Kalman fit for phenix central arms
Download
1 / 13

Kalman Fit For PHENIX Central Arms - PowerPoint PPT Presentation


  • 76 Views
  • Uploaded on

Kalman Fit For PHENIX Central Arms. Evolution of Fit Formalism What is the Kalman Fit? New formalism for non-linear measurement matrix Results for Run-3 dAu Mass 2 resolution for p/pbar Simulation results for Run-4 configuration Improved momentum resolution at high p T Application to SVX

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Kalman Fit For PHENIX Central Arms' - perry-sloan


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Kalman fit for phenix central arms
Kalman Fit For PHENIX Central Arms

  • Evolution of Fit Formalism

    • What is the Kalman Fit?

      • New formalism for non-linear measurement matrix

    • Results for Run-3 dAu

      • Mass2 resolution for p/pbar

    • Simulation results for Run-4 configuration

      • Improved momentum resolution at high pT

    • Application to SVX

      • Measurement of displaced vertices

J. Lajoie - Kalman Fit for PHENIX


The kalman filter
The Kalman Filter

  • General Introduction

    • …goes here

J. Lajoie - Kalman Fit for PHENIX


What can we hope for
What can we hope for?

Very old MC study – assumed 150um TEC resolution and observed

poor momentum for standard reconstruction. Not much

Improvement below 5 GeV/c, ~x3 improvement at 20GeV/c.

Just adding PC’s gives modest improvement (west arm).

J. Lajoie - Kalman Fit for PHENIX


Application to run 3 dau
Application to Run-3 dAu

  • Run 69502

    • dAu chosen as a start to avoid hit association issues

    • On everybody’s “good run” list

    • Good TEC efficiency in sectors 2,3 (TOF)

    • Reconstructed and fit 190 file segments

    • Kalman uses DC X, UV hits, PC1, and TEC

    • UV hits fit only in z, filtered at 2.5 sigma

    • Magnetic field scaled up by 1.7%

  • Examine fit systematics…

J. Lajoie - Kalman Fit for PHENIX


Time to run kalman filter
Time to Run Kalman Filter

J. Lajoie - Kalman Fit for PHENIX


Chi square distributions
Chi-Square Distributions

Not a true chi-square per d.o.f – just the total chi-square divided by the

of contributing detector hits.

J. Lajoie - Kalman Fit for PHENIX


Tec residuals
TEC “residuals”

Look at TEC residuals for sectors 2,3 (TOF coverage) for “in” point

(TEC “out” point is similar)

Red: before Kalman Fit Blue: after Kalman Fit

Number of tracks

Number of tracks

Dj (radians)

Dj (radians)

The track is “pulled” to the TEC hits by the fit.

J. Lajoie - Kalman Fit for PHENIX


Run 3 dau p pbar mass 2
Run 3 dAu – p/pbar mass2

Good DC tracks, with associated TOF, PC3 hits and TEC track.

pT>2.0 GeV/c

Kalman Fit

(DC+PC1+TEC)

Standard PHENIX

Number of tracks

Very small effect (if any), but at “low” pT.

J. Lajoie - Kalman Fit for PHENIX


Momentum distribution
Momentum Distribution

Momentum distribution for all tracks with associated TEC track:

Red: before Kalman Fit

Blue: after Kalman Fit

Number of tracks

pT (GeV/c)

Softer slope for distribution after Kalman fit, consistent with improved resolution.

J. Lajoie - Kalman Fit for PHENIX


Run 4 simulation results
Run-4 Simulation Results

  • Larger magnetic field (++ configuration)

    • More bend, better resolution

      • Kalman won’t help as much until higher pT

    • Single pion events in pisa

      • No decays, hadronic interactions

      • Examine ptot=2,5,10 and 20 GeV/c

      • East Arm:

        • Fit DC+PC1+TEC

      • West Arm

        • Fit DC+PC1+PC2+PC3

        • Can Kalman help in Run-4?

J. Lajoie - Kalman Fit for PHENIX


Example 20 gev c p east arm
Example: 20 GeV/c p+ (East Arm)

Kalman

CGL

Almost a factor of two

improvement in resolution!

Number of tracks

p (GeV/c)

p (GeV/c)

J. Lajoie - Kalman Fit for PHENIX


Example 20 gev c p west arm
Example: 20 GeV/c p+ (West Arm)

Kalman

CGL

If anything the resolution

got a little worse!

Number of tracks

p (GeV/c)

p (GeV/c)

J. Lajoie - Kalman Fit for PHENIX


What s going on in the west
What’s going on in the West?

  • No resolution improvement with DC+PC1/2/3

    • Resolution worsens a little (!)

      • Probably due to Kalman errors not tuned to MC

      • Assuming errors too small builds in fluctuations

    • Consistent with PC phi error being larger than “projection” error

      • Little information added from additional hits

    • No help for Run-4!

J. Lajoie - Kalman Fit for PHENIX


ad