From: Ludwik Pienkowski (firstname.lastname@example.org)
Date: Wed Oct 22 2003 - 18:12:32 CEST
Dear FLUKA authors,
Thanks to Alfredo for the explanation concerning the strange cases
that show single neutron interactions at low energy. If I well
understand this explanation, all spectra from the neutron transport
at low energies are expected to show unphysical shape, and only
the average values of the variables are to be considered meaningful.
Please look at the following test in which neutrons of two close
energies 19.5 MeV and 19.7 MeV hit a virtually infinitely thick
lead target. The program (attached to this email) counts the total
energy deposition using the routine mgdraw. The energy deposition
spectra are shown in file n2test.pdf. It is observed that only
average energy depositions are similar for both energies
(19.5MeV and 19.7MeV), while all other observables differ wildly.
1.RMS=22.7 and 9.9 MeV, for the two energies, respectively
2.a very strange shape at 19.5 MeV and a nice gaussian shape
at 19.7 MeV
Moreover both spectra show a long tail. There are many events
that show energy deposition much larger than the available energy.
This test run is closely related to my main task for which I'm
trying to use FLUKA. The task is to estimate the neutron detection
probability inside a detector, for example inside a solid crystal
cube of a volume of about 1dcm3. This probability I'm trying to
estimate from the energy deposition spectra looking for the events
that deposit energy inside the crystal above a given threshold.
However, the observations from the presented test run show me that
I'm not sure that I can use FLUKA for this purpose.
Would you have any suggestions for me on whether and how could
I use FLUKA to treat the above problem.
P.S.The attached files input files:
and energy deposinon spectra figure:
lfluka -o n2test -m fluka mgdraw-n2test.f
rfluka -e n2test -N 0 -M 1 -p lead n2test195
rfluka -e n2test -N 0 -M 1 -p lead n2test197
The results are in the files: n2test195001.log, n2test197001.log
and n2test.pdf shows the graphs.
Heavy Ion Laboratory
ul. Pasteura 5A
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