From: Sebastien WURTH (email@example.com)
Date: Tue May 15 2007 - 17:28:39 CEST
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:
> EVENTYPE 2.0
> DPMJET (i have linked the DPMJET library)
> PHYSICS 1.0
> PHYSICS 3.0
> PHYSICS 1.0 0.001
> 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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