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Re: URGENT: geane - coordinate system [message #5116 is a reply to message #5113] Fri, 28 September 2007 14:17 Go to previous messageGo to previous message
Sebastian Neubert is currently offline  Sebastian Neubert
Messages: 282
Registered: March 2006
Location: Munich
first-grade participant

From: *e18.physik.tu-muenchen.de
Hi!

I have look into CbmTrackParP and I found the place where the confusion sets in:

TVector3 positionsd = util.FromMARSToSDCoord(TVector3(fX, fY, fZ), forigin, fiver, fjver, fkver);
   fU = positionsd.X(); // CHECK
   fV = positionsd.Y(); // CHECK 
   fW = positionsd.Z(); // CHECK 


Since fV and fW are used in the trackrepresentation it is implicetely assumed, that X is along the track. So it has indeed nothing to do with the beam-axis.

In other words:

I would like to have: pos=(1,1,0) mom=(0.1,0,1) in MARS

when being projected onto a plane
o(0,0,0) u(1,0,0) v(0,1,0)

to give
v=1; w=1; v'=0.1; w'=0;

this is currently not the case because of the code shown above.
instead one would get
u=1; v=1; u'=0.1; v'=0;


In principle we should use fU and fV or build in some conversion somewhere.
Still thinking about it....

Cheers! Sebastian.


Sebastian Neubert
Technische Universität München
Department Physik E18
sneubert@e18.physik.tu-muenchen.de
tel: +49-8928912592
 
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