Development of Digital Hadron Calorimeter Using GEM

Development of Digital Hadron Calorimeter Using GEM

Shahnoor HabibFor HEP Group, UT Arlington

Oct. 12, 2002TSAPS Fall ’02, UT Brownsville

Simulation of GEM using available software

Oct. 12, 2002 DHCAL with GEMTSAPS Fall ‘02, S. Habib, UTA

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Introduction• Linear Collider

– A future HEP accelerator which studies forces in nature – Use electron-positron collisions for the study– High center of mass energies: 500GeV-3TeV

• Examples of Linear Collider – TESLA – (Tera Electon Volt Energy SuperConducting Linear Collider)

Germany– NLC – Next Generation Linear Collider in the US – JCL – Japan Linear Collider

• For the HEP research at the LC– Need a good jet energy resolution of the calorimeter

• Use a Technique called Energy Flow Algorithm• Need high granularity More readout channels• Need to control costs Digital hadron calorimeter a solution

• Couple of designs for DHCAL depending on sensitive gap– Scintillation counter, GEM, RPC (Resistive Plate Chamber)


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•The gas electron multiplier (GEM) consists of a thin, metal-clad polymer foil, chemically pierced by a high density of holes.

•How does it work?

•GEM as a detector or as an pre-amplifier

•Large overall gains (104 with spark probabilities per incident pion less than 10-10) in harsh radiation environment.

•Fast response (50ns drift time for 10mm gap with ArCO2)

•Relatively low voltage (A few 100V compared to 10-16KV for Resistive Plate Chamber)

•Reasonable cost (Foils are basically copper-clad kapton - $4 for a specially prepared framed 1cm2)

Why GEM?


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Ionization electrons released by ionization fall thru the holes and get amplified in the electric field represented by red & green lines and then drift to collection regions.

Large amplification


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Discharge Characteristics of GEM

• Important characteristic for reasonable calorimeter• To see the discharge characteristics of GEM without

using GEM because GEM is still under design and construction stage I had to simulate GEM using computer software that is available for High Energy Physics.

• Default geometry and then later GEM geometry• Study single particle events


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Software used in the simulation• Detector simulation involve

– Event generation– Detector simulation of the event– Reconstruction– Analysis

• Software used for event generation is Pandora_Pythia version 3.2.

• Software used for Detector simulation is Mokka and the default detector is TDR- TESLA Design Report.

• Program ROOT for analysis


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Mokka Detector Simulation

• Mokka is full detector simulation for the TESLA detector calorimeter.

• Mokka has been used extensively for the TESLA T.D.R calorimeter energy flow studies.

• Advantage of Mokka is that it is object oriented program and hence provides a facility to add sub detector of our design to replace Mokka’s default sub-detector and that is going to be our next stage. This is the stage on which my colleague Venkat is going to give a talk.


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TESLA TDR 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)


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Single Pion Studies • 1000 single pion events using Mokka particle gun

command. – Mokka produced 1000 hits file for ecal – 1000 hits files for hcal– kinematics information on primary particles in the files

• Energies of Incident particle – 5 - 200 GeV

• 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


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Conclusion• Digital Hadron Calorimeter augmented with Energy

Flow is a possible solution for obtaining good jet energy resolution

• UTA is developing a DHCAL with GEM as the sensitive gap

• Sanity check of the analysis package completed• After the successful installation and testing of

Pandora_Pythia, Mokka and Root, the next steps are to– incorporate GEM geometry in the Mokka TDR detector and

study the discharge characteristics of GEM.– Run LCDRoot for reconstruction of events– Study characteristics of GEM-DHCAL

Development of Digital Hadron Calorimeter Using GEM

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