Tracking for 2015

Target

Verify the performance of LHCb Tracking algorithms with the new beam conditions in 2015 (=13TeV, bunch spacing=25,50 ns) and be prepared for various data-taking scenarios.

Useful samples

There are many useful samples in bookkeeping that can be used to perform your studies:

Data Samples

• 2011, 25ns: /LHCb/Collision11_25/Beam3500GeV-VeloClosed-MagDown/Real Data/Reco11a/90000000 ( Full stream )/RAW : these events are taken without any trigger. No data is actually on disk. If needed, we can request to copy them temporarily to disk.
• 2012, 25ns: /LHCb/Collision12_25/Beam4000GeV-VeloClosed-MagDown/Real Data/90000000 ( Full stream )/RAW : useful for tracking performance studies
• 2012, 25ns: /LHCb/Collision12_25/Beam4000GeV-VeloClosed-MagDown/Real Data/Reco14/Stripping20/90000000 ( Full stream )/(various streams) : useful for comparing physics signal yields and efficiencies
• 2012, High Luminosity: /LHCb/Collision12hl/Beam4000GeV-VeloClosed-MagDown/Real Data/90000000 ( Full stream )/RAW : useful for tracking performance studies
• 2012, High Luminosity: /LHCb/Collision12hl/Beam4000GeV-VeloClosed-MagDown/Real Data/Reco13g/Stripping20/90000000 ( Full stream )/(various streams) : useful for comparing physics signal yields and efficiencies [beware: Reco13g, not Reco14]

N.B.: The RAW data samples are on tape, they can be duplicated on disk upon request. For tracking studies one can refer to the DST streams in Stripping20.

MC Samples

N.B.: There is an issue with the DST samples. The "Link/Raw/(Detector)/Clusters" containers are not filled, therefore clusters truth-matching is not possible. This samples cannot therefore be used for Tracking performance measurements using the PatChecker algorithm. XDIGI samples need to be used instead.

RunII

• 13TeV, RunII, MinBias: /MC/Dev/Beam6500GeV-RunII-MagDown-Nu1.9-25ns-Pythia8/Sim08f/30000000 ( minbias )/XDIGI : for minimum bias studies
• 13TeV, RunII, Physics: /MC/Dev/Beam6500GeV-RunII-MagDown-Nu1.9-25ns-Pythia8/Sim08f/( evtid )/XDIGI : a few physics channels for physics studies

All of this samples are generated for magnet Up and Down and for different running conditions:

• 25ns: Nu=1.6,1.9
• 50ns: Nu=1.6,2.7

RunI

• 8TeV, RunI, MinBias: /MC/2012/Beam4000GeV-2012-MagDown-Nu2.5-Pythia8/Sim08e/Trig0x409f0045 /30000000 ( minbias )/XDIGI : for minimum bias studies
• 8TeV, RunI, Physics: /MC/2012/Beam4000GeV-2012-MagDown-Nu2.5-Pythia8/Sim08e/Trig0x409f0045 /( evtid )/XDIGI : a few physics channels for physics studies

All of this samples are generated for magnet Up and Down.

Condition Databases

The suggested condition databases for running on these samples are (11/2/2014):

• CONDDB: cond-20130710
• DDDB: dddb-20130929-1
• SIMCOND: sim-20131023-vc-md100, sim-20131023-vc-mu100

Ongoing activities and responsible people

This is a list of specific topics to see who is currently working on what, broader topics and responsible people are listed below.

Topic	Description	Contact	Link
Combinatorics in T-stations	Check if hits can be (better) preselected	???	???
Fitting framework	Provide fitting framework for all chi2-fits, vectorisable	Manuel Schiller,...	???
Vectorising pat reco	Vectorise the hotspots of the pattern recognition	Gerhard Raven, ...	???
Speeding up Kalman filter	Can we speed up the Kalman filter, using vectorised libraries/code	???	???
Adaptive windows	Can we use adaptive windows in the patreco (depending on position, event multiplicity, ...)	???	???
Floats	Rewrite the patreco using float instead of doubles	???	???
Online -> Offline tracks	Can/should offline tracks be constructed from online tracks?	???	???
Update / Check params in pat reco	Update all parametrisations in the patreco algorithms to latest MC	???	???

