[Halld-offline] [EXTERNAL] request for help from tracking group

Naomi Jarvis nsj at cmu.edu
Wed May 6 09:57:50 EDT 2020


I think there might be something wrong with the FOMs from the
timebased tracks but I'm not really sure what I should expect.   The plots
below are for timebased tracks in the CDC with no reaction specified.  The
code snippet is below.  It's from the plugin CDC_TimeToDistance, maybe
there's a mistake in here.

I have been looking at track DOCA with time and found that selecting larger
FOMs made very little difference to this, although so far I only looked at
values from 1e-8 to 0.1. I have a few jobs with minimum FOM between 0.1 and
1 still running.

   vector <const DChargedTrack *> chargedTrackVector;


   for (unsigned int iTrack = 0; iTrack < chargedTrackVector.size();

      const DChargedTrackHypothesis* bestHypothesis =

      // Cut very loosely on the track quality

      auto thisTimeBasedTrack = bestHypothesis->Get_TrackTimeBased();

      if(!thisTimeBasedTrack->IsSmoothed) continue;

      if (thisTimeBasedTrack->FOM < MIN_FOM) continue;  // was 1e-10


[image: resid_vs_fom.png]
[image: resid_vs_fom.png]

On Wed, May 6, 2020 at 7:39 AM Richard Jones <richard.t.jones at uconn.edu>

> Hello all,
> I have been looking into differences between geant4 and geant3 simulations
> of k+ tracks at backward angles in the cdc, and have discovered what
> appears to be a sudden failure of the tracking past about 120 degrees in
> the cdc. Please see the final plot and comments here.
> https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_JeffersonLab_HDGeant4_issues_137-23&d=DwIFaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=Te_hCR4EUlJ6iCDYLJ8Viv2aDOR7D9ZZMoBAvf2H0M4&m=1fLa1BmvAoQHsEBCTMvR3oyNyTi849PjhfhNTTPDuLs&s=_Ppi0qVl3zAuzr-srtBkR2sQPz20dbKoPEob5m3cF90&e= 
> <https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_JeffersonLab_HDGeant4_issues_137-23&d=DwMFaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=Te_hCR4EUlJ6iCDYLJ8Viv2aDOR7D9ZZMoBAvf2H0M4&m=nHXw_4MCbSbzhcXPApg4pe8vH25eBETYPBlvns7oYvc&s=hLAiYzGqBJ5IdrEeCh6QrJksU3v12FUHm44NA63CNEc&e=>
> From hdview, I see that the number of hits on the track is very good up
> through DTrackTimeBased, and visually things look quite clean but the FOM
> values are terrible and there are no combos being generated. I am not sure,
> but don't combos need to be generated for these tracks to go further down
> the reconstruction chain? A set of 100 such tracks is available at:
> https://urldefense.proofpoint.com/v2/url?u=https-3A__zeus.phys.uconn.edu_halld_kstudy-2D4-2D2020_kstudysim-5Fsmeared.hddm&d=DwIFaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=Te_hCR4EUlJ6iCDYLJ8Viv2aDOR7D9ZZMoBAvf2H0M4&m=1fLa1BmvAoQHsEBCTMvR3oyNyTi849PjhfhNTTPDuLs&s=jqunK3BZlmtQSANEQAbcGTiWLzKt5lqEuWiJxmmaCfk&e= 
> <https://urldefense.proofpoint.com/v2/url?u=https-3A__zeus.phys.uconn.edu_halld_kstudy-2D4-2D2020_kstudysim-5Fsmeared.hddm&d=DwMFaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=Te_hCR4EUlJ6iCDYLJ8Viv2aDOR7D9ZZMoBAvf2H0M4&m=nHXw_4MCbSbzhcXPApg4pe8vH25eBETYPBlvns7oYvc&s=_XamR5Vx21DbQ5ZVCPiOB7ruQRpqTn3LhQJB_rO3Loo&e=>
> -Richard Jones
> _______________________________________________
> Halld-offline mailing list
> Halld-offline at jlab.org
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