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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