1. Silicon Detector Design Study Tracking Analysis Program for the International Linear Collider
Pelham Keahey
Richard Partridge
SULI 2008

2. International Linear Collider (ILC)
Graphic courtesy of ILC / form one visual communication

3. SiD Detector Concept Design
Graphic courtesy of Norman Graf, SLAC/Sandbox Studio

4. Analysis Program Objectives
Develop a program(s) to:
Display and analyze pull distributions of five helix parameters
Track purity and the fake track rate
Track finding Efficiency

5. Helix Parameters ω - curvature of the track
δ -distance of closest approach (dca)
Ф0 -azimuthmal angle of the momentum at the dca
tan λ -dz/ds, slope in the sz plane
z0 -z position at the dca

6. Helix Parameter Calculationsω δ
xc = x + R sin f
yc = y - R cos f
δ = R - (xc2 + yc2)1/2 Ф0
tan λ
tan λ = pz / (px2 + py2)1/2 z0
z = z0 + s tanl

7. Pull Distributions Error is different per fitted helix (track)
Tracks will go through different part of the detector
Multiple scattering
How many hits

8. Z0 Pull Distribution

9. Purity—FakeTrack Rate
Purity is taking the hits used to create a track and determining how many of those hits are actually from the MCParticle’s path being fitted
For the Z0 events the tracking program produced no fake tracks. Fake Tracks are defined as having a purity less than 0.5

10. (1-Purity) vs Hits

11. Efficiency
Efficiency is calculated by taking the number of found tracks divided by the number of tracks that could have been found
The simulation is currently setup to ignore certain particles
Pt<1.1 GeV (particle that doesn’t enter the calorimeter)
Also if z0 > 9 mm and a δ > 9 mm
7 hits minimum

12. Efficiency vs Theta

13. Efficiency vs Pt

14. Wire View One (Rho-z) event # 130

15. Wire View Two (xy) event # 130

16. Results
Purity: Tracks can be expected to be pure around % of the time, depending on event.
In the Z0 we found no tracks below the 0.5 purity margin.
Efficiency: During the same event 98.6±0.1% of the findable tracks were found.

17. Future Work As the detector evolves, different designs can be tested
Different and more complicated events can be run

18. Acknowledgements Advisor: Richard Partridge
life saving help: Cosmin Deaconu
Everyone at SLAC
DOE

19. References
J. Alcaraz, Helicoidal tracks. L3 Internal Note 1666, February 18, 1995.
Internation Linear Collider website.