Simulation of the 4 Layer Pixel Upgrade System (Fermilab) (For the Tracker Upgrade Simulations...

Simulation of the 4 Layer Pixel Simulation of the 4 Layer Pixel Upgrade System Upgrade System

Harry Cheung ((Fermilab)Fermilab)

(For the Tracker Upgrade Simulations Group) (For the Tracker Upgrade Simulations Group)

Outline

Technical/Software StatusPast Work on Phase 1 Simulation Studies

Current Phase 1 Simulation StudiesFuture Plan and Task List

See the talks in the Wednesday 14:00-16:00 Tracker Upgrade Simulations session;and Tuesday 14:00-18:00 Track Trigger session

for the latest results of simulation studies

Pixel Upgrade Phase 1 Meeting, 27 April 2010 H. W. K. Cheung (FNAL) 2

Technical/Software: GeometryTechnical/Software: Geometry

Full and Fast Simulations GeometryWe have a Phase 1 geometry setup for Full and Fast Simulations

• BPIX ~ from Roland’s drawings (implemented by X.Huang, H.Cheung) FPIX ~ from Simon’s drawings (implemented by P.Jindal)

– Includes option for smaller radius inner barrel layer (and beam pipe)

– Configurable sized pixels in each layer

Phase 1

Std Geom



Rechits from simulations of dimuons:

Smaller radius inner layer option

Can change pixel size via a single XML geometry file for each layer and disk



Material budget: Still some issuesBPIX cooling reweigh only, using std. geom. ladder and module construction

FPIX (services) material not completely implemented

Green Histo: Phase 1Dots: Std geometry

CMSSW_3_3_6

Material budget plots from Paul Sheldon


Technical/SW: Fast SimulationTechnical/SW: Fast Simulation

Fast Simulation with digis for faster geometry variation studiesFast Simulation “interaction geometry” also done and tuned to Full Sim

However additional issues with the Fast simulation

FullSim

FastSim

Illustration of Fast Simulation

“interaction geometry”. Standard

geometry is shown.



Material budget: Matched to Full SimulationCode to directly compare material budget between Fast and Full simulations

Green Histo: FastsimDots: Fullsim

CMSSW_3_3_6

Phase 1

Std Geom

Material budget plots from Paul Sheldon



Fast Simulation additional issue: Tracker occupanciesNo out-of-time pileup for Fast Simulation“In-time” Tracker occupancies differ in Fast and Full Sim: still investigating

• Illustration: Rates from first “Stack Layer” in Long barrel geometry:

Digi ratesSimhit rates

Occupancy plots from Emmanuele Salvati(rates for min-bias and 50 PU x 4 /module)


Technical/SW: Hits & TrackingTechnical/SW: Hits & Tracking

Tracking efficiency for dimuons with non-iterative (CMSSW_1_8_4-like) tracking and triplet seeds:

Compare smaller radius inner layer option



Tracking efficiency for dimuons with non-iterative tracking:Still issues for Fast simulation matching Full Sim in new FPIX

Phase 1

Std Geom



Still some technical work/issues with hits & tracking softwareRechit (cluster) position and errors

• Pixel hit positions and errors from code optimized for standard geometry

• Need to create appropriate code for upgrade geometry– Account for variation of pixel sizes– Account for new FPIX construction

Out-of-memory problems at high pileup (CMSSW_3_3_6)• Full simulation crashes at about 2 1034 cm-2s -1 (cannot fix)

• Tracking in Fast simulation crashes at about 4 1034 cm-2s -1 due to limit on number of clusters in code (can fix)

Tuning of iterative tracking steps• Steps 0-4 changed to use triplet seeds instead of pair seeds

– Quartet seeds not yet implemented in code

• Steps 5-6 containing strip pair seeds has to be removed for high PU

• Need to tune the selection/seeding for all steps


Technical/Software SummaryTechnical/Software Summary

Full SimulationReady to use for Phase 1 simulation studies:

• Includes smaller radius inner layer option, and configurable pixel sizes

Some improvements and geometry variation needed:• Improve BPIX material description; Put in FPIX services• Need geometry (variation) with 4th layer at larger radius

Fast SimulationReady for Phase 1 simulations studies but take into account:

• Need understand small Fast/Full sim differences at high eta• Need to understand and tune tracker/pixel occupancies• Implement out-of-time pileup (if needed?)

