RE: question on beam position definition when rotations are involved.

Dear Mina,

the $start_transform .. $stop_transform cards transforms only the bodies that
they enclose, it doesn't affect the tracking, scoring, primary beam etc.
Therefore your primary beam is always wrt the primary axes system (x,y,z)
and not the (x,y',z'). If know you want to rotate also the beam you should
use the BEAMAXES cards in your input.

Regards
Vasilis

________________________________________
From: owner-fluka-discuss_at_mi.infn.it [owner-fluka-discuss_at_mi.infn.it] on behalf of Mina Nozar [nozarm_at_triumf.ca]=0A=
Sent: 18 May 2011 23:15
Cc: fluka-discuss_at_fluka.org
Subject: question on beam position definition when rotations are involved.

Hello,
I am working with a geometry with two sets of axes (x,y,z) and (x,y',z')
or rotation about x by some angle. A subset of the geometry, beam pipe
and target assembly are in the (x,y',z') coordinates and the rest
(shielding mainly) is in the x,y,z coordinates.
I do the rotation using ROT-DEFI and $start_transform, $stop_transform.
I start the beam inside the rotated coordinates (x,y',z'). I am
wondering what the and y coordinates of the beam refer to in this case?
Are x and y position of the beam with respect to the rotated
coordinate system? I set a 'cosy' to align the beam with the centerline
of the beam pipe and target assembly.
I am a new fluka user and hope my question above is clear. Is there a
way to visualise the beam when looking at the geometry? Is there a way
to check that the beam is in fact going through the center of the target?

Thanks and best wishes,
Mina
Received on Thu May 19 2011 - 11:03:46 CEST