TPC PAD Optimization

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TPC PAD Optimization

• Yukihiro Kato (Kinki Univ.)

1. Motivation
2. Simple Monte Carlo simulation
3. PAD response
4. PAD response for two tracks
5. Summary Plan

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Motivation
? We are planning to use TPC with MPGD(Micro
pattern Gas Detector) as a main tracker. ?
Advantage of MPGD -- small EB
effect -- detect real electron with
small spread -- large gain (103-104) ?
Candidates of readout for TPC are GEM and
Micromegas.
?To achieve the fine spatial resolution and the
two track separation on the TPC. ? Need fine
pixel read out pad to achieve above items?
Study of PAD optimization!!
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What determine the PAD shape?
? of channel (12M channel _at_ 1mm 1mm PAD) ?
Read out method (analog or digital etc.)
PAD shape size
? sRf 150µm (drift distance 0235cm) ? 2
hit separation 2mm
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Optimization of PAD by Simple Monte Carlo
simulation
Estimate PAD shape size by Monte Carlo
Simulation. --- Using the detailed
simulation(Geant4) is better way to
optimized PAD shape. --- We start the PAD
optimization using simple Monte Carlo
simulation.
Simple simulation can optimize PAD size as first
step. ? The electron generated along a track
drift to MPGD. ? The electrons amplified
by MPGD reach the PAD. ? We estimate the
number of electrons in PAD with various PAD
sizes.
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Simple Monte Carlo simulation

1. Primary electron cluster is generated along a
   track.
2. Making the primarysecondary electron clusters.
3. Drift the electrons to GEM with dispersed by
   Diffusion .
4. Distributed the electrons at closest GEM hole.
5. GEM holes amplify the electrons.
6. Move the electrons to PAD with dispersed by
   Defocusing.
7. Counting the of electron on each PAD.

Todays results takes into account the effect (3)
and (6). (First step of the very simple
simulation) --- Gas diffusion constant CD
80µm/vcm (TDR gas, 3T) --- Defocusing s
100µm --- GEM gain 103
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PAD response
? Shape of PAD is a rectangle (1cm0.15, 0.5,
1.0, 2.0 mm) ? Generate Single primarysecondary
electron at a fix point. ( electron of
the cluster is 100) ? Making the distribution of
electron in the PAD and estimate the s.
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PAD response
(PAD width 150 µm)
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PAD response
(PAD width 500 µm)
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PAD response
(PAD width 1mm)
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PAD response
(PAD width 2mm )
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PAD response for two tracks
? Shape of PAD is a square. ? The distance of two
track is 2mm. Both track pass
through 45 for X , Y-axis. ? Generate
electrons along a track ( electron is
100/cm) ? Making the distribution of electron
in the PAD and estimate the s.
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PAD response for two tracks
(Drift distance is 235cm)
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PAD response for two tracks
(Drift distance is 235cm)
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PAD response for two tracks
(Drift distance is 235cm)
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PAD response for two tracks
(Drift distance is 20cm)
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PAD response for two tracks
(Drift distance is 20cm)
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Summary Plan
? Just started the PAD shape size optimization
by simple Monte Carlo simulation. ? The
size of electron dispersing due to the diffusion
of the drift gas. TDR gas is not good for
MPGD/TPC. ? Complete the simple simulation and
find the good PAD shape size. ? Further
study using the detailed simulation.