From: Giuseppe Battistoni (Giuseppe.Battistoni@mi.infn.it)
Date: Mon Jan 22 2007 - 10:44:35 CET
>From Alberto Fasso:
don't worry: the "missing energy" means nothing wrong, it is
a honest physical quantity! It is what we call "Q" in nuclear
When you have an endoenergetic nuclear reaction, for instance a
(n,2n) reaction, you have a positive missing energy. It is missing
because which it has been transformed into binding energy of the final
When you have an exoenergetic nuclear reaction, for instance a
(n,gamma) or a thermal fission, you have a negative "missing energy".
That means, energy is not missing at all, but is created out of nuclear
In the end, FLUKA does its total energy balance, which can be positive or
negative. In a pure electromagnetic run, the missing energy is
practically zero. In a run with nuclear reactions, it can be positive or
negative. With a thermal neutron source or with fissionable materials
the missing energy can usually have a very large negative value.
With Pb and Ta, as in your case, a lot of energy is needed to break
the nucleus (think of all reactions having an energy threshold),
and the missing energy can be positive. The value you found of 6.3%
is not particularly high.
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