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

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

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

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 4

Helix Parameters • • • • • ω - curvature of the track δ -distance of closest approach (dca) Ф 0 -azimuthmal angle of the momentum at the dca tan λ -dz/ds, slope in the sz plane z 0 -z position at the dca 5

• ω • δ Helix Parameter Calculations • • • Ф 0 tan λ z0  = 1

R

= .

0003

p

 

B z

sin(   )

q

x c y c δ = x + R sin f = y R cos f = R - (x c 2 + y c 2 ) 1/2 f 0 = arctan( -

x c y c

) tan λ = p z / ( p x 2 + p y 2 ) 1/2

z

=

z

0 +

s

tan l 6

Pull Distributions (

FittedValu e

-

Simulation Value

)

FittedErro r

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

Z 0 Pull Distribution 8

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 Z 0 events the tracking program produced no fake tracks. Fake Tracks are defined as having a purity less than 0.5

9

(1-Purity) vs Hits 10

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 z 0 > 9 mm and a δ > 9 mm 7 hits minimum 11

Efficiency vs Theta 12

Efficiency vs P t 13

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

Wire View Two (xy) event # 130 15

Results • • • Purity: Tracks can be expected to be pure around 96.4+-0.2% of the time, depending on event.

In the Z 0 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.

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

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

References J. Alcaraz, Helicoidal tracks. L3 Internal Note 1666, February 18, 1995.

Internation Linear Collider website. http://www.linearcollider.org/cms/ 19