RE: question about isotropic source

From: Anton Lechner <Anton.Lechner_at_cern.ch>
Date: Thu, 28 Jun 2012 10:49:01 +0000

Dear Zijia,
In fact, you can use the BEAM and BEAMPOS cards to create the source you describe in your Email:

1) Isotropic distribution:
You can get an isotropic distribution by setting the WHAT(3) of the BEAM
card to a value larger than 2000*pi*mrad.

2) Spatial distribution of source particles:
As a second step, you can define the cylindrical distribution of source
particles using the BEAMPOS card (and potentially the BEAMAXES card if the
cylinder axis is not parallel to the z-axis of the geometry reference system):
For example, to set up a cylindric source distribution
-) with radius=3D1cm and height=2cm,
-) centered at x=5cm, y=5cm and z=5cm,
-) and where the cylinder axis is parallel to the z-axis
use the following two cards:
BEAMPOS 5.0 5.0 5.0
BEAMPOS 0.0 1.0 0.0 2.0 CYLI-VOL

If your cylinder is not parallel to the z-axis, you also need to change the
beam reference frame using the BEAMAXES card. In that case, the cylinder will
be parallel to the z-axis of the beam reference frame, which can be rotated
with respect to the geometry reference system.

Best regards,
Anton
Received on Sat Jun 30 2012 - 12:17:09 CEST

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