Re: About simulating neutron propagation

From: Francesco Cerutti (Francesco.Cerutti@cern.ch)
Date: Mon Oct 08 2007 - 12:00:31 CEST

  • Next message: Yung-Shun Yeh: "Re: About simulating neutron propagation"

    Dear Yung-Shun,

    I have in fact to clarify that the choice of NEUTRONS as DEFAULTS' SDUM
    is just intended to perform the transport of low energy neutrons (<19.6
    MeV) within the multigroup treatment. So, coming back to your questions,
    it is suitable ONLY for LOW energy neutrons. Since I saw that in your case
    you have also neutron beams with energies > 19.6 MeV, for them you need to
    perform nuclear interactions that indeed NEUTRONS neglect. Then, a
    proper choice is either SHIELDINg or NEW-DEFA (not explicitly requested,
    and good for MANY purposes). In the latter case, to avoid electromagnetic
    treatment, just put the EMF card with SDUM=EMF-OFF and, to save further
    time, put PAIRBREM with WHAT(1)=-3.0.

    Moreover, in your input the EVENTYPE and MUPHOTON cards are useless as
    well.

    Finally, to perform one million histories, it is better to split them into
    more cycles/runs (rfluka allows you to perform independent cycles in
    sequence), this way you will have also the possibility of getting
    statistical errors comparing the unformatted results of different cycles
    with the standard postprocessing tools (e.g. usxsuw for USRBDX).

    Thanks a lot to Alberto for pointing out these issues.

    Cheers

    Francesco

    **************************************************
    Francesco Cerutti
    CERN-AB
    CH-1211 Geneva 23
    Switzerland
    tel. ++41 22 7678962
    fax ++41 22 7668854


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