Re: Help with pion multiplicity

From: paola sala (
Date: Sun May 06 2007 - 14:03:48 CEST

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    1)The "target" in your input is much too thick, and
    the beam is loosing a lot of energy in it:
    you can see at the end of the out file that 88% of
    the beam energy stays in the target.
    Therefore, you are not measuring the production
    at the beam energy, but over all the range
    from the beam energy to zero.
    2) about cross sections. The one you are referring to are
    NOT the "nuclear" cross sections in general,
    they are the cross sections for low energy neutron
    transport ( low energy means below 20 MeV ).
    Low energy neutrons have no influence on the problem you
    want to simulate. Therefore, it
    would be much better to have the correct target material.
    To avoid crashes at initialization because of the missing
    neutron lib, you can fake the code
    with the LOW-MAT card, associating to LANTANIUM wichever
    cross section you wish:
    for instance


    and discard all the low energy neutrons by

    LOW-BIAS 1.0

    On Fri, 2007-05-04 at 15:26 -0700, Norman Furlong wrote:
    > Hi,
    > I signed up for the May Fluka course in Houston and have been running some
    > simple pion multiplicity experiments to get up to speed prior to the
    > week-long training. I would like to reproduce the results from this paper
    > (attached), particularly figs 1 & 2, but have not yet been able to. I
    > understand the physical setup will be different, but I would expect to see
    > similar slopes from my runs.
    > Can you please look at a sample file I used and make recommendations? This
    > one (pa9a.inp) is for a 740MeV La beam onto a Ba target. I¹m using Ba as a
    > target instead of the La in the paper since I didn¹t see nuclear
    > cross-section data for La in the Fluka libs. I also included an output file
    > (pa9a001.out). I removed the XY plane so I could measure all the particles
    > leaving the target block, but I'm not sure I'm using the most appropriate
    > detector for this experiment.
    > Thanks,
    > Norman

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