Transcript 20080300_TRDmeeting_report

TRD-prototype test
at KEK-FTBL
11/29/07~12/6
The TRD prototype is borrowed from GSI group (thanks Anton).
Univ. of Tsukuba
Hiroki Yokoyama
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KEK-FTBL
• KEK, Fuji Test Beam Line
• 2007/11/29-12/6
• 3GeV/c,electron beam
Beam Area
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TRD-prototype
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setup
Scintillation Counter
TRD
MRPC
Trig
for TOF
PbGlass
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measurement
• Pad Response Function
• Amplification of signals (through anode voltage and
gas dependence)
• Electron attachment (through drift voltage
dependence)
• Drift velocity (through drift voltage and gas
dependence)
• Absorption of TR-photon（absorption length in
2type gases, Ar+CO2(85,15),Xe+CO2(85,15))
• Angle dependence of position resolution
Pad Response Function
• distance from CM vs. proportion of induced charge to sum of them.
• Full width of signal sharing in azimuthal direction is 3pads.
Pulse height is defined as sum of three adjacent pad’s induced charges.
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Mean pulse height
Ar+CO2(85,15)
time
Xe+CO2(85,15)
Drift Voltage
-2100V
Anode Voltage
1500V
1450V
1400V
1350V
1300V
time
Anode voltage vs pulse height
Ar+CO2(85,15)
Xe+CO2(85,15)
Pulse height at Amp region
Mean pulse height
Gas Gain
Gas gain by avalanche can
be fitted by exponential
function of anode voltage
Anode voltage
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Drift velocity
Xe+CO2(85,15)
Mean pulse height
Mean pulse height
Ar+CO2(85,15)
time
Anode Voltage
1500V
Drift Voltage
-2100V
-2000V
-1900V
-1800V
-1700V
time
Electric field vs Drift velocity
Drift Velocity
Ar+CO2(85,15)
Xe+CO2(85,15)
Drift velocity for Ar gas is about
three times larger than that for Xe
gas
Electric Field of Drift region
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Electron attachment
a/b is defined as sign of
electron attachment.
Attenuation of signal by
electron attachment
b
a
a/b
Ar+CO2(85,15)
Xe+CO2(85,15)
Stay time of electron
The attenuation of signal by H2O or oxygen depends on time that
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electrons stay in the chamber.
TR-photon signal(1)
•Correct time distribution to be flat shape in the drift region
Xe+CO2(85,15)
before
after
Anode Voltage
1500V
Drift Voltage
-2100V
With Radiator
Without Radiator
time
time
Ar+CO2(85,15)
after
before
10
time
time
TR-photon signal(2)
•Calculate the TR photon contribution as the difference between time
distributions with/without radiator.
•By slope of exponential fit, I calculated absorption length of TR-photon in each
gas.
TR-photon attachment
absorption length
89mm(in Ar)
  

10mm(in Xe) 

Ar+CO2(85,15)
Xe+CO2(85,15)
Depth of detector from drift electrode(mm)
Depth of TRD-prototype is 30mm.
95%(in Xe),28%(in Ar) TR-photon
energy is absorbed.
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Calculate
center
time
Pad number
resolution in azumuthal direction
time
Data for fit
Angle=20°
angle
1pad(=8mm)
resolution
0°
391±10μm
10°
605±28μm
20°
1071±22μm
30°
1614±45μm
Measure difference between
this point and fited line
Resolution(angle 0°)is about 400μm
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summary
• Signal share is less than 3 pads.
• Gas gain by avalanche can be fitted by
exponential function of anode voltage.
• Drift velocity in Ar gas is about three times
larger than that in Xe gas.
• The attenuation of signal by hydrogen and
oxygen depends on time that electrons stay
in the chamber.
• absorption length in Xe(Ar) is 10mm(89mm)
• Resolution(angle 0°) is 391μm.
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