[Brahms-dev-l] Re: Projecting FS tracks

Dear Catalin,

I have updated the BrFsGlobalFitting Module so it will restore the old
behaviour - I agree with the statements
given below by Kris, so think about the modification as a temporary fix that
can move us along towards QM on a rapid timescale. Specifically the dst will
have to be redone, added the refitting as the first step in the module
chaing.
I assume this will work but have not tested this. All the information needed
should be present in the gts' and fstracks.
Could you please check this and let me know ASAP.

Flemming

For those of you who wants to use the fitting module with pp , dA and/or
even low energy cucu data the method to get  the projected vertex is by  '
fit->SetTrackBeamVtx(kTRUE) for the global fitting module. This has been
done for
the run05 globalTracking.C script.

Brat is updated and version bumped.(as well as bdst)

Crs queues have been reopened.



message from Kris
--------------------

Hello,
The tracks from the global fitting routine are the track swam backwards
through D1 and projected to x=0.  That seems a logical place to project
to because we wish to know whether this track is associated with
whatever vertex measurement so that if it comes from downstream/upstream
that it could be eliminated.  Once one decides that this track, in fact,
originates from the vertex, one might use the better vertex information
to improve the track.  I have envisioned that to be in another module
which might be very closely associated with the global track fitting
routine but this time also including the vertex as a fitting point.  Any
track that comes out of that routine should be "consistent" with the
vertex.  As all of my analysis so far has been with the INEL, that has
not been an issue because between a FS track projection and the INEL
vertex, they are both bad, so I just used the track projected vertex as
the path of least resistance.

So I think the tracks coming out of the global fitting routine should
contain the track projected vertex and not modified.

Kris

----------------------------------------------------------------
Flemming Videbaek
Physics Department
Brookhaven National Laboratory

e-mail: videbaek@bnl.gov
phone: 631-344-4106
----- Original Message ----- 
From: "Catalin Ristea" <ristea@nbi.dk>
To: "Flemming Videbaek" <videbaek@bnl.gov>
Cc: "Ian Bearden" <bearden@nbi.dk>
Sent: Friday, June 17, 2005 10:28 AM
Subject: Projecting FS tracks


>
>    Dear Flemming,
>
>    There is this problem with projecting the fs tracks to the BB
> vertex, in order to make the elliptical cut on vertex difference.
>    I've tracked down where this is coming  from.
>    The problem is in BrFsGlobalTrackFitModule, where the track is
> intersected with the beam plane, and not with the plane perpendicular
> to the beam line in the BB vertex - like for the ffs tracks in the
> gtr files. This is why the x distance is always 0 for all the fs
> tracks...
>    What do you think we should do next?
>
> Kind regards,
> Catalin.
>
> -- 
> Catalin Ristea---------------------------------
> High Energy and Heavy Ions Group
> Niels Bohr Institute
> Blegdamsvej 17, 2100 Copenhagen, Denmark
> Tel (+45) 35 32 54 04 / Fax (+45) 35 32 50 16
>
> E-mail: catalin.ristea@nbi.dk
> http  : www.nbi.dk/~ristea
> -----------------------------------------------
>


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