Hits and TrackingFully working, but accurate results still need some work:

• Need hit position and error routine for upgrade geometry• Need to tune iterative tracking and implement quartet seeds


Past Simulation StudiesPast Simulation Studies

Much of the upgrade simulations efforts in the past were on Phase 2

Past Phase 1 simulation studies is of less interest nowUsed “Quick Approach” Phase 1 Geometry

• 4 layer upgrade BPIX but still with half and full ladders, though material was weighted for new lighter services

• 3 FPIX disk (but same FPIX disks as standard geometry)

Later used some combination of “Quick Approach” and early version of “Detailed Approach” Phase 1 Geometry

• Problems in FPIX region; BPIX layers not finalized

Many studies used CMSSW_1_8_4-like non-iterative tracking• Comparisons with the standard geometry should be will the most recent

(possible) CMSSW software - at least the iterative tracking– Also iterative tracking easier for tuning to upgrade conditions

• Many other improvements to the code in CMSSW_3_3_6 (e.g. memory usage) and bug fixes (e.g. truth particle parentage)

Next 5 slides shown just as examples of most recent past Phase 1 studies• From Feb 11 Status report given by Pratima Jindal (Tracker Week)


From Feb 11 Status Report:From Feb 11 Status Report:

Tracking Efficiency and Fakerate StudiesFast Simulation (with digis) using CMSSW_2_2_6

Phase1 geometry using realistic Phase1 disks with problems in negative eta and the quick approach for adding the 4th barrel layer (version from Oct), will update soon with new geometry description

QCD dijet events pT= 100-120 GeV, |η| < 2.5

Higher fake ratefor Phase 1for PU 100

Track reconstruction: • Using old non-iterative tracking• Standard geometry:

• triplet seeds (3-out-of-3) • Phase 1:

• triplet seeds (3-out-of-4)• Minimum of 3 hits per track • Restricted vertex search volume in TrackingTruthProducer

Requiring 6 hitsper track reduces fake rate for PU 100

John Ellison & Ferdinando Giordano



εb= 0.6 for udsg mistagrate of ~0.55% εb= 0.6 for udsg mistagrate of ~0.6%

εb= 0.6 for udsg mistagrate of ~10.0% εb= 0.6 for udsg mistagrate of ~4.0%

Pile-up 0, restricted to |eta| < 1.4

Pile-up 100,restricted to |eta| < 1.4

• Using 50 –120 GeV jets • Fastsim using CMSSW_2_2_6 • Track Counting High Efficiency algorithm

b-tagging PerformanceUsing Phase1 geometry using realistic Phase1 disks with problems in negative eta and the quick approach for adding the 4th barrel layer (version from Oct)

John Ellison & Ferdinando Giordano



Tracking Efficiency and Fakerate StudiesFull Sim using CMSSW_2_2_6 with iterative tracking and 3/4 seeding

Four 100 GeV/c muons

Using the version of FPix geometry known to have problems in negative eta (shall move to new geometry soon)

Increasing the minimum number of hits per tracks from 3 may reduce

the fake rate at high pileup ( as seen in Fast Sim with non-iterative tracking)

Carlo Civinini



Seeding Efficiency and Fakerate StudiesFull Sim using CMSSW_2_2_13

Comparing standard geometry and standard triplets (3/3) to Phase1 geometry with iterative tracking and 3/4 seeding

100 GeV/c di-muons

Using new barrel geometry from Xingtau and quick approach for FPix

16

Alessia Tricomi



Tracking and Seeding Efficiency StudiesFull Sim using CMSSW_2_2_13

comparison between No PileUp and Lumi 2*10^34 for the Phase1 geometry

100 GeV/c di-muons

using new barrel geometry from Xingtau and quick approach for FPix

17

Alessia Tricomi


Current Simulation StudiesCurrent Simulation Studies

Meeting agendaBetter to refer you to talks tomorrow:

