efforts to improve the reconstruction of non-prompt tracks with the sid

Efforts to Improve the Reconstruction of Non-Prompt Tracks with the SiD

Lori Stevens

UCSC

ILC Simulation Reconstruction Meeting

May 15, 2007

Includes contributions from:

Tyler Rice

OutlineOutline

Tyler Rice’s efficiency and purity results Tyler Rice’s efficiency and purity results from study of Tim Nelson’s from study of Tim Nelson’s AxialBarrelTrackFinder algorithmAxialBarrelTrackFinder algorithm

Z Segmentation algorithm (ZSeg.java)Z Segmentation algorithm (ZSeg.java)

Results after implementing ZSeg.javaResults after implementing ZSeg.java

Tyler’s phi-restriction and results (including Tyler’s phi-restriction and results (including ZSeg.java implementation)ZSeg.java implementation)

DetectorDetectorpythiaZPolebbbar-0-1000_SLIC_ v1r9p3_sidaug05.slcio, without pythiaZPolebbbar-0-1000_SLIC_ v1r9p3_sidaug05.slcio, without

effects of beamsstrahlung or brehmsstrahlungeffects of beamsstrahlung or brehmsstrahlung

AxialBarrelTrackFinder1.javaAxialBarrelTrackFinder1.java

Track pattern recognition using only the 5 outer Track pattern recognition using only the 5 outer tracking layerstracking layers

Works from outside inward (VXDCheater.java Works from outside inward (VXDCheater.java has already removed hits from “prompt” tracks has already removed hits from “prompt” tracks originating within 20mm of the origin)originating within 20mm of the origin)

ABTF1 begins by using all sets of isolated hits in ABTF1 begins by using all sets of isolated hits in 3 layers to find circles that pass within 10cm of 3 layers to find circles that pass within 10cm of the interaction point (original version had 1cm)the interaction point (original version had 1cm)

When 3 seed track is found, remaining layers When 3 seed track is found, remaining layers are checked for nearby hitsare checked for nearby hits

Event and Particle RequirementsEvent and Particle Requirements

Event (“Jet Accept Test”):Event (“Jet Accept Test”): 1. Cosine of thrust angle < 0.51. Cosine of thrust angle < 0.5 2. Thrust value > 0.942. Thrust value > 0.94

““Findable” Particles:Findable” Particles: 1. Final State or Intermediate State with r 1. Final State or Intermediate State with r

origin < 400mm and path length > 500mmorigin < 400mm and path length > 500mm 2. Transverse momentum > 0.75GeV2. Transverse momentum > 0.75GeV 3. Carries a charge3. Carries a charge 4. |Cosine theta| < 0.84. |Cosine theta| < 0.8 5. Not backscatter off of the calorimeter 5. Not backscatter off of the calorimeter

Particle and Track DefinitionsParticle and Track Definitions““Found” Findable MC Particle: associated track Found” Findable MC Particle: associated track has “purity” >= 0.75 (at least 3 of 4 hits from has “purity” >= 0.75 (at least 3 of 4 hits from same MCP or at least 4 of 5 from same MCP)same MCP or at least 4 of 5 from same MCP)

““Missed” Findable MC Particle: all other findable Missed” Findable MC Particle: all other findable MC ParticlesMC Particles

Fake track: Fake track:

1. no majority MC Particle associated with track 1. no majority MC Particle associated with track

2. tracks with bad purity (too few hits from 2. tracks with bad purity (too few hits from same MCP)same MCP)

Tyler’s Results (have already been Tyler’s Results (have already been presented in Beijing)presented in Beijing)

118/1000 events passed Jet Accept Test118/1000 events passed Jet Accept Test304 total MC Particles304 total MC Particles

Efficiency:Efficiency:131 Found with 5 hits (43%)131 Found with 5 hits (43%)100 Found with 4 hits (33%)100 Found with 4 hits (33%)73 Missed (24%)73 Missed (24%)

Fake rates:Fake rates:327 Fake (326/327 are 4 hit tracks: this implies 327 Fake (326/327 are 4 hit tracks: this implies that 4 hit tracks cannot be used)that 4 hit tracks cannot be used)

Digression: Other Studies by Tyler Digression: Other Studies by Tyler (why is reconstruction efficiency not 100%?)(why is reconstruction efficiency not 100%?)

