Nicolas du Fresne von Hohenesche Institut für Kernphysik ... · Institut für Kernphysik, Mainz...
Transcript of Nicolas du Fresne von Hohenesche Institut für Kernphysik ... · Institut für Kernphysik, Mainz...
Luminosity 2009 progress
Nicolas du Fresne von HohenescheInstitut für Kernphysik, Mainz
CERN
27. Februar 2012
COMPASS
Overview
Definition of luminosityTarget densityFlux determinationScaler MethodTrue Random Trigger MethodeComparsion
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Data
2009 DVCS data takingMuon beamLH2 targetW38 µ+ data 3900 spillsW40 µ+ data 8700 spillsW39 µ− data
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Luminosity
L = flux through target [s−1]× numbers of nucleon in target [cm−2]
Numbers for target densityDensity LH2: 0.07079 g
cm3 @ 1130mbar and 15KLength: 40 cmA: 1.01 g
mol
→ Target density : 1.6916 · 1024cm−2
Now spill by spill flux determination
→ Total integrated luminosity!
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Scaler of SF02X
96 channels read out by 6PMTDynode output of SF02X6 scaler channelsGated with DAQ busyRate written to database
timeinspill2 4 6 8 10
scal
er0
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610×scaler:timeinspill {spillnb==1}
Summation of the six scaler parts
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Geometric correction
FI02 is larger than the target → correction neededUsing beam tracks (TR Trigger) for defining fraction
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position X in cm-4 -3 -2 -1 0 1 2 3 4
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Tracks with hit in FI02 htemp3Entries 182018
Tracks with hit in FI02
position X in cm-4 -3 -2 -1 0 1 2 3 4
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htemp4Entries 142919
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htemp4Entries 142919
Tracks with hits in FI02 and target
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Geometric correction example
0 20 40 60 80 100 120 140 160 1800
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geometric scaling FI/Targetgeometric scaling FI/Target
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Corrected scaler flux
0 20 40 60 80 100 120 140 160 1800
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220610×
Corrected ScalerCorrected Scaler
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Random Trigger at COMPASS
Radioactive β+sourceAway from experimentDecay of 22Na measuredCoincidence rate ≈ 3kHz
22Na →22 Ne + e+ + νe
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True Random Trigger Method
Flux =# of random tracks
# of random trigger× time gate
Event Selection:
True Random Trigger Bit set (Trigger10) 100%Momentum!=160.00 92.8%Target cut 7.6%Hits in SiFi01 and SiFi02 6.5%Meantime cut ±5 ns (see previous talks) 6.3%
100%92.8%7.6%6.5%6.3%
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Statistical reduction
Random Trigger Bit set
Momentum!=160.0 GeV
upstream target cut
downstream target cut
Hits in FI0X
Meantime +-5ns cut
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610×Statistical reduction
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Trigger 10 and beamtracks
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histogramm1histogramm1 flux_histoEntries 1189364Mean 102RMS 57.47
Spill number0 20 40 60 80 100 120 140 160 180
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mtr
acks
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flux_histoEntries 1189364Mean 102RMS 57.47
Run 79652
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Random Trigger Flux
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610×flux_histoflux_histo
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Ratio of both methodes
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ratio_scaler_randomratio_scaler_random
0.9 0.92 0.94 0.96 0.98 1 1.02 1.04 1.06 1.08 1.10
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projectionprojection
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Results and Issues
No Random Trigger Rate for half of the runs in W38Slight different number of spills
Average random trigger rate->29403Results: W38
7.972·1011 random trigger (added RT rates)7.588·1011 scaler
Results: W40
1.712·1012 random trigger1.781·1012 scaler
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Comparsion 79652 (W38) and 79834 (W40)
Geometric factor for scaler
0 20 40 60 80 100 120 140 160 1800
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geometric scaling FI/Targetgeometric scaling FI/Target
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geometric scaling FI/Targetgeometric scaling FI/Target
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Comparsion 79652 (W38) and 79834 (W40)
Corrected scaler rate
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Corrected ScalerCorrected Scaler
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610×Corrected ScalerCorrected Scaler
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Comparsion 79652 (W38) and 79834 (W40)
Random trigger flux
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610×flux_histoflux_histo
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610×flux_histoflux_histo
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Comparsion 79652 (W38) and 79834 (W40)
Projection ratio
0.9 0.92 0.94 0.96 0.98 1 1.02 1.04 1.06 1.08 1.10
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projectionprojection
0.9 0.92 0.94 0.96 0.98 1 1.02 1.04 1.06 1.08 1.10
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projectionprojection
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