NIKHEF Jaarvergadering, 21-22 Dec. 2005 1/19 Physics Studies and Track Reconstruction Physics Studies and Track Reconstruction in LHCb at NIKHEF in LHCb at NIKHEF E. Rodrigues, on behalf of the NIKHEF–LHCb group E. Rodrigues, on behalf of the NIKHEF–LHCb group CP violation / B physics CP violation / B physics - general introduction LHCb experiment LHCb experiment - basics - LHCb group @ NIKHEF Physics (preparation) Physics (preparation) studies studies - NIKHEF contributions Tracking / Reconstruction Tracking / Reconstruction - group’s involvement NIKHEF Jaarvergadering 2005 NIKHEF Jaarvergadering 2005
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NIKHEF Jaarvergadering, 21-22 Dec. 2005 1/19 Physics Studies and Track Reconstruction in LHCb at NIKHEF E. Rodrigues, on behalf of the NIKHEF–LHCb group.
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NIKHEF Jaarvergadering, 21-22 Dec. 2005 1/19
Physics Studies and Track ReconstructionPhysics Studies and Track Reconstructionin LHCb at NIKHEFin LHCb at NIKHEF
E. Rodrigues, on behalf of the NIKHEF–LHCb groupE. Rodrigues, on behalf of the NIKHEF–LHCb group
The NIKHEF LHCb reconstruction / tracking / software “team” 2005:
– Staff: Th. Bauer, H. J. Bulten, M. Merk, G. Raven– Post-docs: E. Rodrigues (CERN based), J. v. Tilburg, N. Tuning– Graduate students: J. Amoraal , E. Bos, B. Hommels, B. M’charek, J. Nardulli,
G.Ybeles Smit, M. Zupan– Undergraduate students: S. Cohen
NIKHEF software activities embedded in:
– The LHCb Computing Project (E. Rodrigues responsible for “Track Fitting”)– The Physics Planning Group (G. Raven convenor of “Proper time and mixing” WG)
Tracking / Reconstruction / Physics
NIKHEF Jaarvergadering, 21-22 Dec. 2005 5/19
NIKHEF – LHCb Group (part of)
Practicing Team buildingPracticing Team buildingBarcelona 9/’05
After Jeroen’s promotie 10/’05
NIKHEF Jaarvergadering, 21-22 Dec. 2005 6/19
Master & PhD Theses in 2005
• Jan Amoraal
• Sander Klous
• Besma M’charek•
• Jeroen van Tilburg
Jeroen van Tilburg
… after the promotie in Oct. ’05 !Thesis “Track simulation and reconstruction in LHCb”Thesis “Track simulation and reconstruction in LHCb”
ThesisThesis “LHCb: vertex detector and read out chip, “LHCb: vertex detector and read out chip,computing challenge and Bcomputing challenge and Bss -> J/ -> J/ ””
2005
PhD
PhD Post-doc … off to Zűrich in ‘06
Jan June Dec
Master
PhD Post-doc @ ATLAS
Next PhD’er on the pipeline: Bart Hommels ...Next PhD’er on the pipeline: Bart Hommels ...
… … has already a job in Cambridge!has already a job in Cambridge!
• Measurement of Measurement of angle and angle and ss
- very small in SM: sin 2- very small in SM: sin 2 = 0.04 = 0.04
- any large asymmetry means new physics- any large asymmetry means new physics
• If If ssss is ~0.1, can do a 5 is ~0.1, can do a 5 discovery in one year, discovery in one year,almost independent of specific parametersalmost independent of specific parameters
• Time for 5Time for 5 discovery of new physics in B discovery of new physics in Bss mixing mixingdepends on the size of the new physics contribution…depends on the size of the new physics contribution…
BsJ/ψφ (Bs tagged)
Proper time τ (ps)
Such an observed distribution would mean new physics …Such an observed distribution would mean new physics …
Marko ZupanGoal:Goal: Study of inclusive b -> s Study of inclusive b -> s decaysdecays
Theoretical interest:Theoretical interest: Rather sensitive to new physics via loopsRather sensitive to new physics via loops
(e.g. SM vs SUSY)(e.g. SM vs SUSY)
Experimental aspects:Experimental aspects: BR ~ 10BR ~ 10-6-6 … too low for B-factories … … too low for B-factories … In practice XIn practice Xss is made “as inclusive as possible” is made “as inclusive as possible” Annual yield ~ 9000 events!Annual yield ~ 9000 events!
