RE: Scoring number of elastic collissions

From: Vasilis Vlachoudis (Vasilis.Vlachoudis@cern.ch)
Date: Fri Mar 02 2007 - 11:22:37 CET

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    Dear Sunil,

    you have to be careful with the low energy neutrons (En<19.6 MeV), the
    routine that I've send doesn't apply to them. It only works down to 19.6
    MeV, and not below when the neutrons are treated with the group
    approach. Is true that you can activate point-wise treatment for some
    elements [LOW-NEUT, what(6) card] like Hydrogen, but then the event flag
    for scoring the elastic scattering is no longer the LELEVT, but rather
    the LLENSC for both elastic and inelastic. Otherwise, the stuprf for
    these neutrons will be called only when there is an event that generates
    a secondary particle in the stack i.e. proton recoil.

    Best Regards
    Vasilis

    -----Original Message-----
    From: Sunil C [mailto:sunilc@barc.gov.in]
    Sent: Friday, 02 March 2007 08:03
    To: Vasilis Vlachoudis
    Subject: Re: Scoring number of elastic collissions

    Hi

    Thanks a lot
    If let us say the medium is hydrogen in which i need to count, the
    energy of neutron is within the low energy group say 1 MeV then is it
    possible to do so by switching off the inelastic collision, switch on
    all elastic collisions by threshold card and not transporting the
    protons so that it does not escape the region. These can be counted with

    USRBIn card. The number of protons will be more or less equal to the
    fluence in the region. I may be wrong also because if not transported
    the whole energy is deposited in the region. But these will not give the

    number of collissions.

    Just a train of thought

    Best Regards
    Sunil

    Vasilis Vlachoudis wrote:
    >
    > Hi Sunil,
    >
    >
    >
    > I would do something like the following:
    >
    > I will use the stuprf.f routine to increase the particle variable
    > ISPARK (1,NPFLKA) for every elastic event, like:
    >
    > IF ( LELEVT ) THEN
    >
    > * Increment number of elastic scatterings
    >
    > ISPARK (1,NPFLKA) = ISPARK (1,NPFLKA) + 1
    >
    > END IF
    >
    > And then use the USERDUMP with a modified MGDRAW routine to dump the
    > ISPARK variable which at this level should become ISPUSR(1), based on
    > the coditions: 1:falls below threshold, or 2. exists the system
    >
    > * Write Neutrons
    >
    > IF (JTRACK.EQ.8) THEN
    >
    > IF (ICODE.EQ.31 .OR. ICODE.EQ.12) THEN
    >
    > * Stopping or below threshold (POSITIVE) Unit:50
    >
    > WRITE (90, *) ISPUSR(1)
    >
    > ELSE IF(ICODE.EQ.14 .OR. ICODE.EQ.23 .OR. ICODE.EQ.32) THEN
    >
    > * Escapping from the geometry (NEGATIVE)
    >
    > WRITE (90, *) -ISPUSR(1)
    >
    > END IF
    >
    > END IF
    >
    >
    >
    > Of course you have to activate the call to userdump and set the proper

    > cuts with the low-bias to stop the group treatment of the low-energy
    > neutrons
    >
    > like:
    >
    > LOW-BIAS 1.0 73.0 1 100
    >
    > USERDUMP 100.0 40.0 5.0
    > userdump
    >
    > OPEN 90.0
    > UNKNOWN
    >
    > neutcount
    >
    >
    >
    >
    >
    > In the routine I am using the sign on the number of scatterings to
    > discriminate if they fall below the threshold or they escape the
    system.
    >
    >
    >
    > Cheers
    >
    > Vasilis
    >
    >
    ------------------------------------------------------------------------
    >
    > *From:* owner-fluka-discuss@fisica.unimi.it
    > [mailto:owner-fluka-discuss@fisica.unimi.it] *On Behalf Of *Sunil C
    > *Sent:* Thursday, 01 March 2007 14:00
    > *To:* fluka-discuss@fluka.org
    > *Subject:* Scoring number of elastic collissions
    >
    >
    >
    > Hi All
    >
    > I would like to count the number of elastic collissions a fast neutron

    > undergoes before reaching the thermal energy. I see that this
    > information is scored in the MDSTACK. How do i extract these
    information?
    >
    >
    >
    > Best Regards
    >
    > Sunil
    >


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