• Redoing many of the previous studies and more with new Phase 1 geometry and with CMSSW_3_3_6


Future Plan and task ListFuture Plan and task List

Plan of work for Phase 1 Technical Proposal (Produced by V.Chiochia and M.Mannelli with input from A.Tricomi and H.Cheung)

Increased 4th Layer Radius. (Motivations: Improve seed efficiency and quality, improve Tracking and HLT performance and increase robustness, improve Tracking performance in core of high-pT jets)

– Define seeding strategy for 4 layers (pairs, triplets, quadruplets) in the framework of iterative tracking

– Plot seeding efficiency and track parameter resolution (vs eta/pT) at any iterative step and total

– Study combinatorics: seed multiplicity, timing performance, cut optimization

– Introduce luminosity-induced (readout) inefficiency in the first layer

– TIB search window and combinatorics in TIB 1/2/3

– Tracking performance in core of high-pT jets



2. Reduced innermost radius and new pixel cell size. (Motivations: Improve/extend b-jet tagging capabilities, secondary vertices, and tau reconstruction)

Compare with current 3-layer systemTrack impact parameter resolution vs momentumPrimary and secondary vertex resolution, 3D flight distance resolutionb-tagging efficiency/purityEvaluate ROC/TBM data rates

Modify readout pitch in first layer (e.g. 75100 m2) and compare to 4-layer system with standard pitch (100150 m2):

Pixel position resolution vs. impact parameterTrack impact parameter resolution vs. momentumPrimary and secondary vertex resolution, 3D flight distance resolutionb-tagging efficiency/purity

Seeding efficiency for dense environments (high pT jets, tau’s)Evaluate data ROC/TBM data rates

Repeat some task in (2) for combination of smaller radius and smaller pixel cell size

2. Priority to data rates, b-tagging performance and seeding efficiency in dense jets (various Jet pT)



Reduced material budget. (Motivations: Improve Tracking efficiency and quality, reduce nuclear interactions, electron bremsstrahlung and photon conversions)

Compare with current 3-layer systemTracking efficiency and fake rate (e.g. efficiency for pion reconstructionsNumber of photon conversions and nuclear interactions vs radiusBenchmarks of electron reconstruction

We are now starting to focus on this task list: Effort already on-going in some of the tasks but need more focus on the end product; also Phase 1 geometry only recently done and ready in CMSSW_3_3_6 • Signing-up and assigning people to tasks (please email Alessia and Harry),

as well as putting down people already working on various studies• Now milestones for end of June and end of summer for (first) results• Technical/software tasks still needed

Hit position and error for upgrade geometry/smaller pixel size Geometry variation for 4th layer with increased radius MC Production: Need pileup samples for each geometry variation (Full sim)


SummarySummary

Lots of recent effort and progress on technical tasks for Phase 1Phase 1 geometry ready for Full (and Fast) simulation in CMSSW_3_3_6

• Few technical tasks to improve simulations (especially Fast simulation)

Direct/redirect all efforts to Phase 1 Simulation StudiesHad already directed/redirected effort to Phase 1 technical tasks, now focusing on simulation studies

• We have a task-oriented simulation studies list to focus our efforts• Need to get more people working on the various simulation studies (especially

with the tight deadlines/milestones that have been set)

We still need some effort on technical tasks:• Pixel hit position and resolution routine is crucial for accurate

simulation/comparisons• Need geometry variation with increased radius for 4th layer• Need effort on MC Production (Full Simulation)• Merge/Coordinate effort with tasks from upgrade physics studies from S. Dasu• Port to CMSSW_3_5_X/CMSSW_3_6_X so we have a SL5 release

– Work only with CMSSW_3_3_6 for the summer studies/results

Simulation of the 4 Layer Pixel Upgrade System (Fermilab) (For the Tracker Upgrade Simulations...

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