Reco Tracks Revisited UCSD meeting November 2 2007

Reco. Tracks Revisited UCSD meeting November 2, 2007 R. Kelley

Reco. Tracks Revisited • A quick word on association by hits • Clear up a question on the low pt cut-off RS vs CTF • Charge of reco. Tracks • The resolutions plots revisited • CMSSW 1_6_X – Ran over ~5 k events from TTbar release validation sample(/Rel. Val. TTbar/CMSSW_1_6_0 -Rel. Val 1189470628/GEN-SIM-DIGI-RECO ) UCSD meeting November 2, 2007 2 R. Kelley

Association by Hits • Definition of association by hits: A matched reco. Track is a reco. Track that has 50% or more of its tracker hits overlap the simulated hits from a sim. Track. UCSD meeting November 2, 2007 3 R. Kelley

Fraction of Shared Hits Note: Most of the associated reco. Tracks share 100% of their hits with their corresponding sim. Track. UCSD meeting November 2, 2007 4 R. Kelley

RS vs CTF Last time there was some confusion on why it seemed that RS reconstructed many less tracks than CTF UCSD meeting November 2, 2007 5 R. Kelley

A Quick and Dirty on RS Tracks (Kevin Burkett) UCSD meeting November 2, 2007 6 R. Kelley

RS vs CTF • This shows clearly that the RS algorithm has a higher minimum seed p. T value (≈1. 5 Ge. V). • The ‘bleed off’ is due to misestimate of p. T from only a few [seed] hits. • So in order to be fair to RS, we should make a minimum p. T cut. UCSD meeting November 2, 2007 7 R. Kelley

Efficiency (p. T > 3. 0 Ge. V) UCSD meeting November 2, 2007 8 R. Kelley

Charge Asymmetry • There seems to be less negatively charged reco. Tracks than positive. Why? + charge - charge UCSD meeting November 2, 2007 9 R. Kelley

Charge Asymmetry • One possible explanation is that π+ ≈ 20 mb reacts differently than π- at lower energies. • some of the charged tracks are never reconstructed after ≈ 60 mb they react with the material. • Since σπ-p > σπ+p, more negatively charged tracks are lost in the material. UCSD meeting November 2, 2007 10 1 Ge. V R. Kelley

Resolution Revisited • • • Resolution = Reco. Track – Sim. Track (denoted by δ) All these plots were made with CTF tracks and associated by Hits. There seems to be a similar trend in variables defined in the r-z plane. – An initial improvement in resolution followed by a steady decrease. UCSD meeting November 2, 2007 11 R. Kelley

Steady Rise • Touch light affect: as you move in |η|, the distance from the first measurement point to the point of closest approach increases. • This causes this point to be reconstructed with less precision which is responsible for the steady rise in the resolution plots for variables defined in the r-z plane. • The r-z plane reco variables to be less precise as |η| increases. UCSD meeting November 2, 2007 12 R. Kelley

Small |η| improvement (Charge Sharing) • The improvement for small |η| can be seen from considering charge sharing. UCSD meeting November 2, 2007 13 R. Kelley

More Resolution Plots • Consider the plots in the r-φ plane. • They suffer from a similar rise in resolution for increasing |η|. • They do not have the improvement at low |η|. UCSD meeting November 2, 2007 14 R. Kelley

Tracker Geometry • This can be explained by looking at the geometry of the tracker. UCSD meeting November 2, 2007 15 R. Kelley

R-Z plane vs R-Phi Plane z L 1 L 2 UCSD meeting November 2, 2007 16 R. Kelley

What About p. T? • There is an additional affect for the pt measurement to multiple scattering. UCSD meeting November 2, 2007 17 R. Kelley

Accounting for the Effects Total Affect UCSD meeting November 2, 2007 18 R. Kelley

Pull Distributions • Pull = resolution / error • Since the pull distribution depends also on error, it is a bit more complicated since the error determination may not be fully accurate. • We’ll get back to you on these. UCSD meeting November 2, 2007 19 R. Kelley

Pull in r-z Plane UCSD meeting November 2, 2007 20 R. Kelley

Pull in r-φ Plane UCSD meeting November 2, 2007 21 R. Kelley

Back up UCSD meeting November 2, 2007 22 R. Kelley

Combinatorial. Track. Finder (CTF) (Kevin Burkett) UCSD meeting November 2, 2007 23 R. Kelley

Combinatorial. Track. Finder (CTF) (Kevin Burkett) UCSD meeting November 2, 2007 24 R. Kelley

Combinatorial. Track. Finder (CTF) (Kevin Burkett) UCSD meeting November 2, 2007 25 R. Kelley

Combinatorial. Track. Finder (CTF) (Kevin Burkett) UCSD meeting November 2, 2007 26 R. Kelley

Road. Search Tracking (Kevin Burkett) UCSD meeting November 2, 2007 27 R. Kelley

A Quick and Dirty on RS Tracks (Kevin Burkett) UCSD meeting November 2, 2007 28 R. Kelley

Road. Search Tracking (Kevin Burkett) • Above p. T~5 Ge. V, efficiencies about equal. • The overall inefficiency dominated below 2 Ge. V. UCSD meeting November 2, 2007 29 R. Kelley

Efficiency (p. T > 3. 0 Ge. V) UCSD meeting November 2, 2007 30 R. Kelley

design of the tracking system (Boris) Some formulae stolen from books. The L. Rolandi’s one on your shelf contains them (“Particle Detection with Drift Chambers” by Blum and Rolandi) UCSD meeting November 2, 2007 31 R. Kelley

design of the tracking system (Boris) UCSD meeting November 2, 2007 32 R. Kelley