sPHENIX tracking discussion

[Hugo Pereira Da Costa <hugo.pereira-da-costa AT cea.fr>]

Hi Tony,

if you feel like adding more entropy to the comparison, you could also try truth track finding plus either genfit or acts fit.

My recollection is that truth track finding + genfit is very close to 2).

I have not ran truth track finding + acts recently (last time I tried it gave about 80MeV/c2 resolution, but that might have been before the post MDC regressions.

Hugo

On 5/24/2021 1:32 PM, Anthony Frawley via sPHENIX-tracking-l wrote:

        ,Hi All,
      
        
      
      
        I realized that I said something that is wrong at the meeting
        this morning, when we were discussing the onset of poorer Y(1S)
        mass resolution from our tracking code. Here is the correction.
      
        
      
      
        The attached slides (made last week) show the Y(1S) mass
        resolution from our current code, obtained with different
        tracking options. In all cases, truth vertexing was used. Normal
        Acts chain seeding consists of PHTpcTracker + TPC tracklet
        vertex association + Si track seeding + truth vertexing + TPC-Si
        track matching. 
      
      
        
      
      
        The results are:
      
        
      
      
        1) Normal Acts chain seeding + Acts track
        fit:                              95.0 +/- 2.6 MeV (used to be ~
        85 MeV)
      
      
        2) Genfit track propagation + Genfit track
        fitting:                       73.8 +/- 1.7 MeV
      
        3) Normal Acts chain seeding + Genfit final fit                
                    81.3 +/- 1.4 MeV
      
        4) Normal Acts chain seeding + Acts fit + Genfit final
        fit:           82.9 +/- 1.9 MeV
      
        
      
      
        So, using Genfit track propagation with a Genfit final fit DOES
        produce a significantly better mass resolution than using our
        normal track seeding with a Genfit final fit. Also, adding a
        final fit with Genfit after Acts fitting produces an improvement
        in mass resolution of ~15%.
      
        
      
      
        The difference between 2) and 3) is interesting.
      
        
      
      
        Tony
      
      
        
      
      
      
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