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RHIC-Phenix 実験のための EMCalorimeter のテスト実験と

その性能評価

Outline•Introduction•Beam test setup•Calibration method•Position dependence•Resolution & Linearity•Conclusion

鳥井久行 , 今井憲一 , 延與秀人 , 後藤雄二 , 斎藤直人 , Terry Awes,Stefan Bathe, Damian Bucher, Henner Buesching, Mikhail Ippolitov,

Edouard Kistenev, Vanessa Mexner, Thomas Peitzmann,Ullich von Poblotzki, Sebastian White

京大 , 理研 , BNL, Kurchatov.I, U.Muenster, ORNL

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IntroductionRHIC-PHENIX Experiment

• RHIC– Heavy Ion collision

s = 200AGeV

– collision s = 200 & 500 GeV

• PHENIX– Muon arms

– Central arms• EMCal ..

Photon/Electron physics

p p

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Introduction- Requirements for PHENIX EMCal-

• Wide dynamic range• to perform both H.I physics and spin physics

– Energy range 1: a few hundred MeV - 20GeVfor both H.I. physics and spin physics in s = 200AGeV

• Thermal , 0 - a few hundred MeV - a few GeV

• J/ee - 　　　　　　　　 < 10 GeV

• Direct - a few GeV - 20 GeV

– Energy range 2: 10GeV - 80GeVfor spin physics s = 500GeV

• Direct - a few GeV - 40 GeV• We , Zee - 10 GeV - 60 GeV

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Introduction- Requirements for PHENIX EMCal -

– Requirement for cross section measurement

– 2% uncertainty corresponds to 10% cross section measurement error because of steep PT distribution

pT = 2% = 10% AGS beam test< 7GeV

CERN beam test

10GeV-80GeV　 NEW

• Energy Calibration to achieve 2% accuracy

2%

10%

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• PbSc (lead-scintillator) and PbGl (lead glass)

• Fine segmentation– good /0 separation

• To cover wide energy range– two different HV setting are appl

ied• for s = 200GeV run

• and s = 500GeV run

PbSc 1 module (4 towers)

PHENIX EM CalorimeterPbSc PbGl

Mod.(cm x cm) 55.2 x 55.2 4.0 x 4.0Depth(cm) 37.5 40ch a n ne l s15552 9216

Sampling fraction ~ 20% 100%WLS fibers 6 x 6

cov. 0.7 0.7 cov. 90+45deg 45deg/ mod 0.011 0.008 / mod 0.011 0.008

X0 18 14.4Molière Radius ~ 3cm 3.68cm

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Beam Test SetupAt the CERN SPS H6 beam line from Aug.29 to Sep.5 1998

(by sharing beam with ALICE/Phos group)Absolute Beam Momentum 0.6% at 40GeV/c

(from uncertainties of magnet current and alignment)

Beam Momentum bite 0.6-0.8% (adjustable with slits setting)Separated e / beam (/e < 1% ) 　 was achieved by target & absorber se

tting and by CEDAR(differential renkov)

DWC(Delayline Wire Chamber) - position measurement.

-counters select

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Beam Test Setup

PbSc(1SM)

PbGl(4SM’s)

(Shipped from BNL)

(from WA98)

70c

m

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Data set - PbSc -PbGl - Analyzed by Muenster group

PbSc - shown in this talk

Purpose Menu Beam condit i o nStatisticLinearity &,Resolution ,

Energyscan

(6),10,15,20,30,40,80GeV/ c e-

10k-60k/ energy

Shower profile Positionscan

20GeV/c e- 160k

Hadron rejection, Hadron,response

40GeV/c + 50k

Non- orthogonal, Anglescan,

10,15,20,30,40GeV/c e-10,20degree

10k-20k/energy/degree

Calibration 10GeV/c

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Calibration method- how to translate ADC(Amplitude) to energy-

• Muon beam and Electron beam– Correction of gains between channels– 50% -200% / channels

• Laser– Correction of gain drift– 2 - 3% / 60 mins

• Position dependence– 11 % /55.2mm

• Absolute energy– Calibrated at 20 GeV beam energy

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Calibration method

– <ADC(ch)> = (ADClow - pedestal ) <high/low Ratio>

(ADChigh - pedestal)

– <Calib Factor(GeV/ch)> = <Factor(t=0)> <Gain Drift(t-0)>

<Gain1 Drift(t-0)> = <Truncated Mean of ADC>

143..1i i

i

0) laser(t of ADC

laser(t) of ADC

0) laser(t of ADC

laser(t) of ADC

<Energy(GeV)> = <ADC(ch)> x <CALIB Factor(GeV/ch)>

<Total Energy(GeV)>

= <Energy(GeV)> x <Position Dep>55

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Calibration method- Position Dependence -

• Hit position dependence of the total observed energy

• Difference of position dependence in several 1/4 channels are within 2%

• 7%(edge) - 11%(corner) 2% It is parameterized by simple

function with hit position in 1/4 channel

Correction with parameterized function make hit position dependence to be flat.

E/E = 0.5%It’s used in real data analysis

Beam

corner

center

edge

1/4 channel

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Calibration Method- Uncertainty -

Linearity Resolution

– Pedestal <0.1% 0.2 - 1.5%

– High/Low Ratio 0.5% 0.5%

– Gain Correction(t=0) 2% (3% for ) 0.4-1.0%

– Gain Drift(t0) 0.3% <0.2%

– Position Dependence ----- 0.5%

Total 2% Uncertainty

(channel by channel)

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Result- Resolution & Linearity -

• 10 - 80GeV beam data are taken

• Almost symmetric peak shape

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Results- Resolution -

• Resolution• Fit by HEBT only• 1.0%+8.7%/E

– After subtraction of contributions

• momentum bite

• pedestal

– 1.3%+7.9%/E for AGS data which is taken at less than 7GeV

1.0%+8.7%/E

1.3%+7.9%/E

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Results- Linearity -

• Energy responses for 20GeV - 80GeV are linear within 2% uncertainty.

• There is 4% deviation at 10GeV.– Attenuation in WLS fibers and effect of shower leakage compensate.– We measure energy response function with

• Laser system , 0,J/ mass reconstruction (PMT+FEE) (EMCal+PMT+FEE)

2% uncertainty

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Results- Hadron rejection -

• Hadron rejection was studied at 40GeV/c +,e- beam• With only energy cut at the electron peak (>36GeV)

it results in

~100 factor hadron rejection• It will improve using shower profile cut.

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Conclusion

• Energy resolution 1.0%+8.7%/E for 10 - 80GeV

• Energy response for 20GeV - 80GeV is linear within 2% uncertainty

• With two different HV settings.

• At 10GeV, there is 4% deviation. We measure the response function.

• Requests for PHENIX EMCal was achieved