DT Local Reco - INFN Sezione di Padovalacaprar/talks/Joint_DT-DPG... · 2008. 4. 3. · DT Local Reco Stefano Lacaprara INFN LNL Joint DT-DPG MuonDet Pyhs CERN, 3-Apr-2008. Status

Status od LocalReco open issues Conclusion

DT Local Reco

Stefano Lacaprara

INFN LNL

Joint DT-DPG MuonDet PyhsCERN, 3-Apr-2008


Outline

1 Status od LocalRecoHitsSegments

2 open issuesPossible solution

3 Conclusion


Note on Local reco

A CMS Note on current status of DT Local Reco (Hit andSegment) has been submitted

Reference point for studies on MC simulation

Pending for approval


Hits

Hit reco status

Hit reconstruction is stable since some time

Different reco algo are available:

one based on parametrized time-to-distance relationship,taking into account B field and impact angle, from detailedGARFIELD studies. Optimum results on MC studies, used forNotea constant drift velocity, used for Cosmic Data reconstruction

Resolution µm for different wheel at following step ofreconstruction

Superlayer type r-φ r-z, W 0 r-z, W ±1 r-z, W ±2Step 1 237 250 271 308Step 2 231 250 271 305Step 3 207 196 210 228


Hits

Hit resolution r -φprojection, different wheel

Entries 3562444

/ ndf 2χ 4.70e+04 / 27

Constant 399± 5.66e+05

Mean 1.30e-05± -2.36e-03

Sigma 1.07e-05± 2.38e-02

)sim-dreco

(d-0.15 -0.1 -0.05 0 0.05 0.1 0.15

# e

ve

nts

0

100

200

300

400

500

600

310×Entries 3562444

/ ndf 2χ 4.70e+04 / 27


Mean 1.30e-05± -2.36e-03

Sigma 1.07e-05± 2.38e-02

Entries 3405697

/ ndf 2χ 5.59e+04 / 27


Mean 1.29e-05± 9.82e-04

Sigma 1.06e-05± 2.32e-02

)sim-dreco

(d-0.15 -0.1 -0.05 0 0.05 0.1 0.15

# e

ve

nts

0

100

200

300

400

500

600310×

Entries 3405697

/ ndf 2χ 5.59e+04 / 27


Mean 1.29e-05± 9.82e-04

Sigma 1.06e-05± 2.32e-02

Entries 3447732

/ ndf 2χ 5.70e+04 / 27


Mean 1.15e-05± -2.39e-04

Sigma 9.58e-06± 2.09e-02

)sim-dreco

(d-0.15 -0.1 -0.05 0 0.05 0.1 0.15

# e

ve

nts

0

100

200

300

400

500

600

310×Entries 3447732

/ ndf 2χ 5.70e+04 / 27


Mean 1.15e-05± -2.39e-04

Sigma 9.58e-06± 2.09e-02

(cm) (cm) (cm)


Hits

Hit resolution r -φprojection vs impact angle

track angle (rad)0 0.1 0.2 0.3 0.4 0.5 0.6

) (cm

)sim-d

reco

(d

-0.2

-0.15

-0.1

-0.05

-0

0.05

0.1

0.15

0.2

track angle (rad)0 0.1 0.2 0.3 0.4 0.5 0.6

) (cm

)sim-d

reco

(d

-0.2

-0.15

-0.1

-0.05

-0

0.05

0.1

0.15

0.2

track angle (rad)0 0.1 0.2 0.3 0.4 0.5 0.6

) (cm

)sim-d

reco

(d

-0.2

-0.15

-0.1

-0.05

-0

0.05

0.1

0.15

0.2

After step 2, when impact angle effect is taken into account byreconstruction SL segments, angle effect is removed


Hits

Hit resolution r -φprojection vs distance from FE

distance from FE (cm)0 50 100 150 200 250 300 350 400

) (c

m)

sim

-dre

co(d

-0.2

-0.15

-0.1

-0.05

-0

0.05

0.1

0.15

0.2


) (c

m)

sim

-dre

co(d

-0.2

-0.15

-0.1

-0.05

-0

0.05

0.1

0.15

0.2


) (c

m)

sim

-dre

co(d

-0.2

-0.15

-0.1

-0.05

-0

0.05

0.1

0.15

0.2

After step 3, when coordinate along the wire is reconstructed with3D segments, sistematic shift due to wire propagation time iscured.


