From: Sebastien WURTH (firstname.lastname@example.org)
Date: Wed May 16 2007 - 16:56:29 CEST
Hello Vincent, Stefan, all,
I did have the same problem, deutons were transported but no interaction
took place and that's why after several trials, like you, I used PHYSICS
with SDUM=IONSPLIT, with what(2)=0.01 (and not 0.001 if this is of some
importance here). It is the only way I found to get interactions. My
first purpose was to estimate the activation of the cooling water from
UC2 target and the associated ion source.
Feracci Vincent a écrit :
> 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
> 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
>> PHYSICS 1.0 0.001
>> which splits the deutron into its nucleons before being transported.
>> way you always get at minimum one neutron, which is unphysical in this
>> -----Original Message-----
>> From: email@example.com on behalf of Sebastien WURTH
>> Sent: Tue 5/15/2007 5:28 PM
>> To: Feracci Vincent
>> Cc: firstname.lastname@example.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.
>> 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:
>>> 2.0 DPMJET (i have linked the DPMJET
>>> 1.0 COALESCE
>>> 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
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