Detailed Wish List

Topic	Algorithm	Proponent	Comment	Timescale	Started	Finished	Responsible
Pattern Recognition Fit	General	Manuel Schiller
Trade ghost rate for efficiency	Velo	David Hutchcroft	almost at limit
Lite cluster decoding	Velo	Kurt Rinnert
double vs. float	Velo	Kurt Rinnert
2nd metal layer effect	Velo
Clustering thresholds	Velo
Improve clustering	Upstream	Barbara Storaci
Velo+VeloTT+Forward efficiency loss recovered by matching?	Upstream	Barbara Storaci
Code review	Upstream	Barbara Storaci
Optimised search regions	Upstream	Barbara Storaci
TT addition after Velo+VeloTT+Forward still needed?	Upstream	Barbara Storaci
Require confirming stereo hit when adding x hit?	Forward	Michel De Cian
"Precluster" layer	Forward	Michel De Cian
Better way to sort subranges	Forward	Michel De Cian
Region and occupancy dependent search windows	Forward	Michel De Cian
TT hit adding smarter and faster	Forward	Michel De Cian	waiting until TrackMatching in 'obsolete' to simplify interface	Middle of November	yes	yes	Michel
Pooled allocation for hits	Forward	Michel De Cian
floats vs. double	Forward	Michel De Cian
AOS vs SOA hits	Forward	Michel De Cian
High threshold bit for silicon detectors	Forward	Michel De Cian
Ambiguity resolution via pitch residuals? Simfit in x,y?	Forward	Michel De Cian
Hit cleaning in busiest region of OT	Seeding	Manuel Schiller
Kill unused OT hits early in the reco	Seeding	Manuel Schiller
Kill hits from previous/next bunch crossing	Seeding	Manuel Schiller
Use wire propagation time?	Seeding	Manuel Schiller
Port upgrade studies?	Matching	Michel De Cian	Tuning and some improvements done. Small improvements still possible, if errors correctly propagated from Velo and Seed	End of December	yes	yes	Michel
Backport upgrade version?	Downstream	Michel De Cian	basic version backported, gain smaller than expected, investigate...	End of year (?)	yes		Michel
Improvement of equation of motion of charged particle in magnetic field	Kalman Fit	Wouter Hulsbergen, Gerhard Raven
Calculate more quickly energy loss and multiple scattering corrections	Kalman Fit	Wouter Hulsbergen, Gerhard Raven
Node/measurement creation, improve the allocation	Kalman Fit	Wouter Hulsbergen, Gerhard Raven
TrackProjectors: TrajPoca really needed for straight line hits?	Kalman Fit	Wouter Hulsbergen, Gerhard Raven
Matrix operations	Kalman Fit	Wouter Hulsbergen, Gerhard Raven
OT hits in high occupancy regions	Kalman Fit	Wouter Hulsbergen, Gerhard Raven
OT decoding improvements possible?	Kalman Fit	Wouter Hulsbergen, Gerhard Raven
Check tracks for hit overlap very fast?	Kalman Fit	Wouter Hulsbergen, Gerhard Raven
Advanced algorithms monitoring (efficiency, timing, ghosts)	Monitoring	Michel De Cian, Manuel Schiller			yes		Svende
High-level Quantities Monitoring	Monitoring
Tune ghost probability	ghost probability	Michel De Cian		end of 2014			Paul
Overlap online-offline	online-offline	Vava Gligorov		end of January 2015			Sascha
Implement improved multiple-scattering correction	Kalman Fit	Miriam Hess					Miriam

Tracking Algorithms Performance

Task Force: Manuel Schiller, Michel De Cian, Sebastian Neubert.

PrChecker tables

The following tables show the output of the PrChecker for 1000 events of B->K*mumu for different running scenarios:

• 25ns, Nu 1.5: PrCheckerReco15DevKstmumuMagDown25nsNu15.txt
• 25ns, Nu 1.9: PrCheckerReco15DevKstmumuMagDown25nsNu19.txt
• 25ns, Nu 2.6: PrCheckerReco15DevKstmumuMagDown25nsNu26.txt
• 50ns, Nu 2.7: PrCheckerReco15DevKstmumuMagDown50nsNu27.txt
• 50ns, Nu 3.4: PrCheckerReco15DevKstmumuMagDown50nsNu34.txt
• 50ns, Nu 4.8: PrCheckerReco15DevKstmumuMagDown50nsNu48.txt
• MC 2012 for comparison: PrCheckerMC2012KstmumuMagDown.txt

Additionally it was checked how the behaviour would be for the highest running scenarios when cutting on the SPD multiplicity:

• 25ns, Nu 2.6, SPD < 450: PrCheckerReco15DevKstmumuMagDown25nsNu26SPD450.txt
• 25ns, Nu 2.6, SPD < 600: PrCheckerReco15DevKstmumuMagDown25nsNu26SPD600.txt
• 25ns, Nu 2.6, SPD < 900: PrCheckerReco15DevKstmumuMagDown25nsNu26SPD900.txt
• 50ns, Nu 4.8, SPD < 450: PrCheckerReco15DevKstmumuMagDown50nsNu48SPD450.txt
• 50ns, Nu 4.8, SPD < 600: PrCheckerReco15DevKstmumuMagDown50nsNu48SPD600.txt
• 50ns, Nu 4.8, SPD < 900: PrCheckerReco15DevKstmumuMagDown50nsNu48SPD900.txt

The upstream numbers in all tables are wrong due to a wrong setting.