Hits

Hit Pulls r -φand r -z

Entries 3562444

/ ndf 2χ 3.47e+04 / 97


Mean 0.0005± -0.0995

Sigma 0.000± 0.997

recoσ)/sim-dreco

(d-5 -4 -3 -2 -1 0 1 2 3 4 5

# ev

ents

0

20

40

60

80

100

120

140

310×Entries 3562444

/ ndf 2χ 3.47e+04 / 97


Mean 0.0005± -0.0995

Sigma 0.000± 0.997

Entries 3405697

/ ndf 2χ 4.03e+04 / 97


Mean 0.0006± 0.0425

Sigma 0.000± 0.996

recoσ)/sim-dreco

(d-5 -4 -3 -2 -1 0 1 2 3 4 5

# ev

ents

0

20

40

60

80

100

120

140

310×Entries 3405697

/ ndf 2χ 4.03e+04 / 97


Mean 0.0006± 0.0425

Sigma 0.000± 0.996

Entries 3447732

/ ndf 2χ 3.75e+04 / 97


Mean 0.0005± -0.0109

Sigma 0.000± 0.968

recoσ)/sim-dreco

(d-5 -4 -3 -2 -1 0 1 2 3 4 5

# ev

ents

0

20

40

60

80

100

120

140

310×Entries 3447732

/ ndf 2χ 3.75e+04 / 97


Mean 0.0005± -0.0109

Sigma 0.000± 0.968

Entries 1378880

/ ndf 2χ 1.34e+04 / 97


Mean 0.00091± 0.00854

Sigma 0.00± 1.03

recoσ)/sim-dreco

(d-5 -4 -3 -2 -1 0 1 2 3 4 5

# ev

ents

0

10000

20000

30000

40000

50000

Entries 1378880

/ ndf 2χ 1.34e+04 / 97


Mean 0.00091± 0.00854

Sigma 0.00± 1.03

Entries 1325584

/ ndf 2χ 1.28e+04 / 97


Mean 0.0009± 0.0132

Sigma 0.00± 1.04

recoσ)/sim-dreco

(d-5 -4 -3 -2 -1 0 1 2 3 4 5

# ev

ents

0

10000

20000

30000

40000

50000

Entries 1325584

/ ndf 2χ 1.28e+04 / 97


Mean 0.0009± 0.0132

Sigma 0.00± 1.04

Entries 1325584

/ ndf 2χ 1.68e+04 / 97


Mean 0.0009± -0.0174

Sigma 0.00± 1.02

recoσ)/sim-dreco

(d-5 -4 -3 -2 -1 0 1 2 3 4 5

# ev

ents

0

10000

20000

30000

40000

50000

Entries 1325584

/ ndf 2χ 1.68e+04 / 97


Mean 0.0009± -0.0174

Sigma 0.00± 1.02

Pull under control at all three steps


Hits

Hit residuals for param and constant drift time

Distance from wire (cm)0 0.5 1 1.5 2 2.5

(cm

)si

m -

dre

cod

-0.4

-0.2

0

0.2

0.4

Entries 27874Entries 27874

Distance from wire (cm)0 0.5 1 1.5 2 2.5

(cm

)si

m -

dre

cod

-0.4

-0.2

0

0.2

0.4

Entries 27879Entries 27879

Of course, cell non lineary affects constant drift time reconstruction


Segments

Segment reco status

Segment reconstruction is stable as well;

still some open issues (see later)

Different reco algo are available/proposed:

Standard combinatorics reconstruction (described in note)Addition to compute vdrift and t0 from the fit itself (Anna M.)MeanTimer tecnique: being developed for low β particlestudies (Piotr T.)noDrift fast reco using just wire position (Martijn M.)

3 steps reconstruction:1 pattern reco for hits, with L/R ambiguity2 refit using track angle3 refit with B and position along wire known by combinig two SL


