LHCb The LHCb Data Management System Philippe Charpentier CERN On behalf of the LHCb Collaboration.
Commissioning the LHCb calorimeters with cosmic rays
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Transcript of Commissioning the LHCb calorimeters with cosmic rays
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Commissioning the LHCb calorimeters
with cosmic rays
Xavier Vilasis-CardonaOn behalf of the
LHCb calorimeter group
12MAR2009 1Xvc - TIPP09
1st international conference on Technology and Instrumentation in Particle Physics TIPP09-Tsukuba, Japan, March 2009
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Y~7mX~8.5m
Z~2.7m
HCAL
ECAL
PS/SPD
LHCb Calorimeters
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10-250 mrad
10-300 mrad
VELOVertexing
MAGNET
Calorimeters
PID: e,, 0
Muon Stations
RICH 1 & 2PID: K vs.
π
Trackers TT+IT+OTMomentum resolution
• Preshower (PS)/Scintillator Pad Detector (SPD)
• Electromagnetic Calorimeter (ECAL)
• Hadronic Calorimeter (HCAL)See Andreas Schopper Talk
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Commissioning Tools
• Noise measurements• Inject known patterns into system
memories• LED system
– ECAL, HCAL, PS, SPD• Cs source for HCAL • Time Alignement events -TAE events
– Store trigger + previous and next Bunch Crossing ID (Clock cycle identifier - BXID)
– Up to 15 samples – usually 5,
• Prev2, Prev1, T0, Next1, Next2
• COSMIC RAYS• Injection Test Events
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Full System Test (May 2007)
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Concrete WALL
ECS
LED systemCalibration Pulse
ECAL Crate
Storage
Control Room
DAQTFC
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Cosmics at LHCb
• Vertical flow in cavern: – 0.9 Hz/m2 (under HCAL), <E>=50 GeV.
• PMT high voltages set initially to obtain an uniform gain on PMT of 2·105
• Trigger strategies
• First cosmics seen in December 2007• Overall more than 3M cosmic triggers
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L0Decision
Unit
ECAL
HCAL
SPD mult.
Muon
AND OR
5-15 Hz
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HCAL ECAL
PS SPD
Cosmic event in the 4 calorimeter detectorsExample of Cosmic Event in the Calorimeter
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Another cosmic event
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HCAL
ECAL
PS
SPD
HCAL ECA
LPSSPD
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Cosmic Ray crossing the SPD
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• Check channel map identification along the DAQ and trigger path.
• Relative Time Alignment– Bunch Crossing ID (Clock cycle identifier)– Integration time
• Track reconstruction in the Calorimeter– PreShower and SPD Efficiency
• Provide Trigger for other subdetectors
Cosmics use
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Correct channel mapping with comics
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Missing signal due to mapping error in
software(may 2008)
Corrected
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Trigger path validation with cosmics
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Wrong Trigger Cabling should
deliver this
Actually we had this
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Detector time alignement (muon vs calo)
• Calo-triggered event
22/04/2008 Pascal Perret - LPC Clermont
Time slot Time slot
• Muon-triggered event: Muon signal seen 2 clock cycles earlier
12MAR2009 12Xvc - TIPP09 Time slotTime slot
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Time Alignment Strategy
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• Equalise an a-priori delay from theoretical values• Adjust BXID so that an event is mainly seen on Current• Adjust integration time t0
– Select the pair of BX with maximum signal• Prev1/Current vs. Current/Next1
– Compute the asymetry R
Nevt
iij
Nevt
iij
Nevt
iij
Nevt
iij
NextECurrentE
NextECurrentERj
)()(
)()(
tT0 Next1Prev1
25 ns
δTsamplingδTsamplingδTsampling
06.20149.0 dTR
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ECAL / HCAL time alignment
HCAL
ECAL
Within each detector the RMS of R is coherent with time aligned cells within 3 ns
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PS time alignment
• Integration time is the same for 1 PMT(64 channels)
PS aligned within 4ns
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Outer Middle
Inner
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SPD time alignment
