Re: Score only the source neutron undergoing absorption and scattering ,excluding fission neutron.

From: Santana, Mario <msantana_at_SLAC.Stanford.EDU>
Date: Sun, 1 Apr 2012 22:45:07 -0700

Coming back to your question from several weeks ago, I understand you want
to score neutrons other than those coming from fission. I have looked around
the documentation and these are my conclusions:

1- I don't see that any flag is attached to the neutrons to discriminate
those that resulted from a fission process. Therefore I don't think that it
is possible to score neutrons that come from fission or neutrons that don't
come from fission. They are all scored together.

2- The other alternative would have been to switch off fission, but again,
I am not sure there is a knob from the user end to accomplish that.

3- As a result of 1 and 2, I don't see any way to achieve the scoring you
asked for other than maybe manipulating the source code. Of course you can
score fissions, low energy fissions and high energy fissions, but I don't
think that from that information you can get what I think you were asking


> Thanks for your advice.
> I followed your advice, but it didn't work.
> If I score BEAMPART 210 Primary (source or beam) particles, the result is
> fluence of Primary neutron, without any interaction such as absorption and
> scattering.
> This is NOT exactly what I want.
> Let me clarify my need.
> The source neutrons, undergoing absorption, scattering and fission, moveto
> the detector. I want to calculate the fluence of neutrons in the detector.
> But I want to exclude any fission neutrons in my fluence result.
> Thanks again.
> -----Original Message-----
> From:
> []
> Sent: 2012 17:17
> To: sugenghua;
> Subject: RE: Score only the primary neutron,excluding fission neutron.
> Try to use for scoring in your estimator this general particles:
> BEAMPART 210 Primary (source or beam) particles
> (See also Fluka Manual page 45)
> Cheers
> -----Original Message-----
> From:
> [] On Behalf Of sugenghua
> Sent: Montag, 20. Februar 2012 02:21
> To:
> Cc:
> Subject: Score only the primary neutron,excluding fission neutron.
> Dear FLUKA experts:

> Please help me with my problem. Thanks.
> In my model, the source particle is neutron, emiting from the fuel
> assembly in the middle. Water and iron surround the fuel assembly.
> I want to score the fluence of neutron in the iron.
> I want to score only the source neutron or called primary neutron,
> excluding fission neutron. Namely, I don't want secondary neutron to be
> transported and scored. Or, I want to switch off fission. What can I do
> with FLUKA?
> As I know, in MCNP, there is a NONU card, Fission Turnoff Card.
> This card turns off fission in a cell. The fission is then treated as simple
> capture.
> The following is my thoughts, which I have tried and got no effect.
> (1)If WHAT(6) of LOW-NEUT is 0.0,is fission neutron multiplicity
> forced to 0?
> (2)In user routines MDSTCK(management of the stack of
> secondaries),
> NUMSEC is number of secondary particles produced in the
> interaction, can I just NUMSEC=3D3D3D0?
Received on Mon Apr 02 2012 - 09:32:57 CEST

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