gem dhcal simulation studies j. yu* univ. of texas at arlington alcw, july 15, 2003 cornell...
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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
July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell
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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)
July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell
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Resolution curve – TESLA TDR
I know this is about 10% higher than others.
Estimate of 2.5% systematic uncertainties included
July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell
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Double GEM schematic
S.Bachmann et al. CERN-EP/2000-151
July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell
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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
July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell
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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
July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell
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Energy Deposit for 10 GeV Pions (GEM)
fEM>=0.85
Remaining Total
fHC>=0.85
July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell
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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
July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell
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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
July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell
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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
July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell
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GEM Digital Response
July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell
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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
July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell
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N vs Layer
Energy Deposit/Ncells vs Layers for 50 GeV Pions
E vs Layer
July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell
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Extraction of of dE/dN
July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell
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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
July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell
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GEM MIP Digital Threshold Efficiency
Energy Deposited (MeV)
Eff
icie
ncy
95% efficiency
At 0.23MeV
Energy Deposit
MIP Efficiency
July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell
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Discharge Study: NPairs for Muons in GEM
July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell
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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
July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell
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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
July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell
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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
July 15, 2003 Jae Yu: UTA GEM DHCALALCW, Cornell
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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
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