Re: [fluka-discuss]: What particle crosses a boundary

From: Alberto Fasso' <fasso_at_slac.stanford.edu>
Date: Thu, 10 Apr 2014 05:56:23 -0700 (PDT)

Hi Joe,

I am sorry, I suspected some programming error in your input file or in
your routines, but I couldn't find any. I still don't think it is a bug,
but it is always difficult to try to debug somebody's else's code.

There are only two things a bit strange I found. The first is that the number
of all entering particles (72835) is slightly larger than the sum of
individual enties (72819), and the numnber of all exiting particles (148958)
is slightly larger than the sum of individual exits (148922).
But that could be due to the fact that you printed only entries or exits
where jtrack was between -6 and 39. Could the missing ones have numbers
larger than 39? Unlikely, I think, but there are other strange things
happening here.
Another strange thing is that out of 100000 incident particles, only
72835 enter the target. I don't think that decay products could miss the
target.

Another remark: the really only one impossible case is that of a pi+ particle
producing a pi- (I am talking about your pi+ beam, I haven't looked at the
K0Long one). The few photons could be due to the rare case
pi+ -> mu+, nu, gamma (probability of the order of 2E-4 according to the
RPP, although I am not sure that it is implemented in FLUKA), or to
pi+ -> pi0, e+, nu (1 %)

I would suggest to put some additional coding in your mgdraw, trying to
intercept the 5 "strange" events when they happen (i.e. the 5 pi- entering the
target), and not only in the final global summary. When you intercept one, you
could print the number of the event (NCASE, but you must INCLUDE '(CASLIM)')
and as much other information as you can (e.g. other particles in the same
event, the generation of the particle (LTRACK), etc.) And if the particle
number is not between -6 and 39, to print it, or at least to flag it for
instance as being = 40.
Another help could be to improve the geometry dividing the vacuum into
an upstream, a downstream, and a lateral region, and checking from which
region the intercepted particle enters the target.

Alberto

On Wed, 9 Apr 2014, Joseph Comfort wrote:

> What is the status of this bug? I don't see any mention of a correction
> in the message of the latest release.
>
> Joe Comfort
Received on Thu Apr 10 2014 - 16:06:48 CEST