Transcript UTA simulation efforts

UTA GEM DHCAL SIM
J. Yu*
Univ. of Texas at Arlington
Nov. 7 - 9, 2002
NIU/NICADD
•Introduction
•Digital Hadron Calorimeter Requirements
•GEM in the sensitive gap
•UTA GEM DHCAL Prototype Status
•Simulation Status
•Summary
(*On behalf of the UTA team; A. Brandt, K. De, S. Habib, V. Kaushik, J. Li, M. Sosebee, A. White)
Introduction
• LC physics topics
– Distinguish W from Z in two jet final states  Good jet mass resolution
– Higher Jet energy resolution;  E ~ 30% E
– Excellent jet angular resolution
Jet
Jet
• 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  Good
position resolution
• 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
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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
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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
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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
• Relatively 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
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Large
amplification
140mm
70mm
CERN-open-2000-344, A. Sharma
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GEM gains
High gain
Low voltage
differential!!
CERN GDD group
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Double GEM
DHCAL Design
Embeded
onboard
readout
Ground to
avoid
cross-talk
Anode
pad
Ground
AMP
DISC
Thr.
AMP
REG
Nov. 7, 2002 Digital/serial
output
DISC
REG
Thr.
Preliminary readout design
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Double GEM test chamber
•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 top
2cmx2cm pad design
J. Li, UTA
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UTA GEM Test Chamber HV layout
2.1kV
Drift gap
Transfer gap
HV fed from one
supply but
individually
adjusted 
Good to prevent
HV damage on
the foils
Induction gap
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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 (LeCroy
HQV800)
Nov. 7, 2002
Amplification
factor of 300
for 5xGEM
size signal
(LeCroy
HQV800 )
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Want to know how GEM Foils look like?
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Single GEM gain/discharge probability
Simulation study in
progress using single
pions before multi-jets
•Determine Maximum
total charge deposit in
a cell of various sizes
and gains
•Study fake signal
from spiraling charged
particle in the gap
A.Bressan et al, NIM A424, 321 (1998)
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UTA Simulation Status
• Two masters students have been working on this project
– Pandora-Phythia implementation and HEPEvt ASCII output in
place
– Mokka successfully installed
– Mokka Geometry database downloaded and installed at UTA
– Completed single pion studies using default geometry
• Reproduced expected response
• Energy resolution seems to be reasonable also
– Preliminary mixture GEM geometry implemented
– Single pion study with mixture GEM begun
• Root macro and JAS based analysis packages developed
• Proceed with more detailed GEM geometry
implementation
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Single Pion Studies w/ Default TESLA Geometry
• 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 3.47% and agrees with the computed
sampling fraction
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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)
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TESLA TDR detector live
energy deposit for single pions
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TESLA TDR Elive vs E
%
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TESLA TDR CAL Single Pion
Resolution
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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
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GEM Prototype Geometry
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GEM Geometry Implementation
Mechanics in Mokka
TDR / Hcal02 Model chosen
for modification
Fe-GEM sub-detector
instead of the existing FeScintillator
New driver for the HCal02
sub-detector module
Local database connectivity
for HCal02  Database
downloaded and implemented
at UTA
Courtesy: Paulo deFrietas
Nov.Venkat,
7, 2002 TSAPS Meet Oct 10 - 12, 2002
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Single Pion Cell Energy Deposit in
GEM HCal
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Single pion Energy with GEM
50GeV 
ELive
15GeV 
EMeas
10.6MeV
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GEM Sampling Weight
Live Energy Deposit (MeV)
300
Sampling: 2~4x10-3
250
200
150
Statistics too low to produce
Series1
reliable
gaussian fit  This
depends
heavily
on EM section
Linear
(Series1)
without proper GEM gain factor
taken into account.
100
50
0
0
10
20
30
40
50
60
Incident Pion Energy (GeV)
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Summary
• Hardware prototype making significant progress
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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 3M in Austin, Texas
• Simulation effort made a marked progress
– Single pion study of Mokka default TESLA TDR geometry complete
• Analysis tools in place and seem to work well
• The resolution seems to be reasonable
– Preliminary GEM Mixture geometry implemented
• Need to redo the response study with gain factored in…
– 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 factor will come soon
– Will soon move onto realistic events, WW, ZZ, or t`t  jets
– Still ways to go before effective EFA and TRKA studies
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