Date: Sun, 9 Jul 2017 19:00:18 +0200
Hi Tom,
in addition to Vasilis suggestions (do not forget redefine AIR too,
maybe to AIR2,
to avoid conflicts wth the pre-defined AIR), have you tried to increase
the statistics
of your run? I have obtained the attached plot with 1e8 events.
Andrea
Il 09/07/2017 13:01, Tom Jonas Janzen ha scritto:
>
> Dear Vasilis,
>
> at least i can try. The detectors of my simulation are cylinders with
> a thickness of 1cm (10 cylinders). With the help of those cylinders i
> am able to track the neutron fluence inside of the cylinders depending
> on the energy of the neutrons and the travelled distance of the neutrons.
>
> All my simulation results for the materials PMMA, HDPE and Water (all
> moderator mterials) are almost identically. The neutron fluence hits
> the maximum at the energyspectrum of 2E-11 GeV, which is the energy
> level of neutrons. This means, that the moderation of neutrons is good
> with those materials and as the results the neutron fluence is rising
> in the energy spectrum of thermal neutrons.
>
> Only the results of graphite are different. The neutron fluence hits
> it‘s maximum at the starting energy of my neutron source (0,003 GeV)
> and then only decreases. No further maximums and especially no
> detectable neutron fluence inside the thermal energy spectrum. Also
> the plots of my _tab.lis files are normaly standardized in the range
> of 1E-12 to 1E-9 GeV on the x-axis. But in the case of graphit i had
> to decrease the range to
>
> 1E-8 to 1E-2 GeV due to the lack of detectable neutron fluence in
> lower energy ranges (e.g. 1E-11 GeV).
>
> So i expected from the simulation with graphite results, which are
> comparable to the results of PMMA, HDPE and Water. I hoped to see a
> increase of the neutron fluence on the energy level of 1E-11 GeV.
> Therefore i questioned myself, if graphite only moderates fast
> neutrons? Is there another cross section for graphite, which allows me
> to simulate neutron fluence in lower energy ranges, especially at
> 1E-11 GeV (thermal level)? Why is there no detectable neutron fluence
> in the energy spectrum of 1E-12 to 1E-9 GeV?
>
> I hope i could explain my problem a bit better for you!
>
> Again thank you for your time effort!
>
> Cheers,
>
> Tom
>
-- ======================================================================== Dr. Andrea Fontana tel: +39 0382 987991 Istituto Nazionale fax: +39 0382 423241 di Fisica Nucleare Sezione di Pavia e-mail: andrea.fontana_at_pv.infn.it Via Bassi 6 web : www.pv.infn.it/~fontana 27100 PAVIA, Italy ========================================================================
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(image/png attachment: graphite_1e8ev.png)