From: Konstantin Batkov (email@example.com)
Date: Thu Sep 13 2007 - 14:18:28 CEST
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' <firstname.lastname@example.org>:
> 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.
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