Re: Rotation of local tracks

From: Flemming Videbaek (videbaek@sgs1.hirg.bnl.gov)
Date: Wed Apr 10 2002 - 11:40:02 EDT

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    Hi Claus,
    
    Yes I have a comment - until we understand why the rotation help
    - and demonstarted it is really a rotation this should ONLY be used for
    checking out analysis NOT used in any production!
    
    Flemming
    
    PS on the cleanup of tracks - I agree this was not done previous
    - one reason is that you can envision scenario's in which , what I guess
    you have done cleaning up first back and then front leads to ambiguities
    not that it will do it most cases - I will revies when I come back.
    I also agree it should be done. Good.
    
    Flemming
    
    
    
    ------------------------------------------------------------------
    
    Flemming Videbaek 
    Physics department, Brookhaven national laboratory
    Upton L.I., NY11973, USA
    
    Phone: (516)-344-4106 
    FAX:   (516)-344-1334
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    e-mail: videbaek@bnl.gov
    
    
    
    On Wed, 10 Apr 2002, Claus O. E. Jorgensen wrote:
    
    > 
    > I forgot to communicate one change I did in the BrModuleMatchTrack.
    > 
    > It has been observed that the momentum dependence of the Dang matching
    > parameter can be avoided by a small rotation og the local tracks. I've
    > added a method to the BrModuleMatchTrack where this rotation can be set:
    > 
    > SetRotationFactors(fFrontRot, fBackRot)
    > 
    > In the code the angles are changed like this:
    > ...
    > tpcAngleBack.SetX(BackTrack_p->GetAlpha()[0]*fBackRot);
    > ...
    > tpcAngleFront.SetX(FrontTrack_p->GetAlpha()[0]*fFrontRot);
    > ...
    > 
    > By default the rotation is 1, so if you don't use this method you'll not
    > notice the change. But for example by setting 
    > SetRotationFactors(1.01,1.01) in the ffs matching the dang vs p will be
    > much better. Ian and Flemming probably have some comments on this...
    > 
    > Claus
    > 
    > +-------------------------------------------------------------+
    > | Claus Jørgensen                                             |
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    > +-------------------------------------------------------------+
    > 
    



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