From: Anna Ferrari <anna.ferrari_at_lnf.infn.it>

Date: Sun, 16 Jan 2011 19:23:47 +0100 (CET)

Date: Sun, 16 Jan 2011 19:23:47 +0100 (CET)

Dear Hamideh,

if I have well understood your needs, it seems to me that you want a

circular source in x-y plane, centered in (0,0,0) and with a certain

radius r, with the particles emitted I guess along z? Is it correct?

Said that, I don't understand why you want to use UBEAM, the tx direction

cosine, to define the radius of your distribution. This is in any case not

correct, the radius r must be defined inside the source.

Moreover, IF I understood correctly your source, I would not touch the

polarization cosines (because tx=0, ty=0 and tz=1 are already the right

choice).

Last: if you want a uniform distribution of the source coordinates in the

circle, take care about the sampling... if you uniformely sample the

radius r between 0 and 1 you get a not uniform particle density, having

more particles originating close to the center.

Hope it helps,

kind regards

Anna

*> Dear FLUKA experts
*

*>
*

*> I'm going to define a circular beam in x-y plane ( a beam which
*

*> travels around a circle of radius r and center (0,0,0)). Is it correct
*

*> if I follow these steps:
*

*>
*

*> In BEAMPOS card:
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*> WHAT(1)-WHAT(3):x,y,z coordinates of the center of the
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*> circle(XBEAM-YBEAM-ZBEAM)
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*> WHAT(4): radius of the circle (UBEAM)
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*>
*

*> Then I modify source.f by adding these command:
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*>
*

*> r = UBEAM * (FLRNDM(dummy)
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*> alpha = 2 * PI* (FLRNDM(dummy))
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*>
*

*>
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*> XFLK (NPFLKA) = XBEAM + r * COS(alpha)
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*> YFLK (NPFLKA) = YBEAM + r * SIN(alpha)
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*> ZFLK (NPFLKA) = ZBEAM
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*>
*

*> I would be grateful for your help.
*

*> Hamideh
*

*>
*

*>
*

Received on Sun Jan 16 2011 - 19:56:39 CET

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