Re: energy conservation

From: Paola Sala (paola.sala@cern.ch)
Date: Wed Sep 12 2007 - 13:30:12 CEST

  • Next message: Paola Sala: "[Fwd: Re: shielding_distributions]"

    Hi

    If you compare total energies, you have to take into account also
    the total energy of the target nucleus in the initial state, and the
    total energy of the nuclear fragments in the final state, including the
    residual nucleus that will NOT exit from the target. This is indeed
    what fluka checks internally at each interaction.

    for instance, if you take a reaction like
      n,A --> 2n,A'
    where A=(A,Z) is the target nucleus and A'==(A-1,Z) is the residual
    nucleus, if you count only the exiting particles the balance will be
    1 GeV in input ( few MeV kinetic energy are enough)
    2 GeV in output (twice the neutron mass)
    Of course this is balanced by the mass difference between the target
    and residual nuclei ( I leave out binding energies....)

    even more striking : in a neutrino quasielastic interaction
    a few MeV projectile will give you a 1 GeV nucleon in the final state.

    Ciao
    Paola

     
    On Wed, 2007-09-12 at 12:57 +0200, Konstantin Batkov wrote:
    > Ciao Paola,
    >
    > I compare the sum of the TOTAL energy of the secondaries with the
    > TOTAL energy of the projectile. Maybe I miss some elementary thing,
    > but I do not understand how can this be.
    > For instance, when the kinetic energy of the proton projectile is 10
    > GeV, I get up to ~ 60 GeV in the sum of the total energy of
    > secondaries.
    > Actually, my problem is more complicated that shown here and I do not
    > see the way using only the FLUKA estimators. That's why I need to use
    > the BXDRAW entry. I sum up the total energy by this piece of code:
    > ENTRY BXDRAW ( ICODE, MREG, NEWREG, XSCO, YSCO, ZSCO )
    > if (MREG.eq.3 .and .NEWREG.eq.2) then
    > sum = sum + ETRACK
    > end if
    > RETURN
    > The value of "sum" is set to zero in the beginning of each event.
    >
    > Konstantin


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