From: Stefan Roesler (sroesler@mail.cern.ch)
Date: Wed May 16 2007 - 18:14:00 CEST
Dear Vincent,
There is no model available which could treat your interactions.
In principle, a model for nuclear interactions below 100MeV/nucleon will
be made available soon (BME model). However, it will not be able to treat
interactions of nuclei lighter than alpha. In principle, there are
alternative model solutions, such as "fusion" of the deuterium with the
target nucleus and application of PEANUT to the decay of the resulting
system but I am not aware if (and when) this will be implemented.
Greetings,
Stefan
On Wed, 16 May 2007, Feracci Vincent wrote:
> Dear Sebastien and Stefan,
>
> First thank you very much for answering my previous mail, however there are a
> still a few things which still seem a bit obscure to me: are there pertinent
> models for nuclear interaction below 100 MeV/nucleon available somewhere for
> FLUKA (i.e which would properly deal with the interaction of 40 MeV deutons
> with carbon for example) and if there are not, how did you Sebastien manage to
> have coherent results in your Fluka Spiral2 simulation?
> I have run my simulation without DPMJET nor PHYSICS: IONSPLIT and no nuclear
> interaction is taken into account.
> Thank you in advance and regards,
>
> Vincent Feracci
> Intern at the GANIL on SPIRAL2 project
> feracci@ganil.fr
>
> Stefan Roesler wrote:
>
> > Dear Vincent,
> >
> > In addition to what Sebastien wrote (i.e., there is no model for nuclear
> > interactions below 100MeV/nucleon in the distributed version) you are
> > using
> > PHYSICS 1.0 0.001
> > IONSPLIT
> >
> > which splits the deutron into its nucleons before being transported. This
> > way you always get at minimum one neutron, which is unphysical in this
> > case.
> >
> > Greetings
> > Stefan
> >
> > -----Original Message-----
> > From: owner-fluka-discuss@mi.infn.it on behalf of Sebastien WURTH
> > Sent: Tue 5/15/2007 5:28 PM
> > To: Feracci Vincent
> > Cc: fluka-discuss@fluka.org
> > Subject: Re: Problem with deuton converter
> >
> > Hello Vincent,
> >
> > Your beam energy is too low to get interactions through DPMJET (it is
> > transparent here). I did a SPIRAL2 simulation with FLUKA, and although it
> > wasn't the purpose of my study, I scored neutron fluence in the converter (a
> > cylinder of 7.7 cm radius and 1 cm thick) : 2.17e+14 n/cm²/s (with usrtrack
> > then) and coming out from converter (usrbdx over 4 pi) : 1.17e+14 n/cm²/s.
> > My beam was not cylindrical but rectangular 3cm*3cm, 40 MeV, 5 mA (ie
> > 3.125e+16 d/s).
> > I found that is was not so far of the given values for 2.83 and 4 cm beam
> > diameters respectively 1.1e+14 and 7e+13 n/cm²/s.
> > I read that the neutron yield should be ~2.5% per deuteron over 4pi.
> >
> > Regards.
> > Sébastien.
> >
> > Feracci Vincent a écrit :
> >
> >
> > > Hello Fluka users,
> > > I am simulating the bombardment of a cylindric graphite converter (8 cm
> > > diameter, 1 cm thick) by a 40 MeV deuton beam (gaussian spatial
> > > repartition) in order to produce neutrons. However in my simulation I
> > > measure a convertion factor which is close to 1 ( 1 deuton creates 1.1
> > > neutron) while it should be, according to other simulations and
> > > experiments about 0.01. In order to take into account deuton interaction,
> > > I used the following parameters:
> > > DEFAULTS
> > > PRECISIO
> > > EVENTYPE 2.0
> > > DPMJET (i have linked the DPMJET library)
> > > PHYSICS 1.0
> > > COALESCE
> > > PHYSICS 3.0
> > > EVAPORAT
> > > PHYSICS 1.0 0.001
> > > IONSPLIT
> > >
> > > LOW-NEUT 72.0 22.0 0.0196 1.0
> > > I used Usrtrack and Usrbdx to measure fluence inside the converter and at
> > > given angles of the incident deuton beam. I run my calculations on FLAIR
> > > V0.4 and simulated with 20.000.000 primaries separated in 50 runs.
> > > I am unsure of the physics models I have used but I can't manage to
> > > understand what is wrong with my simulation. I have attached my input file
> > > to this mail. Is it a problem of energy threshold for the deutons who by
> > > consequence all split to give neutrons?
> > > Thanks in advance,
> > >
> > > Vincent Feracci
> > > Intern at the GANIL on SPIRAL2 project
> > > feracci@ganil.fr
> > >
> >
> >
> >
> >
> >
> >
>
>
>
-- ___________________________________ Stefan Roesler CERN, SC/RP CH-1211 Geneva 23 Switzerland Phone: +41-22-7679891 Fax: +41-22-7669639 E-mail: Stefan.Roesler@cern.ch
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