Status

1
Status Update of track reconstruction in the
Near Detector

• N. Saoulidou, Fermilab 10-3-04

2
Outline

• Summary of Corrections Modifications done so
  far (after the previous Collaboration Meeting).
• Improvement (Initial Final Results) on
• - Track reconstruction efficiency
• - Track Completeness (and Effect of Slicing)
• - Track Purity
• Summary On going work

3
Modifications Corrections on ND tracking

• Code tuning, related with how the code handles
  events occurring in the partially covered plane
  area (which is identical to the spectrometer
  region (1/5 planes instrumented) except from the
  Plex .
• Modification on the way duplicate 3D tracks
  are examined
• Initially the percentage of identical hits was
  examined for all track strips (U and V together).
• There were some cases were false 3D solutions
  existed having the correct 2D Line in one view
  and the wrong 2D Line in the other view.
• The code is now modified to examine percentage of
  identical strips in each view and keep the
  solution with the largest number of planes.
• Corrections on the plane number from which the
  Plex starts from gt 121 to gt121!
• Due to that error a few quite clear tracks were
  missed because the code was unable to reconstruct
  the correct 2D line in the U view.

4
Track Reconstruction Completeness (All tracks
with completeness gt 0)
Final
Initial

• The previous changes resulted in an increase on
  the number of reconstructed tracks (796-gt899) and
  an increase in track completeness ( 85-gt88)

5
Track Reconstruction Completeness after slicing
(All tracks with completeness gt 0)
Final
Initial

• This actually reflects the track reconstruction
  quality since it is performed after the Event
  Slicing. There is also increase on the number of
  reconstructed tracks (796-gt899) and an increase
  in track completeness ( 86-gt89)

6
Track Reconstruction Purity (All tracks with
completeness gt 0)
Final
Initial

• The increase on the number of reconstructed
  tracks (796-gt899) did not decreased (or
  increased) track purity ( 92-gt92)

7
Track Reconstruction Completeness (All Muon
tracks no cut in completeness)
Initial
Final

• The previous changes resulted in an increase on
  the number of reconstructed muon tracks
  (697-gt801) and an increase in track completeness
  ( 87-gt89)

8
Track Reconstruction Completeness after Slicing
(All Muon tracks no cut in completeness)
Initial
Final

• There is also an increase in muon track
  completeness after slicing ( 88-gt90) as
  expected

9
Track Reconstruction Purity (All Muon tracks no
cut in completeness)
Initial
Final

• The muon track purity remains basically
  unchanged _at_ 95-96

10
Track reconstruction characteristics in the ND
(Muons)
Completeness
U
V

• These plots show that
• There is a clear preference in the number of
  reconstructed muon tracks towards the fully
  instrumented ND region, which is not so pronounce
  (or not pronounce at all) for the z position of
  the neutrino vertex with respect to the Plexed
  region.
• But the track completeness is the same for all
  U V Z positions

Completeness
Z (plane )
11
Track reconstruction characteristics in the ND
(Muons) contd
Purity
U
V

• These plots show that
• There is a clear preference in the number of
  reconstructed muon tracks towards the fully
  instrumented ND region, which is not so pronounce
  (or not pronounce at all) for the z position of
  the neutrino vertex with respect to the Plexed
  region.
• But the track purity is the same for all U V Z
  positions

Purity
Z (plane )
12
Track reconstruction characteristics in the ND
(Muon Momentum )
True Muon Momentum (reconstructed muons black,
all muons red)
Difference between true and reconstructed muon
momentum

• Most of the muon tracks that are not
  reconstructed are with momentum below 1 GeV
  (these are in principle more sensitive to ND
  geometry peculiarities)
• The resolution of the muon track momentum
  reconstruction is 10 (for the majority of the
  tracks) with a clear asymmetry at negative
  values (mean _at_ -4)

13
Muon track reconstruction efficiencies

• Muon track reconstruction efficiency is 86 for
  
• z lt plane 115 (5 planes upstream the plexed
  region)
• Number of true muon planes gt 5 (in order to be
  able to reconstruct 2D lines in each view)
• No Cuts in U and V neutrino vertex position
• Muon track reconstruction efficiency is 92 for
  
• z lt plane 115 (5 planes upstream the plexed
  region)
• Number of true muon planes gt 5 (in order to be
  able to reconstruct 2D lines in each view)
• U neutrino vertex gt 0 and V neutrino vertex lt 0
  (fully instrumented region)

14
Summary On going work

• Making corrections and additions to the ND
  tracking code the track reconstruction efficiency
  and all track characteristics (completeness
  purity) have been improved.
• The 92 of track reconstruction efficiency in
  the fully instrumented region of the ND, the 90
  of track completeness and 95 of track purity
  are quite satisfactory and I think the ND
  tracking code is in quite good shape.
• From now on I will focus more in ND track fitting
  trying to improve mostly timing issues.