Re: [fluka-discuss]: calculate neutron yield_spallation

From: Alfredo Ferrari <alfredo.ferrari_at_cern.ch>
Date: Thu, 16 Jul 2015 08:29:33 +0200

Hi

actually tracklength distributed USRBIN with NEUTRON accounts also for
neutrons below 20 MeV and Vittorio is true that this is a fluence
estimator. USRBIN not tracklength distributed with NEUTRON counts
interactions (not neutrons) generated by neutrons above 20 MeV.

However I would like to point out that "neutron production" as already
explained in depth on this list in the past is physically meaningless,
ill-defined, and in the end subjective to the way things are scored.

The only meaningful (ans measurable) quantity is neutron escaping from a
given target with a given geometry with a given incident beam/energy.

All rest is crap Monte Carlo numerology

                    Alfredo


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| Alfredo Ferrari || Tel.: +41.22.76.76119 |
| CERN-EN/STI || Fax.: +41.22.76.69474 |
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On Wed, 15 Jul 2015, Vittorio Boccone wrote:

> Dear Eleni,
>  you seem to to use and USRBIN scoring NEUTRON (or better NEUTRON fluence).
>
> First NEUTRON generalized particle type will not give directly the quantity
> as it does not include neutrons generated below 20 MeV, i.e. (n,2n) or
> (n,3n) reactions, second the USRBIN is not really doing that type of job. An
> option - without writing and linking your routine - is to use the NEU-BALA
> which gives you the sum of all neutrons.
>
> The problem is that you must use the same type of estimator/scoring quantity
> and technique in both codes. And this is not always straightforward.
>
> V.
>
> On Wed, Jul 15, 2015 at 11:03 AM, Eleni Adamidi <eleni.adamidi_at_cern.ch>
> wrote:
> Hello,
>
> I am interested in calculating how many neutrons are generated
> in inelastic interactions per beam particle when a proton beam
> of 960 MeV hits a Pb target of 61cm diameter and 10,2height.
>
> The result I get is :
> 1.0596E+01 (63.9%)   0.0000E+00 ( 0.0%) NEUTRON
> so the neutron yield is 10.596, but compared with the same
> simulation in MCNPX (neutron yield = 17.910) there is a big
> deviation.
>
> I am attaching my input file in case you could check if there is
> something wrong.
>
> Thank you very much in advance,
> Eleni Adamidi
>
>
>
>

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Received on Thu Jul 16 2015 - 10:05:58 CEST

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