Hello Aaron & BlastTalk people,
First off, since BlastTalk is working and an archive is being
setup - please make the Subject line more descriptive, ie.
"a GEANT Vertex question"
question 1)
The key line in the fort.* file to make an extended target
is the line starting with "VERT". For example,
VERT 2 -1. -1. -20.0 2. 4. 40.0
|
|-- this is a vertex described with format "2"
in format two is a cube of uniform distribution.
the cube goes from (x,y,z) to (x+dx, y+dy, z+dz)
the format is:
VERT 2 x y z dx dy dz
so - in this example,
-1 < x < 1
-1 < y < 3
-20 < z < 20
two other formats are;
VERT 0
From Kevin. As described in "blast_proc.f"
C The NEW vertex default is distributed with a triangular
C z distribution 40.0cm long and a flat distribution in
C r and theta out to 0.5mm (1.0mm in diameter for the
C beam X target profile).
C
C This uses the rejection method to accept or reject
C events based on the probability distribution called
C funcz = triangle_dist(z) = -(1/20)*abs(z) + 1
there is also:
VERT 4 rho halfZ centerX centerY centerZ
These are described at the beginning of the subroutine "KIVERT"
in "blast_proc.f" with these words,
C. ******************************************************************
C. * *
C. * SUBROUTINE KIVERT *
C. * *
C. * Generates vertex coordinates according the data card VERT. *
C. * The first parameter (IFFVER) gives the type of vertex *
C. * distribution: *
C. * IFFVER = 1: Normal distribution with the following *
C. * parameters center (FFVER(1...3) and sigma *
C. * (FFVER(4...6) in the cartesian coordinates. *
C. * *
C. * IFFVER = 2: Constant distribution between lower limit *
C. * (FFVER(1...3) and upper limit (FFVER(1...3) *
C. * in the cartesian coordinates. *
C. * *
C. * IFFVER = 3: Constant distribution within tube of radius *
C. * FFVERT(1), of half-length FFVERT(2) in z *
C. * direction , and centered at FFVERT(3,4,5) *
C. * in Cartesian coordinates. *
C. * The NBUF user parameters UBUF are passed to GSVERT. *
C. * *
C. * ==>Called by : KIxxxx (event generator) *
C. * Author M.Guckes ******* (Oct. 1987) *
C. * modified: M.Guckes July 1986 *
C. * *
C. ******************************************************************
I find VERT 1 (normal distribution) dosn't work.
I think these should work with "KINE 5" - try it out.
But "KINE 5" has no place for vertex.
question 2)
> VERTEX #x #y #z #n
> ^
> |
> |
> number of prongs????
>
This is the number of vertex - but it is always equal to 1.
Tim Smith
On Mon, 27 Aug 2001, Aaron Joseph Maschinot wrote:
>
> Hello:
>
> I have a couple of GEANT questions, for anyone who might happen to know.
>
> 1) I am trying to use GEANT to produce "white"ly generated electrons.
> However, I need the electrons to be generated randomly anywhere within
> the target (specifically, I need to allow the electrons to be
> generated with the cylindrical target at rho values NOT equal to
> zero.) I have been loading the fort.38 file, as it deals with
> extended targets (the fort.48 file just crashes GEANT?????). However,
> when I view the results in the event.ascii file, the vertices of ALL
> the generated particles all occur at the same place: x = y = z =
> 0.000010. My question, then, is: is there a fort file that randomizes
> the vertice positions OFF the z-axis? Am I not doing something that I
> need to be doing? Or, perhaps, does the "extended source" description
> in the fort.38 file just refer to extension along the z-axis but not
> along rho? If so, any suggestions on how to include nonzero rho
> generation vertices? I would just use the KINE 5 generator with an
> external data file, except that the format in which the data in the
> external file needs to be entered has no place for the vertex data
> (i.e. the external file, a.k.a. fort.85, must have the format of:
>
> n
> id_1 p_1 theta_1 phi_1
> id_2 p_2 theta_2 phi_2
> ...
>
> It does not not accept vertex data.
>
>
> 2) What is a "prong", as listed in the event.ascii file, as the last
> paramter on the VERTEX line?
>
> VERTEX #x #y #z #n
> ^
> |
> |
> number of prongs????
>
> Thank you,
>
> Aaron
>
-- ____________________________________________________________________ Timothy Paul Smith Research Scientist MIT Bates Lab tim_smith@mit.edu 21 Manning Rd. tel: (617) 253-9207 Middleton, MA 01949 fax: (617) 253-9599
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