Re: rotating event with brag

From: Flemming Videbaek (videbaek@sgs1.hirg.bnl.gov)
Date: Wed Dec 04 2002 - 21:09:39 EST

  • Next message: Christian Holm Christensen: "OSCAR reading (was Re: rotating event with brag)" 
    Well,
not quite; the brajms geant itself only cares about px,py, and pz which are
done correctly modulo 2pi.
The issues at hand in brag is only the p,phis and theta selection.

    Flemming

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

tlf: 631-344-4106
fax 631-344-1334
e-mail: videbaek@bnl.gov

----- Original Message -----
From: <murray@comp.tamu.edu>
To: <brahms-dev-l@bnl.gov>
Sent: Wednesday, December 04, 2002 4:59 PM
Subject: Re: rotating event with brag


>    Dear Djamel,
>            this reminds me of similar issues with GEANT at the cyclotron.
I think
> you are right that angles have to lie withing -180 to 180.
>              Yours Michael
>
> Quoting Djamel Ouerdane <ouerdane@nbi.dk>:
>
> > Hi all,
> >
> > Marco and I've just had quite a struggle with brag. He had a bug that
> > looked odd at first glance. He sent hijing events through brag and
applied
> > some rotations in phi. The result was : as the rotation angle grew above
a
> > certain limit, output files were smaller and smaller in size. The last
> > rotations had no useful data in it.
> >
> > So, I suspected it had to do with the rotang treatment. I dug into
> > brag/src/user/guxint.F in the part dealing with oscar input.
> > I realized by making several tests that when the phi angle of a
particle,
> > after a rotation was applied, ended up > 180 deg., brag would ignore it.
> > This was especially true with Marco's phi range (-30 to 30 deg. only).
> >
> > The fix was to remove 360 deg. to particles with phi angles > 180 (so
that
> > they end up to the negative half of the full phi range).
> >
> > But I haven't committed anything. I ask the experts to make sure this is
> > the right thing to do and if such fix should be applied to other nkine
> > sections.
> >
> > Djam
> >
> >
> > --
> > Djamel Ouerdane ------------------------------------------o
> > |  Niels Bohr Institute      |  Home:                     |
> > |  Blegdamsvej 17, DK-2100 Ø |  Jagtvej 141 2D,           |
> > |  Fax: +45 35 32 50 16      |  DK-2200 Copenhagen N      |
> > |  Tel: +45 35 32 52 69      |  +45 35 86 19 74           |
> > |                  http://www.nbi.dk/~ouerdane            |
> > |                  ouerdane@nbi.dk                        |
> > o---------------------------------------------------------o
> >
> >
>
>
>
>
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