Introductionof my work
AYAKO HIEI (AYA)Hiroshima Univ2008/5/30
me
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Motivation : ALICE & PHOS
PHOton Spectrometer:is a electromagnetic calorimeter:consist of 5 module.
1 module consist of 56×64 PWO crystal…
…
2008/5/30 AYA / Introduction of my thesis work
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We have to calibrate each crystal
!(56×64×5=17920)
Measurement feasible region:5-80MeVenergy resolution @1GeV :3%
We can operate PHOS By remote control without being influenced by a magnetic field.
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How to calibrate energy
• In General use the incident particle of known behavior to a crystal
2008/5/30 AYA / Introduction of my thesis work
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For ExampleTest Beam (Energy)LED (signal level or fluctuation)Inclination of energy distributionMIP ,Minimum Ionization Particle(Energy) ※e.g. cosmic rayParticle by collision (e.g. Invariant mass) etc…
π0 invariant mass peak
→ γ + γ (98%)※Short life time
π0
θ
)cos1(2 21 γγγγ EEM
Mγγ
Eγ1
Eγ2
134MeV
coun
t
Reconstructed invariant mass[MeV]
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Energy calibration using pi0 mass peak
2008/5/30 AYA / Introduction of my thesis work
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π0
θ
Mγγ
Eγ1
Eγ2
BADGOOD
π0
θ
Mγγ
Eγ1
Eγ2
GOOD
GOOD
134MeV
134MeV
coun
t
Invariant mass[MeV]
110MeV
One of the two is fixed.
Dead channel??
mis calibration??
For exsampe
12In order to make this method establish
• It is necessary to:– Investigate whether the peak positions are in agreement
or not, and then the statistical error. (using simulation) – Investigate how correct can we calibrate using only γ
event on simulation, and using only pi0 event. and using collision event. etc
2008/5/30 AYA / Introduction of my thesis work
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NOW I try
12Simulated collision
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pp
ONLY PHOS
pp collision√S=14TeVEvent generator : PYTHIAEvent Bias : Minimum BiasNumber of Event : 4MNoise with a Gaussian with the RMS=4MeVAssumed a perfect calibration for each crystal
noise→I have to apply some “cut”.
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Reconstructed pi0 mass histogram : NO CUT
2008/5/30 AYA / Introduction of my thesis work
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What is this structure?
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The structure consists of noise mainly.
2008/5/30 AYA / Introduction of my thesis work
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(1)
(2)
(3)
(4)
(5)
(6)
Noisewith a Gaussian with RMS = 4MeV
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Reconstructed pi0 mass histogram : apply CUT
2008/5/30 AYA / Introduction of my thesis work
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I applypT>1GeV/cα<0.8
1876 ±941 pi0Statistics are insufficient.for investigating the mass depending on one crystal
and SO …
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The crystals are grouped in 8×7
2008/5/30 AYA / Introduction of my thesis work
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0.1261 ± 0.00230.1261 ± 0.0023 [GeV/c[GeV/c22]]
0.1282 ± 0.0015 [GeV/c0.1282 ± 0.0015 [GeV/c22]]The peak position are in agreementwith each other within the statistical errorOf 1~2%,with the perfect calibration
BUT!
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NOW I investigate the following group
2008/5/30 AYA / Introduction of my thesis work
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module 3
0 63x
y
※ALICECoordinate system
0
54
crystal numbercr
ysta
l num
ber
0.1261 ± 0.00230.1261 ± 0.0023 [GeV/c[GeV/c22]] 0.12820.1282 ± 0.0015 [GeV/c ± 0.0015 [GeV/c22]]Maybe a difference comes out most.because of Influence of a shower leakor clustering
I want to see!(I have just try it now)
12There are many things done still more
• It is necessary to:– Investigate whether the peak positions are in agreement
or not, and then the statistical error. (using simulation) – Investigate how correct can we calibrate using only γ
event on simulation, and using only pi0 event. and using collision event. etc
2008/5/30 AYA / Introduction of my thesis work
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NOW I try
Köszönöm for LISTENING2008/5/30 AYA / Introduction of my thesis work
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BACK UP : Trigger for cosmic ray
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ALICE COsmic-Ray Detector (ACORD)
12BACK UP : component
E
E’
DAQ
Data acquisition
System
PrimaryDetectingelement
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AYA / Introduction of my thesis work
12BACK UP : signal flow
Signal
Sampling count Number of sample : 70Sampling frequency :10MHz
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AYA / Introduction of my thesis work
2 Shaper!!!
12BACK UP
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BACK UP : shower shape
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AYA / Introduction of my thesis work
1 GeV electron
By Chuman thesis
electroncosmic ray
hadronic showerpunch through μ