Re: energy conservation

From: Paola Sala (
Date: Fri Sep 14 2007 - 09:33:41 CEST

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    Setting what(2)=201 in the USRYIELD or USRBDX card gives
    as a result the distribution of particles as a function of the
    variables chosen by what(1). That is, a vector containing for each
    energy/angle interval the number of particles that carry this energy at
    this angle. If you take one interval in energy and angle, the result is
    the total number of particles crossing the surface (apart from
    normalization factors). Parenthesis: if one asks for fluence instead of
    current, the number will be inverse-cosine-weighted.

    To score kinetic energy fluence instead of particle fluence, set
    what(2)=208 or what(2)=ENERGY . The normalization factors will be the


    On Thu, 2007-09-13 at 14:18 +0200, Konstantin Batkov wrote:
    > Hallo,
    > 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 here:
    > Konstantin
    > 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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