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

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

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

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

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

Helix Parameter Calculations ω 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

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

Z0 Pull Distribution

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

(1-Purity) vs Hits

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

Efficiency vs Theta

Efficiency vs Pt

Wire View One (Rho-z) event # 130

Wire View Two (xy) event # 130

Results Purity: Tracks can be expected to be pure around 96.4+-0.2% 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.

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

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

References J. Alcaraz, Helicoidal tracks. L3 Internal Note 1666, February 18, 1995. Internation Linear Collider website. http://www.linearcollider.org/cms/