The following PrChecker tables (5k events) are with Reco15 for 2015 data taking and obtained from Sim08f samples:

• 25ns, Nu 1.6: PrCheckerReco15KstmumuMagDown25nsNu16Sim08f.txt
• 25ns, Nu 1.9: PrCheckerReco15KstmumuMagDown25nsNu19Sim08f.txt

For reference the same with the Sim08e samples:

• 25ns, Nu 1.5 Sim08e: PrCheckerReco15KstmumuMagDown25nsNu16Sim08e.txt
• 25ns, Nu 2.3 Sim08e: PrCheckerReco15KstmumuMagDown25nsNu23Sim08e.txt
• 25ns, Nu 2.6 Sim08e: PrCheckerReco15KstmumuMagDown25nsNu26Sim08e.txt

Velo Tracking

Velo Pattern Recognition contacts: David Hutchcroft and Kurt Rinnert

Standalone T reconstruction

T seeding contact: Manuel Schiller

Long Track Reconstruction

There's a presentation by Paul https://indico.cern.ch/conferenceDisplay.py?confId=280286 It can be reproduced with the instruction in Phys/TrackingScripts/TrackEffMCStudies/README. The Brunel options produce two TTrees, one comparing the TrackBestTrackCreator to the TrackEventCloneKiller, one for comparing PatForward with PatMatch.

Forward Tracking

Forward contacts: Michel De Cian

Track Matching

Downstream Tracking

Downstream contacts: Adam Davis, Mike Sokoloff and Mika Vesterinen

Upstream Tracking

VeloTT contacts: Barbara Storaci and Marco Tresch

Clone Killer

Open question: Why are forward tracks preferred over match tracks after the Kalman filter? Better chi2? More hits on track?

Possible Improvements

There are a few studies performed on the tracking for the upgrade that may be ported to the current tracking:

• VeloTTFor2015
• DownstreamFor2015

Running the tracking on top of HLT found tracks:

• StagedReconstruction

Tracking Efficiency

contact: Michael Kolpin

Detectors Performance

Velo

TT

IT

contact: Mark Tobin

OT

contact: Francesco Dettori and Niels Tuning

Further checks are ongoing on the drift time.

Outer Tracker performance with 25ns has been studied using the data recorded in 2012. These studies are outlined in the Performance of the LHCb Outer Tracker.

Muon

Validation

A tool is needed for validating the reconstruction software. Differences among two reconstruction software versions should be analysed by means of tracking specific quantities and physical quantities. Contact: Svende Braun

(Open) Issues

• The definition of "from B" and "from C" changed in summer (see Rev 159594). The PatChecker / TrackChecker have been updated on 23.1.2014 to only flag daughter particles from mesons and baryons as "from B" or "from C" (which is the correct definition). Without this update there might be slightly lower efficiencies for these categories.
• There may be differences between the simulated and actual detector response with 25ns. Investigation with detector and simulation experts is ongoing.
• The "Link/Raw/(Detector)/Clusters" containers are not filled, therefore clusters truth-matching is not possible on the DST Monte Carlo since Sim08.

Obsolete code

The following classes have not been used since a long time in the tracking and are not forseen to be used in the future. They might become subject to removal (after an announcement and contacting the authors).

• AddTTClusterTool - Alternative to PatAddTTCoord, which share an interface.
• TrackMatchVeloSeed - Old version of the Matching
• TrackMatch, and all the old TrackMatch algorithms (?)
• TrackSeed* - Old version of seeding (?)

All of this code has been put in obsolete (November 15 2014).

Presentations with 2015 tracking contributions

• Maurizio's kick-off presentation Kick-off for 2015 improvements
• Ideas by Manuel Schiller: Possible improvements of Pattern Recognition
• Daniel's (explicit) vectorsation for the upgrade: Explicit vectorisation for PrPixel
• Manuel's brainstorm summary and first developments Output of the brainstorming for Reco15
• Svende's presentation of the new PrChecker SuperTrackEffChecker
• Espen's improvement for VeloTT: VeloTT improvements
• Tracking & Alignment meeting, November 20: T&A, Nov 20
• Tracking & Alignment meeting, November 27, 2014: T&A, Nov 27, 2014
• Tracking & Alignment meeting, January 8, 2015: T&A, Jan 8, 2015
• Tracking & Alignment meeting, January 13, 2015: T&A, Jan 13, 2015
• Tracking & Alignment meeting, January 27, 2015: T&A, Jan 27, 2015
• Tracking & Alignment meeting, February 5, 2015: T&A, Feb 5, 2015
• Tracking & Alignment meeting, February 10, 2015: T&A, Feb 10, 2015
• Tracking & Alignment meeting, February 19, 2015: T&A, Feb 19, 2015

-- MichelDeCian - 30 Jan 2015