Re: energy conservation

From: Konstantin Batkov (
Date: Thu Sep 13 2007 - 14:18:28 CEST

  • Next message: Paola Sala: "Re: energy conservation"


    I was trying to score the sum of total energy using the USRYIELD card:

    USRYIELD 1413.0 201.0 21.0 R_TARGET R_VAC 1.0 etotal
    USRYIELD 20. 0.0 1.0 3.1415926 0.0 3.0 &

    For simplicity, I set the target material to VACUUM and primary particle to
    PHOTON, so it is obvious to obtain the sum of the total energy of all
    particles escaping the target: it must be equal to E0.
    Instead, I have found out that in this case the result does not depend on
    the primary energy. I concluded that USRYIELD always gives 1/(dE*4*PI).
    At the same time I get the correct result when I calculate this value by the
    code in BXDRAW.

    I am sorry for these stupid questions, but please tell me where am I wrong.
    My source code and the input file corresponding to this letter can be found


    2007/9/12, Alberto Fasso' <>:
    > I haven't looked at your input yet, but in principle it is not
    > impossible to get more energy than carried by the projectile.
    > It is the famous "nuclear energy" :-), or more technically,
    > the effect of exoenergetic reactions. Fission is the most
    > popular, but there are others, for instance (n,gamma). The
    > extreme case I have found myself was with a source of thermal
    > neutrons. The projectile energy was close to zero, but the gamma
    > energy produced was of the order of several MeV. By the way,
    > I wanted to score an energy spectrum (with USRBDX), and I used
    > the default to define the upper and the lower end of the spectrum.
    > Since USRBDX as a default sets the maximum energy equal to that of
    > the BEAM, I got all zeroes!
    > Just as a suggestion, why don't you use the built-in facilities
    > to do this type of calculation? USRYIELD with particle type = 201
    > and a single energy and a single angular intervals can give you the
    > total energy escaping the target. User routines are always
    > difficult to debug and should be used only in extreme cases
    > when the same result cannot be obtained by input file only.
    > Alberto

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