First Tyler tried requiring that particles hit each of First Tyler tried requiring that particles hit each of the 5 outer detector layers once and only oncethe 5 outer detector layers once and only once

Fewer candidate particles:Fewer candidate particles:166 Findable MC Particles (304 before 166 Findable MC Particles (304 before requirement)requirement)

Efficiency:Efficiency:113 Found with 5 hits (68% vs. 43%)113 Found with 5 hits (68% vs. 43%)25 Found with 4 hits (15% vs. 33%)25 Found with 4 hits (15% vs. 33%)28 Missed (17% vs. 24%)28 Missed (17% vs. 24%)

Tyler’s Three-Hit Seed StudyTyler’s Three-Hit Seed Study

Then Tyler also required all hits from three-hit Then Tyler also required all hits from three-hit seed tracks to be associated with the same seed tracks to be associated with the same MC Particle MC Particle

166 Findable MC Particles (304 before 166 Findable MC Particles (304 before requirement)requirement)

Efficiency:Efficiency:144 Found with 5 hits (87% vs. 43%)144 Found with 5 hits (87% vs. 43%)15 Found with 4 hits (9% vs. 33%)15 Found with 4 hits (9% vs. 33%)7 Missed (4% vs. 24%)7 Missed (4% vs. 24%)

Motivation for Z SegmentationMotivation for Z Segmentation

Improve efficiency for finding MC Particles Improve efficiency for finding MC Particles (can we clean up the 3 hit seeds?)(can we clean up the 3 hit seeds?)

Decrease number of 4 hit fake tracks: see Decrease number of 4 hit fake tracks: see if we can make 4 hit tracks useable if we can make 4 hit tracks useable

Z Segmentation Algorithm (1 of 2)Z Segmentation Algorithm (1 of 2)

ZSeg.java creates segmentation of z-axis into separate ZSeg.java creates segmentation of z-axis into separate modules (length set by user)modules (length set by user)

Algorithm is capable of offsetting individual layers, Algorithm is capable of offsetting individual layers, amount set by user (still testing)amount set by user (still testing)

ZSeg.java contains ZCheckerExt method that takes ZSeg.java contains ZCheckerExt method that takes three SimTrackerHit arguments; this method is called three SimTrackerHit arguments; this method is called from inside AxialBarrelTrackFinder1.javafrom inside AxialBarrelTrackFinder1.java

Method calculates minimum and maximum coordinates Method calculates minimum and maximum coordinates of the z module for each of the 3 hitsof the z module for each of the 3 hits

Straight lines in r-z are projected from modules in layers Straight lines in r-z are projected from modules in layers containing 1containing 1stst two hits onto layer containing 3 two hits onto layer containing 3rdrd hit hit

Z Segmentation Algorithm (2 of 2)Z Segmentation Algorithm (2 of 2)

Algorithm checks if 3Algorithm checks if 3rdrd hit is in a module consistent with hit is in a module consistent with the1st two hits the1st two hits

For now, testing consistency in 3 hit seeds only (later to For now, testing consistency in 3 hit seeds only (later to include check for 4include check for 4thth and 5 and 5thth hits) hits)

Eventually algorithm will take in a list of hits and check all Eventually algorithm will take in a list of hits and check all possible 3 hit combinations for consistency, including a possible 3 hit combinations for consistency, including a test for whether to use extrapolation or interpolation test for whether to use extrapolation or interpolation (currently using only extrapolation)(currently using only extrapolation)

Original (Tyler’s) result: only require that hits are on Original (Tyler’s) result: only require that hits are on same side in z. This is not required when using z same side in z. This is not required when using z segmentation.segmentation.

Module Projection (extrapolation)Module Projection (extrapolation)

NoteNote: No actual spacing between modules: No actual spacing between modules

Hit 1

Hit 2

Possible modules for following hits

Module Projection (interpolation)Module Projection (interpolation)

Hit 1

Hit 2

Possible modules

Note: No actual spacing between modules

Z Segmentation ResultsZ Segmentation Results

TylerTyler30cm 30cm

segmentssegments10cm 10cm



segmentssegments

# MCPs# MCPs 304304 302302 302302 302302 302302

Found Found with 5 hitswith 5 hits 131131 122122 138138 145145 148148


MissedMissed 7373 8080 6060 4848 5555

FakeFake 327327 455455 332332 267267 127127

Z Segmentation Results

0

50

100

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300

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0 0.5 1 1.5

Log base 10 of segmentation length (in cm)

N u

m b

e r

o

f

t r

a c

k s

Found: 5 hits

Found: 4 hits

Missed

Fake

Implementing ZSeg.java Implementing ZSeg.java (“preliminary” results) (“preliminary” results)

1cm

5cm10cm

30cm

Another Idea: Require Hits to be in Another Idea: Require Hits to be in Same Sector in PhiSame Sector in Phi

Recall Tyler saw that a lot of inefficiency Recall Tyler saw that a lot of inefficiency and fake tracks due to bad 3 hit seedsand fake tracks due to bad 3 hit seeds

