Re: Scintillator response

From: Alfredo Ferrari <>
Date: Thu, 14 May 2009 18:11:22 +0200

... adding to Giuseppe remarks.

yes you can get fairly reasonable recoil proton spectra, but you need:

a) to be sure you have no biasing (in particular no non-ananlogue
    neutron absorption), a DEFAULT card with sdum PRECISION should do
    the job. look for "fully anlogue run" or similar in the output
    to be sure
b) select pointwise (and explicit) recoil treatment for hydrogen
    (what(6)=1.0 in the LOW-NEUT card). Check the output for a message
    that it is indeed activated
c) set a reasonably low proton transport threshold with PART-THRESH (the
    default one with PRECISION could be already low enough)
d) check your scintillator dimensions, if it is big enough you will
    get anyway sooner or later all energy deposited
e) take care of removing the non-proton energy losses, mostly kerma
    energy depositions due to interactions on Carbon by
    a) setting TCQUENCH parameters for proper (light) quenching for
       your scintillator
    b) or using a COMSCW routine
f) score with EVENTBIN rather than DETECT. DETECT is rather rigid,
    it does not allow for user selection with COMSCW, and it doesn't
    allow for quenching

                          Best regards

| Alfredo Ferrari || Tel.: + |
| CERN-EN/STI || Fax.: + |
| 1211 Geneva 23 || e-mail: |
| Switzerland || |

On Thu, 14 May 2009, Giuseppe Battistoni wrote:

> Dear Jean-Emmanuel
> if you score total energy deposition you see more than just proton recoil
> (de-excitations etc.) Deposition from proton recoil can be scored
> selecting depoistion from just protons.
> You can do that with a separate detector using one of the selection
> method described in the manual (user routines fluscw or comscw or AUXSCORE
> data card).
> However notice that the detailed production of proton recoil
> exists in FLUKA (for neutrons below 20 MeV) only for few selected
> elements. Hydrogen is one of these (look into the manual for reference)
> Giuseppe Battistoni
> Jean-Emmanuel Groetz wrote:
>> Dear Fluka experts,
>> I would like to calculate the recoil proton energy spectrum in an
>> organic scintillator, such as BC501-A, NE213 or stilbene after neutron
>> irradiation (monokinetic beam) between 2 and 15 MeV.
>> Since the n-p scattering is isotropic in the center of mass system in
>> this energy range, the energy spectrum of the recoil protons should have
>> a rectangular shape between 0 and En. Due to edge effects, the spectrum
>> should have a decreasing slope (without taking into account the
>> nonlinear light output with energy).
>> In order to get it, I used the DETECT card to score the energy
>> deposition in my region of scintillation. But this spectrum showed a
>> strong peak near the incident energy of neutrons. I can mentioned that
>> the shape of the spectrum seems to be correct at 70 MeV for example.
>> Does anybody succeed in this kind of simulation with Fluka ?
>> Did I misunderstand the results ?
>> Thanks for your help.
>> Jean-Emmanuel
Received on Thu May 14 2009 - 19:59:06 CEST

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