added to analog. Digital analysis w/ syst. in progress.GEM Digital

Sampling fractions are consistent between digital and analog.

GEM Analog


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GEM MIP Digital Threshold Efficiency

Energy Deposited (MeV)

Eff

icie

ncy

95% efficiency

At 0.23MeV

Energy Deposit

MIP Efficiency


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Discharge Study: NPairs for Muons in GEM


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Single GEM gain/discharge probability

A.Bressan et al, NIM A424, 321 (1998)

Single pion study almost completed•Understand average total charge deposit in a cell of various sizes•Study fake signal from spiraling charged particle in the gap


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Single Pion EFA Study

Track-cluster association is the first step for a good EFA•Must work for simplest cases•Start with single pion in analog and digital cases•Fit the centroid of shower using energy weighted (analog) and numerically averaged (digital) center in each layer•Measure the distance between fit shower position and the particle incident position

E=50 GeV


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E weighted vs Numerical Mean)

E = 50 GeV1cm x 1 cm cells

E weighted

<>=-3.1x10-5

=1.1x10-2

Numerical Mean

<>=-1.2x10-3

=2.5x10-2

Analog seems to be better than digital but not by significant factor


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Summary• UTA’s GEM based DHCAL simulation has made

significant progress in the past year• First pass single particle studies completed with a M.S.

thesis, using Mokka:– GEM analog resolution comparable to TDR – GEM digital seems to be comparable to GEM analog– GEM digital with threshold will complete soon– Fit method refinement in progress

• EFA studies began– Single particle study seems to show reasonable performance

in E weighted vs numerical means– Jet final state studies will come next

• Funding for ½ student for this effort available

Documents

GEM DHCAL Simulation Studies J. Yu* Univ. of Texas at Arlington ALCW, July 15, 2003 Cornell University (*on behalf of the UTA team; S. Habib, V. Kaushik,