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KEK Beam Test KEK Beam Test AnalysisAnalysis

Hideyuki Sakamoto15th MICE Collaboration Meeting

10st June,2006

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ContentsContents

• Setup of KEK beam test• Alignment correction• Light yield• Tracking within B-Field• Summary

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KEK Beam TestKEK Beam Test• KEK beam test was performed on S

eptember 30th to October 7th in 2006 at KEK-PS 2 beam line with the collaboration of UK, US, Europe and Japan. Main purpose is to confirm the performance of SciFi tracker in 1-Tesla solenoid field.

• Prototype SciFi tracker– SciFi tracker is consists of 4 sta

tions, and there are 3 views for station B,D and 2 views for station A,C.

• VLPCs– Photon signals from Scintillating

fiber were readout by VLPCs.– We used two VLPC cassettes. O

ne of them has high gain and the other has low gain.

– VLPCs were cooled down to 9K by a cryocooler.

Schematic view of detectors Schematic view of detectors located in the beam linelocated in the beam line

Prototype SciFi Tracker Prototype SciFi Tracker with 4 Stationswith 4 Stations

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SetupSetup

TOF hodoscopeTOF hodoscope

JACEE MAGNET (B=1T)JACEE MAGNET (B=1T)

Readout SystemReadout System

CryocoolerCryocooler

AFE BoardAFE Board

Low GainLow Gain CassetteCassette

High GainHigh Gain CassetteCassette

Before installing waveguidesBefore installing waveguides

BEAMBEAM

2 Beam Line2 Beam Line

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Analysis Analysis SchemeScheme

• This analysis aims to estimate light yield and efficiency. First, fiber hits are defined on each view. Then, tracks are reconstructed in the 3 stations other than the test station, and are extrapolated to the test station. Finally, the residual between extrapolated track and the hits on the test station is calculated. Residual distribution is also calculated by Monte Carlo to be compared with data.

• Hit definition– A fiber channel of which measured pulse height is above

2.5 photo-electron is defined as a hit. Most of VLPC noise are rejected by this cut.

• Tracking– Track is reconstructed by 2D tracking using 3 stations

other than the test station. Hits on the test station are not included in the tracking. To select good tracks, chi-squared of the reconstructed track is required to be less than 1.

• 2D tracking is performed at each Views individually.

BEAM

3 GeV/c 3 GeV/c

D C A B

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Event SelectionEvent Selection

• To ensure that a pion surely passes through SciFi tracker, PID by TOF of D1 and D2 counter are required.

• Integration window in Trip chip is measured. Time difference from the beam trigger is restricted to reject events in which beam particles are not synchronized to Trip gate.

STATION B STATION A

STATION DSTATION C

D1TOF D2SciFi

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Alignment CorrectionAlignment Correction

• This study is based on latest mapping table, Version12.

• Alignment correction as well as mapping error is checked by finding difference of hit fibers with fibers which is extrapolated by fitting.

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Alignment CorrectionAlignment Correction

View V

View X

View W

Station B

Fiber # Residual

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Alignment CorrectionAlignment Correction

View V

View X

Station A

Fiber # Residual

Res

idua

l

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Alignment CorrectionAlignment Correction

View X

View W

Station C

Fiber # Residual

Res

idua

l

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Alignment CorrectionAlignment Correction

View V

View X

View W

Station D

Fiber # Residual

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Searching for center Searching for center fiberfiber

• In order to find combination of crossing of fibers of 3 views, adjustment is done by shifting X-view by same amount.– Down figure shows the results after shifting by -

20 fibers.

W view

X view

V view

#101 #101

#81

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Pitches for Station DPitches for Station D

• In design, all 3 Views in new 4th Station D has 427 m pitches. But DATA shows it is 420 m as other Views.

Diff

eren

ce o

f fib

er#

Fiber#

V ViewV View

X ViewX View

W ViewW View

Red = 427 m

Black = 420 m

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Light Yield –X viewLight Yield –X view

7.9 ±0.1 p.e. 10.3± 0.2 p.e.

8.8±0.2 p.e. 4.7±0.1 p.e.

14.5± 0.4 p.e. 18.6 ±0.9 p.e.

8.5 ±0.6 p.e.

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Light Yield –V viewLight Yield –V view

8.6±0.1 p.e. 9.1±0.1 p.e.

4.7±0.2 p.e.

15.6±0.4 p.e. 15.3±0.4 　 p.e.

9.1±0.5 p.e.

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Light Yield –W viewLight Yield –W view

9.8 ±0.2 p.e.

9.0±0.1 p.e. 5.1±0.2 p.e.

16.8 ±0.4 p.e.

9.4±0.5 p.e.

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Light Yield SummaryLight Yield Summary

Station ViewGain of cassette

3HF concent.

