1. Atlantis and the Inner Detector
Gary Taylor (UCSC) 7/3/2003
Outline
Tracking in the inner detector at design luminosity
Reconstruction of secondary vertices
Association of ID tracks to the calorimeters
Association of ID tracks to muon tracks
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 z r

12. Clusters from a single module
Ghost hits

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

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

15. 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

16. 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)

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 in Inner detector (near term)
add tracks from iPatRec
add reconstructed track-to-hit association
improve presentation of silicon strip data
add histogram to search for high pt tracks in TRT

20. Conclusions
many aspects of the reconstruction may be checked using Atlantis
much more available soon
followed by new public release
users and their feedback/requests are very welcome
tutorial foreseen during May software workshop
happy to help produce event displays for user presentations
Special thanks to
Jon Couchman (Access to data from Athena –JiveXML)
Hans Drevermann (Ideas and advice)