Magnetic field map:Magnetic field map: Participation in B-field map measurementsParticipation in B-field map measurements Responsible for including the real field map in software, for physicsResponsible for including the real field map in software, for physics
NIKHEF Jaarvergadering, 21-22 Dec. 2005 13/19
Tracking Strategy in LHCb
A typical event:A typical event: 26 long 26 long tracks tracks best quality for physics: good P & IP resolution best quality for physics: good P & IP resolution 11 upstream tracks 11 upstream tracks lower p, worse p resol., but useful in the RICH1 pattern recognition lower p, worse p resol., but useful in the RICH1 pattern recognition 4 downtream tracks 4 downtream tracks improves K improves Kss finding efficiency (good p resolution) finding efficiency (good p resolution) 5 seed/T tracks 5 seed/T tracks used in the RICH2 pattern recognition used in the RICH2 pattern recognition 26 VELO tracks 26 VELO tracks used in primary vertex reconstruction: good IP resolution used in primary vertex reconstruction: good IP resolution
|B| (T)
Z (cm)
B-field measured to ~ 0.03% precision!B-field measured to ~ 0.03% precision!
very high rate reduction ~400!very high rate reduction ~400!
- Peak resol. < 100 MeV- Peak resol. < 100 MeV
- Promissing trigger for calibration data …- Promissing trigger for calibration data …
under further study …under further study …
L1L1 tracking tracking
Online Pattern Recognition
L0L0 tracking tracking
Bart HommelsNiels Tuning
J/mass peak @ the L1 trigger
Pile-up veto strategies / algorithm (and hardware) is NIKHEF responsibilityPile-up veto strategies / algorithm (and hardware) is NIKHEF responsibility Performance & robustness studies being finalizedPerformance & robustness studies being finalized Pile-up veto detector can also be used for a luminosity measurementPile-up veto detector can also be used for a luminosity measurement
NIKHEF Jaarvergadering, 21-22 Dec. 2005 15/19
Offline Pattern Recognition
Henk Jan BultenBart HommelsJeroen van TilburgGabriel Ybeles Smit
OfflineOffline tracking in numbers: tracking in numbers: ~ 95% B-decay products found~ 95% B-decay products found Ghost rate ~ 3%Ghost rate ~ 3%
NIKHEF contributions:NIKHEF contributions:
- Responsible for seeding PR in the T stations- Responsible for seeding PR in the T stations
- getting it ready for a realistic detector- getting it ready for a realistic detector
T2T2 T3T3T1T1Efficiency for long tracksEfficiency for long tracks
ε ~ 95% (p>5 GeV)
NIKHEF Jaarvergadering, 21-22 Dec. 2005 16/19
Track Fit à la Kalman
Eduardo RodriguesJeroen van Tilburg
Benefits of the Kalman filter technique:Benefits of the Kalman filter technique: Mathematically equivalent to least Mathematically equivalent to least 22 method method Adds measurements recursivelyAdds measurements recursively
starting from a initial track estimatestarting from a initial track estimate Reconstructs tracks including multiple scattering and energy lossesReconstructs tracks including multiple scattering and energy losses
Ongoing work:Ongoing work:
- Adapting fit for a realistic detector …- Adapting fit for a realistic detector …
Edwin BosMarcel MerkGerhard RavenEduardo RodriguesJeroen van Tilburg
Warped TT sensors
“banana-shaped” Outer Tracker modules
Needs:Needs: Tracking in a realistic environment:Tracking in a realistic environment:
• move away from ideal MC to real worldmove away from ideal MC to real world• tilted and/or deformed detectorstilted and/or deformed detectors• deal with misalignmentsdeal with misalignments
Idea:Idea: Use the concept of “trajectories” developed in BaBarUse the concept of “trajectories” developed in BaBar
• a track’s trajectory can be approximated locallya track’s trajectory can be approximated locally as a parabolaas a parabola• one could also parameterize locally a detectorone could also parameterize locally a detector element with a measurement (hit) as a element with a measurement (hit) as a parabola, whatever the shape of the whole isparabola, whatever the shape of the whole is
Track fit is then “reduced” to a à la Kalman Track fit is then “reduced” to a à la Kalman minimization of distances between local parabolic minimization of distances between local parabolic trajectories approximations!trajectories approximations!
track fit blind to details of detector shapes and track fit blind to details of detector shapes and misalignementsmisalignements
NIKHEF Jaarvergadering, 21-22 Dec. 2005 18/19
In short …
Excellent group spiritExcellent group spirit
Lots of interesting, exciting and fun workLots of interesting, exciting and fun work
Heavy involvement in a variety of Heavy involvement in a variety of complementarycomplementary aspects of LHCb preparation for aspects of LHCb preparation for « physics @ day 1 »« physics @ day 1 »
Activities & responsibilities cover the A-to-Z of the Activities & responsibilities cover the A-to-Z of the building of a HEP experimentbuilding of a HEP experiment
Outer Tracker construction and testing VELO hardware contributionsOuter Tracker construction and testing VELO hardware contributions
OT software VELO software contributionsOT software VELO software contributions
OT alignment studiesOT alignment studies
pattern recognition in OT & other trackerspattern recognition in OT & other trackers
track reconstruction and fittingtrack reconstruction and fitting