RE: source.f - how "transparent" ?

From: Helmut Vincke (
Date: Fri Jul 06 2007 - 17:06:59 CEST

  • Next message: Vasilis Vlachoudis: "RE: usdraw & mgdraw.f"

    Dear Thomas

    The parameters of beam and beampos are transferred to the code partly in
    case you use the SOURCE parameter.

    In detail: the position and the direction is taken into account (beam
    pos), however, the spatial distribution which is given by the parameters
    WHAT(4 - 6) are not considered in the simulation if SOURCE is used. I
    did already the mistake of expecting an extended source, using the
    source card and the BEAM What 4 - 6 together. Fortunately I checked it
    with a fluence detector and it turned out to be a pencil beam instead of
    a circular beam which I have expected.


    -----Original Message-----
    [] On Behalf Of Alberto Fasso'
    Sent: Freitag, 6. Juli 2007 14:13
    To: Thomas Otto
    Cc:; Jerome Desarzens
    Subject: Re: source.f - how "transparent" ?

    Hi Thomas,

    > I need to define a particle source with circular diameter, emitting an

    > particles according to an energy spectrum.
    > The manual is not 100% clear on this issue, is the following approach
    > correct:
    > - I define the gemetrical parameters of the source in what(4)and
    what(5) of
    > BEAM

    Actually, you need also what(6): otherwise, you get a beam with a
    section. To get a circular section, define it as annular with internal
    radius = 0.
    And probably you need also what(3) to request an isotropic source
    you get a parallel source along z: is that what you want?)

    > and in what(1) - what(3) of BEAMPOS (the particles will tracel in
    > positive z-direction)
    > - I sample the kinetic energy from my spectrum within source.f. The
    > geometrical parameters are left untouched by source.f and are passed
    on to
    > the code, which will generate a gemoetrically extendend source.
    > Thank you for confirming or correcting this assumtion,



    Alberto Fasso`
    SLAC-RP, MS 48, 2575 Sand Hill Road, Menlo Park CA 94025
    Phone: (1 650) 926 4762   Fax: (1 650) 926 3569

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