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TRD-prototype testat KEK-FTBL

11/29/07~12/6

Univ. of TsukubaHiroki Yokoyama

The TRD prototype is borrowed from GSI group (thanks Anton).

KEK-FTBL

• KEK, Fuji Test Beam Line• 2007/11/29-12/6• 3GeV/c,electron beam

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Beam Area

TRD-prototype

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4

setup

Scintillation CounterTRD MRPC PbGlass

Trig for TOF

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.

6Pulse height is defined as sum of three adjacent pad’s induced charges.

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Gas GainAr+CO2(85,15) Xe+CO2(85,15) Drift Voltage

-2100VAnode Voltage

1500V1450V1400V1350V1300V

Gas gain by avalanche can be fitted by exponential

function of anode voltagePul

se h

eigh

t at

Am

p re

gion

Me

an

pu

lse

he

igh

t

time time

Anode voltage

Anode voltage vs pulse height

Ar+CO2(85,15)Xe+CO2(85,15)

Mea

n pu

lse

heig

ht

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Drift velocity Anode Voltage

1500VDrift Voltage

-2100V-2000V-1900V-1800V-1700V

Drift velocity for Ar gas is about three times larger than that for Xe gasD

rift

Ve

loci

ty

Electric Field of Drift region

Electric field vs Drift velocity

Ar+CO2(85,15)Xe+CO2(85,15)

time time

Ar+CO2(85,15) Xe+CO2(85,15)

Me

an

pu

lse

he

igh

t

Me

an

pu

lse

he

igh

t

Electron attachment

9The attenuation of signal by H2O or oxygen depends on time that

electrons stay in the chamber.

Attenuation of signal by electron attachment

a/b is defined as sign of electron attachment.

a

b

Stay time of electron

a/b

Ar+CO2(85,15)Xe+CO2(85,15)

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Anode Voltage1500V

Drift Voltage-2100V

With RadiatorWithout Radiator

before after

before after

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TR-photon signal(1)•Correct time distribution to be flat shape in the drift region

time

time time

time

Ar+CO2(85,15)

Xe+CO2(85,15)

TR-photon attachment

Depth of detector from drift electrode(mm)

Ar+CO2(85,15)Xe+CO2(85,15)

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TR-photon signal(2)

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Depth of TRD-prototype is 30mm.95%(in Xe),28%(in Ar) TR-photon energy is absorbed.

•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.

absorption length

€

λ =89mm(in Ar)

10mm(in Xe)

⎧ ⎨ ⎩

⎫ ⎬ ⎭

resolution in azumuthal direction

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Data for fit

Calculate center

1pad(=8mm)

Resolution(angle 0°)is about 400μm12

Pad number

Measure difference between this point and fited line

Angle=20°

angle resolution

0° 391±10μm

10° 605±28μm

20° 1071±22μm

30° 1614±45μm

time time

Pad

nu

mbe

r

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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