Re: rotating event with brag

From: Flemming Videbaek (videbaek@sgs1.hirg.bnl.gov)
Date: Wed Dec 04 2002 - 12:23:04 EST

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    Hi Djamel
    
    If you look for nkine(1)==5 ie. zebra input there is I believe proper code
    for dealing
    with the keeping the phi's to check in range (-pi,pi) while the oscar input
    is written differently
    - by the way why the nkine==4 does not have the rotang - which I think it
    should is obscure.
    Not that the nkine(5) code handles both flowing over pi and going below -pi
    (if rotang was negative e.g)
    
    It is good if you consolidate code and commit.
    
    Flemming
    
    ------------------------------------------------------
    Flemming Videbaek
    Physics Department
    Brookhaven National Laboratory
    
    tlf: 631-344-4106
    fax 631-344-1334
    e-mail: videbaek@bnl.gov
    
    ----- Original Message -----
    From: "Djamel Ouerdane" <ouerdane@nbi.dk>
    To: "Brahms Devel List" <brahms-dev-l@bnl.gov>
    Sent: Wednesday, December 04, 2002 12:02 PM
    Subject: rotating event with brag
    
    
    > 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
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    >
    >
    


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