RE: p+U reaction

Dear Andrzej and Lucia,

the main reason for the difference between neutrons produced and neutrons
exiting from the target is that not all produced neutrons can escape,
but some interact inside the target, getting absorbed.

Alberto

________________________________________
From: owner-fluka-discuss_at_mi.infn.it [owner-fluka-discuss_at_mi.infn.it] On Be=
half Of Lucia Sarchiapone [Lucia.Sarchiapone_at_lnl.infn.it]
Sent: Tuesday, July 20, 2010 4:15 AM
To: Andrzej Wojciechowski
Cc: fluka-discuss_at_fluka.org
Subject: Re: p+U reaction

The main difference is due to the fact that the fluence is a quantity
that takes into account the direction of the particle with respect to
the boundary between the regions. In the manual you can read that the
fluence is weighted with the inverse of the cosine of the angle between
particle direction and normal to the surface.
In principle you can get rid of this weighting factor scoring current
instead of fluence, but you will still find some difference because -I
guess, and I hope that someone corrects me if I'm wrong - with the
USRBDX you are scoring neutrons from all interactions, not just the
inelastic ones.

Lucia

On Jul 19, 2010 02:39 PM, Andrzej Wojciechowski<andrzej_at_cyf.gov.pl>
wrote:

> Dear Lucia
> Do you explain me why the total fluence of neutrons scored with the
> USRBDX estimator, crossing the boundary between region R3 and R4
> is diferent than the "Number of secondaries generated in inelastic
> interaction per beam particle" for neutron?
> Kind regard
> Andrzej
>
> Dnia 15-07-2010, czw o godzinie 14:41 +0200, Lucia Sarchiapone pisze:
> > Dear Andrzej,
> >
> > you are probably looking at the total fluence of neutrons scored
> > with
> > the USRBDX estimator, crossing the boundary between region R3 and
> > R4.
> > In my opinion if you want to look for the number of neutrons
> > generated
> > per primary proton you should look at the standard output file
> > (*.out).
> > In the list called "Number of secondaries generated in inelastic
> > interaction per beam particle" you will find that neutrons are
> > something
> > like 37.8 (depending on the number of primaries you run in the
> > simulation). This value is much closer to the experimental one.
> > Cheers,
> >
> > Lucia
> >
> >
> > On Jul 14, 2010 04:27 PM, Andrzej Wojciechowski<andrzej_at_cyf.gov.pl>
> > wrote:
> >
> > > Dear FLUKA users
> > > I am traying calculate the total number of neutron produced during
> > > reaction p+U-238 (see attachment) (1.22GeV)
> > > The experimental result[1] equal to 38.8+-5%,
> > > the calculation result egual to 44.0
> > > What am I doing badly?
> > >
> > > Kind regards
> > > Andrzej
> > >
> > > [1] L. Pienkowski,* F. Goldenbaum, D. Hilscher,=3DC3=3DA2? and U.
> > > Jahnke,
> > > Neutron
> > > multiplicity distributions for 1.94 to 5 GeV/c proton-,
> > > antiproton-,
> > > pion-, kaon-,and deuteron-induced spallation reactions on thin and
> > > thick
> > > targets.PHYSICAL REVIEW C VOLUME 56, NUMBER 4 OCTOBER 1997
>=
Received on Tue Jul 20 2010 - 20:38:28 CEST