PWG3: Femtoscopy project

Correlations and Fluctuations
1

http://triton.itep.ru/ions/NICA_FEMTO/2019/FEMTO_MPD_project.pdf

2

Hello.
Here are some comments on G.Nigmatkulov’s presentation from 21.11.2019.

  1. Outliers in reconstructed vertex transverse position:
    I ran 500 central events and could not reproduce this. Such a behaviour
    was seen quite some time ago (before March 2019) because of some cuts
    in vertex reco. So, I suspect that either the software for the production
    was not as mentioned (GIT commit f24601d9), or the MpdDst sample was
    produced earlier. In any case, it would be informative to look at the
    plot “Vertex.fY:MCEventHeader.fZ”

  2. Track parameters: TpcKalmanTrack contains track parameters at PCA
    to the point (X,Y)=(0,0). Therefore, to obtain track parameters at
    PCA to the reconstructed primary vertex, the PCA search using MpdHelix
    should be done.

  3. Tracks from the primary vertex fitted with a vertex constraint can
    be written to a container PrimTracks by using the switch in reco-macro
    ((MpdKfPrimaryVertexFinder*)findVtx)->SetConstrFlag(1);
    However, currently these tracks are not ported to MpdDst.

  4. By default, all particles from the generator are stored into MCTrack
    container. In addition, it also contains tracks from the GEANT transport
    if they produce a point in the detector (+ something else).

Best regards, Alexander

3

To confirm p.1 - I have looked at 30k central events from PHSD, produced by A.Mudrokh - no outliers in transverse vertex position are observed.
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