Re: Question: How to stop neutron transport below 1 MeV and beyond 20 MeV

From: Mohammad Islam <>
Date: Mon, 9 Apr 2012 15:30:58 -0500

Dear Fluka Experts,

Many many thanks to vasilis and andrea for pointing out the the error I
made. I can see it now. Actually I am fairly new to fluka and trying to
learn the acitivity of different CARDS and its associated physics.

Following the suggestion made by Mr. Vasilis, I tried to activate the
USERWEIGht card and incorporated the lines

          (IF ( ISCRNG .EQ. 1 ) THEN
          IF (J0TRCK .NE. 8 .OR. KTRACK.EQ.0 .OR. KTRACK.GT.102) COMSCW =
          END IF)

  in the code comscw.f and modified it to comscw_mod.f for the scoring from
1-20 MeV Neutrons. But I could not get it worked. I also followed chapter
13 in the manual. I could not get fortran code compiled (complier f77,
Fedora 15) in the first place. As I am not familiar with linux or fortran,
I am finding it really hard at this point. Please help me with an example
if possible.

I attached here my input and comscw_mod.f card for expert opinion.
Again please help me in solving my problem: Scoring dose equivalent in
different detectors (CR3901, CR3902.....CR3912)* only from neutrons of 1-20
MeV. *

Looking forward to answer.

PhD student, Oklahoma State University

On Thu, Apr 5, 2012 at 10:02 AM, Vasilis Vlachoudis <> wrote:

> Hi Mohammad,
> indeed as Andrea pointed out there is no point in stopping the transport
> above 20MeV,it would be physically wrong (killing neutrons that could
> potentially arrive to your detector with less than 20 MeV).
> You can stop the transport at 1 MeV BUT if you are sure that your detector
> is not efficient for lower energies and you don't have any material
> (e.g. fissionable) that could generate higher energy neutrons, or alpha
> particles.
> One possible way would be to activate with the USERWEIGht card the
> call to the COMSCW routine and modify the comscw.f routine accept the
> scoring if
> the energy of the particle was in the 1-20MeV limit.
> J0TRCK is the original particle 8=3DNEUTRON,
> KTRACK is the neutron group with 102~=1MeV (Look the manual Section 10.4).
> These lines says for the first USRBIN scoring ignore all particles other
> than neutrons
> or energy >20MeV (KTRACK.EQ.0)
> or energy <1MeV neutron group higher than 102
> Of course all the above hold with the assumption that your CR39 is not
> sensitive to other particles e.g. alphas
> Vasilis Vlachoudis

Received on Tue Apr 10 2012 - 09:43:15 CEST

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