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

2008/5/30 AYA / Introduction of my thesis work

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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

2008/5/30 AYA / Introduction of my thesis work

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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