Fwd: Stopping Neutron in a defined region

Dear FLUKA experts,

Thanks Dr. Stefan for your suggestion.

My aim is to calculate internal neutron dose equivalent produced in the
phantom.. I want to stop the neutrons produced in the snout.

First of all, I looked at the discussion site for some help on source
  code. I tried to combine two previously discussed user routine from
discussion site for my purpose as I have no previous experience on fortran.
What I did is the following.

1. In step one, I set the phantom as BLCKHOLE as suggested and made a
region (upstream) in front of snout. After that, I generated an external
file for all the particles entering phantom from this upstream region using
*fluscw_step1.f. *I dont know if it is a correct approach to set an extra
region (here upstream) from where the particles entered the phantom. *

*2. In step two, I tried to read the file generated in step one using the
code *source_step2.f ( *the code is activated by SOURCE card in the input)
but I had no luck. Flair finish with errors. Could you please help me where
I did wrong at this step.

3. The next problem : suppose I can read the external file, but the file
carries all different sorts of particles where I don't want the neutron to
transport further. I can remove neutrons (particle code 8) from the
external file using some software and can use it. At this point, do I need
to further specify the position or direction in the source code as TXX,
TYY, TZZ and XX, YY, ZZ should contain these info in the external file. In
this step, if I can read the external file, I would just remove the snout
and set phantom to water. Do you think its okay?

I attached all my files used for step 1 and step 2. Did not attach the
generated dat file in step one as it is larger in size. Please help me to
correct my problems at Step 2 and 3. I am a new user and you may notice
lots of issues in the codes.

Thanks
Mohammad Rafiqul Islam
PhD Student, Oklahoma State University
USA

un, Jun 10, 2012 at 3:23 AM, Stefan Roesler <sroesler_at_mail.cern.ch> wrote:

> Dear Mohammad
>
> I think the cleanest way is performing the simulation in two steps:
>
> 1) set the phantom to BLCKHOLE and write into an external file all
> particles entering the phantom, e.g., via fluscw.f that is called at each
> boundary crossing, provided you define a (dummy) USRBDX for the boundary
> of interest and
>
> 2) write a source routine that reads in the particles from the first step
> and transports them further in the original geometry. This way you can
> start the cascades in the second step with whatever particles you like.
>
> Cheers
> Stefan
>
>
> On Fri, 8 Jun 2012, Mohammad Islam wrote:
>
> > Dear FLUKA experts,
> >
> > Thanks for being so much helpful.
> > I wanted to add few things in my previous email.
> >
> > I am calculating dose equivalent from neutrons produced in the snout and
> in the phantom. In order
> > to calculate the dose equivalent from internal neutrons (neutrons
> produced inside the phantom), I
> > need to dump the neutrons which are produced in the snout so that they
> can not reach the phantom.
> > How can I do that?
> >
> > Is it possible to place a thin region of low dense material in front of
> the snout where all the
> > neutrons produced in the upstream will be stopped (like a Bremsstrahlung
> electron problem
> > described fluka website FAQ). I have absolutely no idea what card to use
> and how to do that.
> > Please help me with any suggestions .
> >
> > Attached is my input and user routine used for Dose equivalent.
> >
> > Sincerely
> > Mohammad Rafiqul Islam
> > PhD student Oklahoma state University
> > USA
> >
> >
>
>
>