Re: user routine SOURCE

From: Mary Chin <>
Date: Fri, 8 Jul 2011 15:57:19 +0200

Hai Bob,

In the presence of the SOURCE card, setting WHAT(3) of the BEAM card to
>2000*pi no longer gives us an isotropic source. The isotropic
distribution must then be requested from source.f. There are different
ways of doing this; one is to insert the line
before the assignment of the cosines. Ref.
page 21.

As for the maximum allowable value of START's WHAT(1), I was tempted to
say, "more than we ever need!" but then I thought you might not accept
this as a valid answer. So here I give an empirical finding: on my desktop
I tried 1e18, no problem. But when I tried with 1e19, I got a core dump
before the first history had any chance to start.

:) mary

On Thu, 7 Jul 2011, wrote:

> Hello all
> In the end of " Sampling from a biased distribution",it says:
> Important!
> The values of beam characteristics defined by commands BEAM (p. 64) and
> POLARIZAti (p. 182) are available in COMMON BEAMCM: the angular
> divergence (variable DIVBM), beam width (XSPOT and YSPOT), and the
> polarisation vector (UBMPOL, VBMPOL, WBMPOL) can help to set up a scheme
> to sample the corresponding quantities from user-defined distributions.
> But sampling from the distributions pre-defined by BEAM and POLARIZAti
> is not simply inherited by subroutine SOURCE: it is the responsibility
> of the user to write such a scheme!
> I have to activated SOURCE with my source routine,because the particles
> of my sample are not monoenergy.At same time,i need an isotropic
> distribution in particle direction.So how should i do?
> 1 Assigning a value(>2000*pi) to variable DIVBM ,which can be overridden
> in user routine SOURCE?
> Or
> 2 Write myself a scheme for the isotropic distribution in user routine
> One more question,in START card WHAT(1)=3Dmaximum number of primary
> histories simulated in the run
> Default = 5000.0
> what is the maximum value of the WHAT(1) in START?
> forgive me for my ignorance and best regards!
> Bob
Received on Fri Jul 08 2011 - 16:38:12 CEST

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