Re: Neutron and Pion USRTRACK results.

From: Alfredo Ferrari (alfredo.ferrari@cern.ch)
Date: Sun Dec 03 2006 - 18:10:47 CET

  • Next message: Tang, Alfred: "RE: Neutron and Pion USRTRACK results."

    Dear Lindley

    a few comments, I hope useful:

    a) I checked that Fluka2006.3 and Fluka2005.6 give with your input
        results for neutrons and pions which are identical within the errors
        (as it should be since nothing changed in between the two versions
        about muon photonuclear interactions) -> if the results are different
        from expected or obtained by others the reason must be in your setup
    b) your setup has monoenergetic muons of 285 GeV. I suppose this is the
        <average> energy of a muon spectrum underground, which usually
        extends from "zero" to an energy higher than the average. Using a
        monoenergetic beam instead of the proper spectrum can ingenerate
        differences, particularly for those processes (ie muon- capture
        at rest) which don't scale at all with energy. If my supposition is
        wrong forget my comment
    c) you start your beam just in front of your target, again if the problem
        is referring to some underground situation, the rock before, aside,
        and after must be modelled for 1-2 metres minimum (particularly the
        one before), if not you miss all neutrons coming from interactions
        in the rock. The effect is more or less large depending on your
        detector size, in your case it should not be obviously negligible
        but it should make factor of a few as well
    d) pi+ *must* be higher than pi- for your problem. You have a LIQUIDS
        material which is mostly hydrogen, see below the output of FLUKA
           Material Number Atom content Partial Densities

           CARBON 6 0.41440E-01 0.26436
           HYDROGEN 3 0.95856 0.51318
        Is it possible you made it wrong, that is you wanted a 1:2
        C:H ratio in atom content and not in density?? Scintillators
        have typical C:H ratio of 1:1 to 1:2 in atoms usually! If
        so it could explain most of your problems, the correct COMPOUND card in
        that case would be (note the signs!)
    COMPOUND +0.34 6.0 +0.66 3.0 0.0 0. LIQUIDS
        This is very likely to be the culprit

    e) There is a contribution from real photon photonuclear interactions
        (that is photons coming from muon pair production, bremsstrahlung and
        delta rays can make (gamma,n) reactions). For a hadronic shower their
        contribution is usually negligible, for muons it can be of some
        relevance since thru bremss+pair+delta they expend much more energy
        than the one by virtual photonuclear interactions. To switch on real
        photon photonuclear interactions look at the PHOTONUC card in the
        manual (I would be surprised it makes more than a 10% contribution
        however...)
    f) Your input file is for 10000 muons. I needed 200000 to get n and
        pi statistics at 10% or worse level on totals!! Either you run for
        huge numbers of primaries, or you activate interaction biasing
        to improve statistics (see LAM-BIAS). In the latter case, please
        be careful in your mgdraw generated file that particles carry
        weights which will be different than 1 and in general different
        from one to the other (the FLUKA built-in scoring facilities like
        USRTRACK and USRBIN account automatically for this)

                          Ciao
                         Alfredo

    On Fri, 1 Dec 2006, Lindley Winslow wrote:

