1. Visual Checks of the Reconstruction using Atlantis
Gary Taylor (UCSC) 4/3/2003
Outline
Tracking in the inner detector at design luminosity
Reconstruction of secondary vertices
Calorimeter clustering and jets
Tracking in the muon system
Future plans

2. Check track reconstruction in difficult design luminosity event
Selected event has two high pt (>560GeV) jets ( DC1dataset 2045)
Luminosity
Silicon space points ,000
TRT hits ,000
Reconstructed tracks ,200
Reconstructed in minutes

3. 2D projections of Inner Detector data not very useful at design luminosity
(TRT -ve barrel only)

4. Explanation of the fh and V-Plot projections
r = rMax
V-Plot
Draw each space point twice at
F,h+k*(r-rMax)
and
F,h-k*(r-rMax)
3D information
For tracks can judge f h
pt (slope of V arms)
charge ( L -ve
V +ve) f
low p, -ve
r = 2 cm h
Distorted V’s
track not from IP
high p, +ve

5. V-Plot silicon space points
Fh calorimeters

6. Filtering of space points available inside Atlantis
Filter space points with a histogram based technique which selects hits consistent with tracks originating from the primary vertex.
Time = 1 sec/event
ATLAS note in preparation

7. Filtered hits xKalman tracks True tracks
225 GeV
34 tracks
410 GeV
20 tracks
165 GeV
28 tracks
270 GeV

8. Tracks lost in core of central jet
Unreconstructed
true tracks
Unused filtered hits
… and true tracks

9. Lost tracks in forward jet True tracks not reconstructed
All unused filtered hits
Good unused filtered hits on true tracks

10. Zoom next track feature – allows easy checking of tracking
True tracks – association not yet available for reconstructed

11. Clusters from Silicon Strips (work in progress)
stereo clusters
track
space point
rf clusters
Need … cluster-to-track association
(stereo clusters wrong in 6.0.0!) z r

12. Identifying secondary vertices
Look for a group of nearby kinked V’s in the VPlot
True tracks
Reconstructed tracks D B

13. Reconstructed and simulated secondary vertices in XY plane (t-bln)
3s error
ellipse
Primary
Reconstructed tracks
True tracks

14. Secondary vertex region best displayed in abstract 3D Box
Ellipses
represent
track
error (1s)
Plane
containing
primary
vertex
Plane
containing
secondary
vertex
secondary
vertex
primary
vertex

15. Single electron – 30 GeV pT (DC1)
LAr Presampler
Pt=29.3 GeV
E =31.2 GeV
Cell geometry
LAr Layer 2
LAr Layer 3
LAr Layer 1
Track
(enters LAr here)
Area a E
Island (guides eye)

16. Cell clustering and Jet reconstruction – AtlFast (DC1- QCD event)
Details of cell
clustering
Cells coloured by cluster (Area a E)
Jet (Area a E) ?
E= 13 GeV
SE= 347 GeV
Bug ?

17. Muon tracking with Moore – work in progress
Need to follow muon tracks in magnetic field
MDT
RPC

18. V-Plot allows comparison
Comparison of muon and inner detector track fits f
p = 28 GeV
Dp = 5 GeV
Df = 1.5 deg
Dh = 0.02
muon
tracks
Inner detector
tracks
p = 25 GeV
Dp = 4 GeV
Df = 1 deg
Dh = 0.01
V-Plot allows comparison
of f, h and pt h

19. Future plans (near term)
Dependent on Athena
add tracks from iPatRec
add reconstructed track-to-hit association
follow Moore tracks in B field
add Moore track-to-hit association
add data from CSC’s
fully implement data from AtlFast
Independent of Athena
move to latest muon geometry
improve display of calorimeters (esp FCAL and ITC)

20. Conclusions
many aspects of the reconstruction may be checked using Atlantis
much more available soon (Athena stability permitting)
followed by new public release
users and their feedback/requests are very welcome
Special thanks to
Jon Couchman (Access to data from Athena –JiveXML)
Hans Drevermann (Ideas and advice)