• SPD has binary output• Integration time is the same for groups of 64 channels• Asymetry is computed over the shape of the average ratio of
detected particles
Full SPD aligned within 5 ns
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Calorimeter Track Reconstruction
• A tool has been developped to reconstruct tracks in the calorimeter
• Determine azimuthal angle (φ) in HCAL & ECAL and combine them
• Select events with χ²<15• Selected tracks are extrapolated
for position & timing – PS/SPD – Other subdetectors
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PS & SPD Efficiencies
• PS – Efficiency 87 %
• SPD efficiency as a function of threshold– Threshold at 9σ above noise: ~500k
94%– Threshold at 0.5 MIP : ~1M 82 %– Threshold at 1.5 MIP : ~500k 19.6%
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PS calibration with cosmics
From Cosmics events : - Each PS region calibrated – using the time model of
signals
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Injection tests events
• SPD multiplicity was used as trigger for LHC synchronization tests• 1 injection test shot 3 h Cosmics• Coherent with cosmics results
Pascal Perret - LPC Clermont3/09/2008
Flow 0.1-1 MIP/cm2
SPD PS
Connectics problems
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Conclusions
• Calorimeter system has provided cosmic triggers to the LHCb detector
• Cosmics have allowed a first approximation to– Time alignment– Efficiency
• This procedures will be repeated with the first data
• And we are now of course
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Commissioning the LHCb calorimeters
with cosmic rays
Xavier Vilasis-CardonaOn behalf of the
LHCb calorimeter group
12MAR2009 22Xvc - TIPP09
1st international conference on Technology and Instrumentation in Particle Physics TIPP09-Tsukuba, Japan, March 2009
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Backup Slides
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Photon – electron triggger path
• ECAL -> PS/SPD->TVB tested on cosmics
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Data Quality Survey
• Check of connections with cosmics– With 900 events, if all cables were not plugged or if backplane
connections were wrong, we would see (ie we checked that all cables are plugged at the correct place):
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# hits Prs #hits SPD #hits ECAL
#hits HCAL
ECAL HCAL
Bx
Bx x x
y y
# hits Prs #hits SPD #hits ECAL
#hits HCAL
ECAL HCAL
Bx
Bx x x
y y
Time alignement PS/SPD & ECAL/HCAL
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HCAL & ECAL: Time Alignment
Pascal Perret - LPC Clermont3/09/2008
Improvement in the internal time alignment of the ECAL with the HV corrections
Aout29776
RMS(RMS R)=0.076
RMS(RMS R)=0.039Aout: 87k Event
New Run 29 776PP
Forward tracks – PP:Slope = 2.38OffSet = -2.20 ns
ΔL
TH
CA
L -
TEC
AL
ECAL
HCAL
)()(
)()(
NextNCurrentN
NextNCurrentNR
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Front End Electronics
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Calorimeter Trigger System
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LHCb DAQ System
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Cosmics in the calorimeter
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Cosmics at LHCb
• Vertical flow in cavern: – 0.9 Hz/m2 (under HCAL), <E>=50 GeV.
• Horizontal muons: – <E>=100 GeV– <30º; 0.0046 Hz/m2 (outer HCAL x 40 m2 = 0.18 Hz)– <11º; 0.0009 Hz/m2 (inner HCAL x 15 m2 = 0.013 Hz )
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Time Alignment Strategy - SPD
• SPD has binary output• Integration time is the same for groups of 64 channels• Asymetry has to be computed performing statistics over
many events• Threshold value is capital
– Too low : noise– Too high : no signal
– Fixed at 9σ from the pedestal
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t0 (ns) t0 (ns) t0 (ns)
25
25
ii
ii
NN
NN
25
25
ii
ii
NN
NN
100 GeV PGun muons (SPD inner cell), 1k events, B off Threshold ~ 0.5 MIP Threshold ~ 0.25 MIP
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SPD threshold dependence
• Using Cosmics sample study the efficiency as a function of threshold.– 9 sigma recipe: ~500k - 94%– 0.5 MIP recipe: ~1M - 82 %– 1.5 MIP recipe: ~500k - 19.6%
Correspondance of 9 sigma recipe to computed MIP
• Correction needed for cosmics• Select cosmics in middle BX
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