    >
    > --Apple-Mail-12--108175957
    > Content-Transfer-Encoding: 7bit
    > Content-Type: text/plain;
    > charset=US-ASCII;
    > delsp=yes;
    > format=flowed
    >
    > Hello all,
    >
    > I was comparing my results from the attached setup with results
    > others has obtained with an older version of FLUKA and a similar
    > setup. The most obvious difference is my neutrons are an order of
    > magnitude low and pi+ higher relative to pi-. I was wondering:
    >
    > 1) Had I correctly setup the PHYSICS model for a problem where
    > residual nuclei scoring was important?
    > 2) I thought I understood from the manual that LOW-MAT or LOW-NEUT
    > cards were not needed for this setup and that low energy neutrons
    > would be transported by default.
    >
    > I am running:
    > FLUKA2006 Version 3.0 Sep-06 by A. Ferrari DATE: 12/ 1/ 6 TIME:
    > 19: 5:41
    >
    > Thank you,
    > Lindley
    >
    >
    > --Apple-Mail-12--108175957
    > Content-Transfer-Encoding: 7bit
    > Content-Type: application/octet-stream;
    > x-unix-mode=0640;
    > name=cylinderLSExperiment.inp
    > Content-Disposition: attachment;
    > filename=cylinderLSExperiment.inp
    >
    > *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
    > TITLE
    > Simple Muon Spallation Monte-Carlo in LS target.
    > *...+....1....+....2....+....3....+....4....+....5....+....6....+....7...+...8
    > BEAM 2.85E+02 MUON-
    > BEAMPOS 0.0 0.0 -50.0
    > *
    > GEOBEGIN COMBNAME
    > 0 0 A simple LS target inside vacuum
    > RPP body1 -5000000.0 +5000000.0 -5000000.0 +5000000.0 -5000000.0 +5000000.0
    > RPP body2 -1000000.0 +1000000.0 -1000000.0 +1000000.0 -100.0 +1000000.0
    > RCC body3 0.0 0.0 0.0 0.0 0.0 1000.0 500.0
    > * plane to separate the upstream and downstream part of the target
    > *XYP body4 2.5
    > END
    > * black hole
    > regBH1 5 +body1 -body2 -body3
    > * vacuum around
    > regVA2 5 +body2 -body3
    > * LS target 1st half
    > regBE3 5 +body3
    > * LS target 2nd half
    > *regBE4 5 +body3 -body4
    > END
    > * The next is an example of geometry debugging:
    > *GEOEND 150. 75. 220. 30. 0. -220.DEBUG
    > *GEOEND 120. 1. 110. 0. 0. 0. &
    > *STOP
    > * Normal End.
    > GEOEND
    > *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
    > * Here defines materials and Compounds for LS
    > *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
    > *1) Hydrogen
    > MATERIAL 1.0 1.00794 0.0000837 3.0 1.0 HYDROGEN
    > *2) Carbon
    > MATERIAL 6.0 12.0107 2.00 6.0 CARBON
    > *3) Oxygen
    > MATERIAL 8.0 15.9994 0.00133 8.0 OXYGEN
    > * liquid scintillator
    > MATERIAL 0.0 0.0 0.77754 26.0 0.0 0. LIQUIDS
    > COMPOUND -0.34 6.0 -0.66 3.0 0.0 0. LIQUIDS
    > * LS target, 1st and 2nd half
    > ASSIGNMAT LIQUIDS regBE3
    > * regBE4
    > * External Black Hole
    > ASSIGNMAT BLCKHOLE regBH1
    > * Vacuum
    > ASSIGNMAT VACUUM regVA2
    > * Turn on the Physics Model, What is SCORE doing?
    > *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
    > EVENTYPE 0.0 0.0 2.0 0.0 0.0 0.DPMJET
    > PHYSICS 3.0 EVAPORAT
    > PHYSICS 1.0 COALESCE
    > *
    > * Activates Residual Nuclei scoring
    > *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
    > RESNUCLEI 3.0 34.0 regBE3
    > RESNUCLEI 1.0 35.0 regBE3
    > RESNUCLEI 2.0 36.0 regBE3
    > *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
    > * Cartesian binning of the pion fluence inside and around the target
    > * R-Z binning of the neutron fluence inside and around the target
    > USRBIN 11.0 NEUTRON -50.0 500.0 0.0 1000.nuFluBin
    > USRBIN 0.0 0.0 0.0 50.0 1.0 1.0 &
    > * R-Z binning of the neutron fluence inside and around the target
    > USRBIN 11.0 NEUTRON 51.0 500.0 0.0 1000.nuFluBin
    > USRBIN 0.0 0.0 0.0 50.0 1.0 1.0 &
    > * R-Z binning of the neutron fluence inside and around the target
    > USRBIN 11.0 ELECTRON 52.0 500.0 0.0 1000.nuFluBin
    > USRBIN 0.0 0.0 0.0 50.0 1.0 1.0 &
    > * R-Z binning of the energy deposited inside and around the target
    > USRBIN 11.0 ENERGY -53.0 500.0 0.0 1000.nuFluBin
    > USRBIN 0.0 0.0 0.0 50.0 1.0 1.0 &
    > *...+....1....+....2....+....3....+....4....+....5....+....6....+....7...+...8
    > USRTRACK 1.0 NEUTRON 62.0 regBE3 1.0 1000. nuTrck
    > USRTRACK 1. 0. &
    > USRTRACK 1.0 ELECTRON 63.0 regBE3 1.0 1000.eminTrck
    > USRTRACK 1. 0. &
    > USRTRACK 1.0 POSITRON 64.0 regBE3 1.0 1000.eposTrck
    > USRTRACK 1. 0. &
    > USRTRACK 1.0 PHOTON 65.0 regBE3 1.0 1000.photTrck
    > USRTRACK 1. 0. &
    > USRTRACK 1.0 PROTON 66.0 regBE3 1.0 1000.protTrck
    > USRTRACK 1. 0. &
    > USRTRACK 1.0 PION+ 67.0 regBE3 1.0 1000.piplTrck
    > USRTRACK 1. 0. &
    > USRTRACK 1.0 PION- 68.0 regBE3 1.0 1000.pimnTrck
    > USRTRACK 1. 0. &
    > * Dump all particles.
    > * Notice slightly different bar to get formatting right.
    > USERDUMP 200.0 37.0 1.0 1.0 SRCEPART
    > * This one is from USDRAW
    > OPEN 71.0
    > usrdraw.txt
    > *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
    > RANDOMIZE 1.0
    > *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
    > START 10000.0
    > STOP
    >
    > --Apple-Mail-12--108175957--
    >

    -- 
    +----------------------------------------------------------------------------+
    |  Alfredo Ferrari                ||  Tel.: +41.22.767.6119                  |
    |  CERN-AB                        ||  Fax.: +41.22.767.7555                  |
    |  1211 Geneva 23                 ||  e-mail: Alfredo.Ferrari@cern.ch        |
    |  Switzerland                    ||          Alfredo.Ferrari@mi.infn.it     |
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