Re: event by event low energy neutrons scoring

From: bottai@fi.infn.it
Date: Thu Nov 15 2007 - 10:15:59 CET

  • Next message: Giuseppe Battistoni: "Re: event by event low energy neutrons scoring"

      Dear Alberto ,

      my initial idea was to use mgdraw.f and hbook like in the
      example : http://lxmi.mi.infn.it/~battist/fluka_hbk/
       but then I read :

    "
    2) When the user is interested in the multigroup low energy neutron transport,
    SIMPLE HISTOGRAMMING, like the standard HBOOK case here described, IS
    MEANIGLESS.
    For the above cases, only the standard FLUKA output, followed, if needed, by
    offline post-processing prepared by the user, can avoid the introduction of
    technical mistakes."

      So I was a little worry about using mgdraw, non undestanding
      well what can be done to avoid problems and why exactly histogramming
      is not possible for such low-energy neutrons (creating an NTUPLE
      directly without having to reprocess output would be easier for me).

         Sergio

    Quoting Alberto Fasso' <fasso@slac.stanford.edu>:

    > On Wed, 14 Nov 2007, bottai@fi.infn.it wrote:
    >>
    >> I'd like to use Fluka but before starting
    >> I've the following question :
    >>
    >> I need to score , event by event , the low energy neutrons
    >> exiting from a calorimeter (or passing through a volume around
    >> it) , recording for each event the multiplicity
    >> and the energies of the neutrons. Is it possible or in some
    >> way this kind of scoring is meaningfull due to multigroup
    >> low-energy neutrons transport ?
    >>
    >> which is the best approach for such scoring , is it possible with
    >> EVENTBIN ?
    >>
    >> best regards Sergio Bottai
    >
    > You can use EVENTBIN, but take into account the following:
    > 1) The energy of the neutrons escaping from the calorimeter is
    > not known exactly, but is known only with a resolution equal to
    > the width of the energy groups
    > 2) EVENTBIN, like USRBIN, does not score the number of neutrons
    > per event, but the neutron tracklength in a specified bin (or
    > in a specified region, if you chose region binning)
    >
    > Remark number 1) is valid in any case, independent of the command
    > you use. The neutron energy is not known better than the group width
    > even inside the program itself.
    >
    > You can avoid the problem described in remark number 2)
    > by using instead USERDUMP and writing a user routine mgdraw.f.
    > In this case you can get the actual number of escaping neutrons,
    > doing some programming after ENTRY BXDRAW (boundary crossing)
    > and after ENTRY EEDRAW (end of event).
    >
    > Alberto
    >
    >
    > -- Alberto Fasso`
    > SLAC-RP, MS 48, 2575 Sand Hill Road, Menlo Park CA 94025
    > Phone: (1 650) 926 4762 Fax: (1 650) 926 3569
    > fasso@slac.stanford.edu
    >

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