# Presentation: 099883

## Update on track reconstruction in the Near Detector

- N. Saoulidou Fermilab

- N. Saoulidou (niki@fnal.gov). Fermilab 11 - 6 - 2003

## Outline

-  Brief review of the goal & main idea.
-  Comparison between my version of the code and the existing one.
- Summary – On going work

- N. Saoulidou (niki@fnal.gov). Fermilab 11 - 6 - 2003

## Goal & Strategy

**Goal** :
- Reconstruct the muon track from the “vertex” to the spectrometer region.
**Strategy :**
- a) Assume that event slicing is already done (process only single events were things are much more clear).
- b) Consider all four different strip solutions in the spectrometer region  without assigning any kind of weight.
- c) Use the existing track reconstruction code and tune the various cuts in order to account for the specific characteristics of the Near Detector

- N. Saoulidou (niki@fnal.gov). Fermilab 11 - 6 - 2003

## Strategy cont.

**No weight assignment for the following reasons** :
- More than half of the neutrino events will occur in the spectrometer region or very close to it were any weighting scheme is actually meaningless (in the spectrometer region we will, most of the time, have four identical 2D solutions with no way of identifying the true one).
- Weighting for events that occur in the upstream region and extend to the spectrometer region will involve some kind of upstream tracking that will be extended downstream, and that is the way tracking will have to be done as well.
- No weighting is needed for events that are contained in the upstream, not plexed, region

- N. Saoulidou (niki@fnal.gov). Fermilab 11 - 6 - 2003

## Examples of reconstructed muon tracks

**Roberts Cheezy event display modified **
**Green circles:****  ****all digits in an event **
**Gray open circles :**** true MC digits**
**Black  star :  true neutrino interaction vertex**
**Blue squares :****  true muon digits. **
**Red dots :**** reconstructed and fitted 3D track.**

- N. Saoulidou (niki@fnal.gov). Fermilab 11 - 6 - 2003

## Examples of reconstructed muon tracks cont.

- N. Saoulidou (niki@fnal.gov). Fermilab 11 - 6 - 2003

## Examples of reconstructed muon tracks cont.

- N. Saoulidou (niki@fnal.gov). Fermilab 11 - 6 - 2003

## Comparison between my approach and the existing one 1.

- A very similar approach (for tracking in the Near Detector) to the one I am considering has been implemented and committed to the cvs about 2 weeks ago.
- I processed a few MC near detector events (low energy beam) with both codes and compared the results
- Unfortunately I could not process a large number of MC events with  ** the current code because it keeps crashing** when running one of my scripts.

- My approach

- Current code

- N. Saoulidou (niki@fnal.gov). Fermilab 11 - 6 - 2003

## Comparison between my approach and the existing one 2.

**Comparison between my approach and the existing one 2.**

- My approach

- Current code

- N. Saoulidou (niki@fnal.gov). Fermilab 11 - 6 - 2003

## Comparison between my approach and the existing one 3.

- My approach

- Current code

- N. Saoulidou (niki@fnal.gov). Fermilab 11 - 6 - 2003

## Comparison between my approach and the existing one 4.

**Comparison between my approach and the existing one 4.**

- My approach

- Current code

- N. Saoulidou (niki@fnal.gov). Fermilab 11 - 6 - 2003

## Quantitative results of the track reconstruction (update)

- Percentage(%) of the reconstructed muon track strips that belong to the true muon track (for 10000 Near Det. MC events), after considering
**a)** **numu CC events with the neutrino vertex up to ~ 20 plates upstream the spectrometer region (just to make sure that the event is far enough from the spectrometer region) and**
**b) the muon track to have more than 5 planes **
- The mean value of this distribution  is ~ 81%.
- The percentage of numu CC events satisfying the previous criteria were no track was reconstructed is ~ 20 %.

- N. Saoulidou (niki@fnal.gov). Fermilab 11 - 6 - 2003

## Summary &  On going work

- The results  of the track reconstruction attempt in the Near Detector are  quite reasonable.
- The overall efficiency of this code is higher than the  existing one.
- I need to further examine the reasons for some code failures.
- I would like to test Sergei’s (and the SR) fitter on the reconstructed Near Det. Tracks.

- N. Saoulidou (niki@fnal.gov). Fermilab 11 - 6 - 2003