Segments

Segment reco position resolution


Mean 1.56e-05± 3.82e-05

Sigma 0.00002± 0.00882

(cm)sim-xrecx-0.15 -0.1 -0.05 0 0.05 0.1 0.150

5000

10000

15000

20000

25000

30000


Mean 1.56e-05± 3.82e-05

Sigma 0.00002± 0.00882


Mean 0.000021± 0.000152

Sigma 0.0000± 0.0123

(cm)sim

-yrec

y-0.1 -0.05 0 0.05 0.10

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

22000

24000 Constant 50± 2.17e+04

Mean 0.000021± 0.000152

Sigma 0.0000± 0.0123


Segments

Segment reco angle resolution


Mean 1.27e-06± 3.45e-07

Sigma 0.000001± 0.000715

(rad)simxα-rec

xα-0.015 -0.01 -0.005 0 0.005 0.01 0.0150

5000

10000

15000

20000

25000

30000Constant 68± 2.65e+04

Mean 1.27e-06± 3.45e-07

Sigma 0.000001± 0.000715


Mean 1.04e-05± 1.05e-05

Sigma 0.00001± 0.00597

(rad)simyα-rec

yα-0.1-0.08-0.06-0.04-0.02 0 0.020.040.060.08 0.10

5000

10000

15000

20000

25000Constant 54± 2.21e+04

Mean 1.04e-05± 1.05e-05

Sigma 0.00001± 0.00597


Segments

Segment reco Pulls


Mean 0.0020± 0.0039

Sigma 0.0± 1.1

σ)sim-xrec

(x-5 -4 -3 -2 -1 0 1 2 3 4 50

1000

2000

3000

4000

5000

6000

7000

8000

9000 Constant 19± 8.2e+03

Mean 0.0020± 0.0039

Sigma 0.0± 1.1


Mean 0.002± 0.009

Sigma 0.0± 1.1

σ)/sim

-yrec

(y-5 -4 -3 -2 -1 0 1 2 3 4 50

1000

2000

3000

4000

5000

6000

7000

8000


Mean 0.002± 0.009

Sigma 0.0± 1.1


Mean 0.00191± 0.00091

Sigma 0.0± 1

σ)/simxα-rec

xα(-5 -4 -3 -2 -1 0 1 2 3 4 50

1000

2000

3000

4000

5000

6000

7000 Constant 15± 6.4e+03

Mean 0.00191± 0.00091

Sigma 0.0± 1

Constant 10± 3e+03

Mean 0.0029± 0.0005

Sigma 0.0± 1.1

σ)/simyα-rec

yα(-5 -4 -3 -2 -1 0 1 2 3 4 50

500

1000

1500

2000

2500

3000

Constant 10± 3e+03

Mean 0.0029± 0.0005

Sigma 0.0± 1.1


Segments

Segment reco Efficiency

x (cm)-60 -40 -20 0 20 40 60 80 100 120

∈

0.8

0.85

0.9

0.95

1

1.05

Eff

Full chamber

Excluding chamber edge

y (cm)-150 -100 -50 0 50

∈

0.8

0.85

0.9

0.95

1

1.05

Eff

Full chamber


0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

x (cm)-50 0 50 100 150

y (

cm

)

-140

-120

-100

-80

-60

-40

-20

0

20

40

x (cm)-150 -100 -50 0 50

∈

0.86

0.88

0.9

0.92

0.94

0.96

0.98

1

1.02

1.04

Eff

Full chamber


y (cm)-100 -50 0 50 100

∈

0.8

0.85

0.9

0.95

1

1.05

Eff

Full chamber


0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

x (cm)-150 -100 -50 0 50 100

y (

cm

)

-120

-100

-80

-60

-40

-20

0

20

40

60

80

x (cm)-150 -100 -50 0 50 100 150

∈

0.8

0.85

0.9

0.95

1

1.05

Eff

Full chamber


y (cm)-50 0 50 100 150

∈

0.8

0.85

0.9

0.95

1

1.05

Eff

Full chamber


0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

x (cm)-150 -100 -50 0 50 100 150

y (

cm

)

-50

0

50

100

150

x (cm)-100 -50 0 50 100 150 200

∈

0.8

0.85

0.9

0.95

1

1.05

Eff

Full chamber


y (cm)-150 -100 -50 0 50 100 150

∈0.8

0.85

0.9

0.95

1

1.05

Eff

Full chamber


0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

x (cm)-50 0 50 100 150 200 250

y (

cm

)

-150

-100

-50

0

50

100

150

Estimated from GREN Data (not MC) by using a sandwitch ofchambers


Outline



3 Conclusion


Still problem in pattern recongition for r -zSL, where,sometime, a wrong pattern is selectd resulting in wrongdirection of segments

Affects seed generation as well as StandAlone/Globalreconstruction

If a “wrong” r -zsegment is used, other correct segment canbe rejected as incompatible with track candidate

More serius on Cosmic data than on p − p (MC) data due tolack of IP constraint

Code optimization for speed and memory footprint

Task force

A dedicated task force (4 people) is being setup in order to studyand possible solve these problems.


Possible solution

Possible Solution being discussed

The problem is not in pattern reco (which does find correctsegments) but in segment cleaning, where sometime we rejectthe right segments and retain the bad onedifficult to fine tune cleaner...

in r -zthe track are straight!Try a reconstruction using simultaneously more than one station inorder to increase the lever arm

Prototype algo using hits from layers of different stationfirst results are promising but there are several issues to beaddressed

which chambers to considercombinatoric increase and can be problematicshow to use these multi SL segments in track reconstruction


Possible solution

Other approach

reconstruct clusters of hits in each SL

can be useful also for high Pt Muons with large showering,where segment parretrn reco is hard/impossible

Use hits from a SL in a station (as now) plus a clusters “largehit” from close by SL in other station

much less combinatorics, still longer lever arm, avoid problemin tuning error for track propagation in magnet-joke

can reuse much of the current code, need a “clusterer” for DT

...


Outline



3 Conclusion


Conclusion

Reconstruction Status

hit and segment reconstruction is rather stable

other recon algos are beeing developed and are under test

still issues on r -zreconstruction, important mostly for cosmicreconstruction

dedicated task force to cope with these issues setup: somepossible smart idea are available.

Documents

DT Local Reco - INFN Sezione di Padovalacaprar/talks/Joint_DT-DPG... · 2008. 4. 3. · DT Local Reco Stefano Lacaprara INFN LNL Joint DT-DPG MuonDet Pyhs CERN, 3-Apr-2008. Status