Clean up seeds by requiring that the phi Clean up seeds by requiring that the phi coordinate of all hits must be within coordinate of all hits must be within ππ/2 of /2 of each othereach other

Also apply criterion to all hits once track is Also apply criterion to all hits once track is foundfound

Tyler’s Phi Restriction Results Tyler’s Phi Restriction Results (only require hits on same side in z)(only require hits on same side in z)

304 total MC Particles304 total MC Particles

Efficiency:Efficiency:

145 Found with 5 hits (48%)145 Found with 5 hits (48%)

112 Found with 4 hits (37%)112 Found with 4 hits (37%)

47 Missed (15%)47 Missed (15%)

Fake rates:Fake rates:

158 Fake (all 4 hit)158 Fake (all 4 hit)

Tyler’s Results: New vs. OldTyler’s Results: New vs. Old

New New resultsresults

% of % of MCPsMCPs

Old Old resultsresults

% of % of MCPsMCPs

# of MCPs# of MCPs 304304 100%100% 304304 100%100%

Found with 5 hitsFound with 5 hits 145145 48%48% 131131 43%43%Found with 4 hitsFound with 4 hits 112112 37%37% 100100 33%33%MissedMissed 4747 15%15% 7373 24%24%FakeFake 158158 327327

Z Segmentation Results Z Segmentation Results (Phi-Restricted)(Phi-Restricted)

TylerTyler30cm 30cm




segmentssegments

# MCPs# MCPs 304304 302302 302302 302302 302302



MissedMissed 4747 4747 4141 4040 4949

FakeFake 158158 202202 142142 108108 4545

Phi Restricted Z Segmentation Results

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0 0.5 1 1.5


N u

m b

e r

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t r

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k s

Found: 5 hits

Found: 4 hits

Missed

Fake

ZSeg.java with Phi RestrictionZSeg.java with Phi Restriction

1cm 5cm 10cm

30cm

Comparing Z Segmentation with Comparing Z Segmentation with and without Phi Restrictionand without Phi Restriction

30cm 30cm phi rest.phi rest. 30cm30cm 10cm10cm

phi rest.phi rest.

10cm10cm 5cm 5cm phi rest.phi rest. 5cm5cm 1cm 1cm

phi rest.phi rest. 1cm1cm

#MCPs#MCPs 302302 302302 302302 302302 302302 302302 302302 302302

Found Found with 5 hitswith 5 hits 142142 122122 147147 138138 152152 145145 152152 148148

Found Found with 4 hitswith 4 hits 113113 100100 114114 104104 110110 109109 101101 9999

MissedMissed 4747 8080 4141 6060 4040 4848 4949 5555

FakeFake 202202 455455 142142 332332 108108 267267 4545 127127

Graphs of Z Segmentation with and Graphs of Z Segmentation with and without Phi Restrictionwithout Phi Restriction

Z Segmentation Results

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0 0.5 1 1.5


N u

m b

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o f

t r

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Found: 5 hits

Found: 4 hits

Missed

Fake

Phi Restricted Z Segmentation Results

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350

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0 0.5 1 1.5


N u

m b

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Found: 5 hits

Found: 4 hits

Missed

Fake

1cm 5cm

10cm

30cm

1cm 5cm 10cm

30cm

Comments on ResultsComments on Results

Might expect 30cm segmentation to be Might expect 30cm segmentation to be worse than simply requiring all hits to be worse than simply requiring all hits to be on same side of the detectoron same side of the detector

Assumption that tracks are straight in r-z is Assumption that tracks are straight in r-z is less valid for low pTless valid for low pT

ShortcomingsShortcomings

Projection in r-zProjection in r-z will actually curve; will actually curve;

ZSeg.java treats track r-z projection as if it ZSeg.java treats track r-z projection as if it were a straight linewere a straight line

Using ZPole; qqbar at 500GeV would be Using ZPole; qqbar at 500GeV would be even more challenging. Would like to even more challenging. Would like to study but will need 500GeV qqbar with no study but will need 500GeV qqbar with no beamsstrahlung or brehmsstrahlungbeamsstrahlung or brehmsstrahlung

For the FutureFor the Future

Check for z consistency in 4Check for z consistency in 4thth and 5 and 5thth hits hits

Take in list of hits and check all possible Take in list of hits and check all possible hit combinations (including interpolation/hit combinations (including interpolation/

extrapolation check)extrapolation check)

Check validity of straight line Check validity of straight line approximation as a function of pTapproximation as a function of pT

The EndThe End

efforts to improve the reconstruction of non-prompt tracks with the sid

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