Light Yield@PION

Light Yield@PROTON

Ratio

B X LOW 5000 7.9 15.0 1.9

B V LOW 2500 8.6 15.6 1.8

B W LOW 3500 9.8 16.9 1.7

A X LOW 5000 10.3 18.6 1.8

A V LOW 5000 9.1 15.3 1.7

C X HIGH mixture 8.8 --- ---

C W HIGH 5000 8.9 --- ---

D X HIGH 2500 4.7 8.5 1.8

D V HIGH 2500 4.8 9.1 1.9

D W HIGH 5000 5.1 9.4 1.8

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Analysis SchemeAnalysis Scheme• Tracking reconstruction is held by MC in order to

compare with DATA.– 250 MeV/c muon beam is used for this analysis.– Initial beam of 4cm x 4cm squared distribution with Pt

=0 are used for MC simulation and beam profile at TOF hodoscope is compared.

• Reconstructed Pt,Pz distribution and chi2 distribution are compared with MC.

BEAM250MeV/c 250MeV/c

D C A B

1 Tesla

TOFT1

4cm

x4c

4cm

x4c

mm

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Beam Profile –MC and Beam Profile –MC and DATADATA

DATA MC

Horizontal Width (cm)

10.0 10.0

Vertical Width (cm) 10.0 10.0

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Pt, Pz Distribution – MCPt, Pz Distribution – MC

Station @X view

D C A B

Pt (MeV/c) 28.5 (8.6) 29.0 (9.7) 29.4 (10.3) 29.4 (10.0)

Pz (Mev/c) 227.2 (2.3)

226.8 (2.4) 226.4 (2.4) 225.9 (2.4)

Station Station BB

PT distributionPT distribution

MeV/c MeV/c

MeV/c MeV/c

MeV/c MeV/c

MeV/c MeV/c

Station Station CC

Station Station AA

Station Station DD

PZ distributionPZ distributionStation Station BB

Station Station CC

Station Station AA

Station Station DD

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Pt ,Pz Distribution – DATAPt ,Pz Distribution – DATAMuon

electron

muon

pion

PT distribution

PZ distribution

PT distribution

PZ distribution

MeV/c

MeV/c

MeV/c

MeV/c

Reconstructed mom.

Muon

Pt (MeV/c) 28.3 (10.3)

Pz (Mev/c) 230.7 (26.7)

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Reconstructed Distri. – MCReconstructed Distri. – MC

Reconstructed mom.

Muon

Pt (MeV/c) 30.1 (10.3)

Pz (Mev/c) 233.7 (19.7)

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Chi2 Distribution –MC and Chi2 Distribution –MC and DATADATA

• Chi2 is defined by residue of hit position and reconstructed track divided by sigma, 1mm.

• Peaks around 1 is the same as MC. But width is little more broad than MC. It should be checked.

Mean RMS

DATA 2.8 2.3

MC 1.8 1.6

DATADATA MCMC

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SummarySummary• Alignment corrections are done using latest mapping tabl

e, Version12.• Light yield for all views of all stations are studied by 3D tr

acking.– There is no big difference with 3 kinds of 3HF concentration (exce

pt for StationD).

• Tracking with B-Field are studied.– Reconstructed Pt, Pz distribution looks like same with MC and DA

TA.– Chi2 distribution of MC also looks like same as DATA, which conf

irms that DATA is reconstructed as expected.– Next step is estimating momentum resolution by MC.

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BackupBackup

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Light YieldLight Yield• Light yield is estimated

by fitting the peak with gaussian.

• Measured light yield is similar to the result of cosmic-ray test.

Station B A C D

3HF Concentration (ppm)5000 5000

mixture

2500

Gain of cassette Low Low High High

Measured light yield (p.e.) 8.1 10.3 8.7 5.1

Data from Cosmic-ray test 8.5 9.1 8.7 n/a

This peak is caused This peak is caused by ADC saturation.by ADC saturation.

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Residual DistributionResidual Distribution

Station B A C D

Sigma (mm) @ DATA

1.285 +/- 0.009

0.491 +/-0.003

0.505 +/-0.004

0.635 +/-0.004

Sigma (mm) @ MC

1.24 +/-0.01

0.457 +/-0.004

0.434 +/-0.007

0.535 +/-0.005

DATADATA MCMC

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EfficiencyEfficiency

• Efficiency is determined by N1/ N2;– N1= Number of events which contains fiber hits within

the road width determined at each station – N2=Number of events with L1A cut & TOF(D1&D2) , and

required fiber hits above 2.5 photo-electron in every views.

Station B A C D

Road width (mm) 4 2 2 2

Efficiency (%) @ DATA

98.0 98.8 99.5 96.6

Efficiency (%) @ MC 99.92 99.99 100 99.97

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SummarySummary• KEK beam test was performed in the fall of 2006.• Stability of VLPC are checked.

– Pedestal peak is within 1 count,– Pedestal width is within 1-2%,– Gain is stable within 2%, and– Noise rate is within 5-8%.

• Light yield and efficiency are studied with 3GeV/c pion beam without B-Field.Station B A C D

3HF Concentration (ppm)5000 5000

mixture

2500

Gain of cassette Low Low High High

Measured light yield (p.e.) 8.1 10.3 8.7 5.1

Light yield from Cosmic-ray test

8.5 9.1 8.7 n/a

Measured efficiency (%) 98.0 98.8 99.5 96.6

Expected efficiency (%) 99.92 99.99 100 99.97