# Re: Scoring total charge with USRBIN

From: Lucia Sarchiapone <Lucia.Sarchiapone_at_lnl.infn.it>
Date: Thu, 4 Jun 2009 10:49:36 +0200 (CEST)

Hi,

when you use USRBIN with particles such as BEAMPART, electrons, protons
and so on, what you estimate is the fluence (particle tracklength
density) of those particles.
The results are given in unit particle/primary/cm^2, where cm^2 comes
from the ratio of the tracklength (cm) to the volume (cm^3) of the bin.

If you want to "count" particles you can try to use a USRBDX estimator
and score the current of particles crossing the surface between two
regions (the first region could be a dummy one where the beam starts and
the second one the target).

Hope it helps,

Lucia

On Jun 02, 2009 04:08 PM, theodorekon_at_inp.demokritos.gr wrote:

> Dear FLUKA authors and users,
> we are trying to make a very simple simulation using FLUKA in order to
> calculate the total charge created in our volume by a beam of protons
> (or deuterons) of energy 0.5GeV. In order to do that we created a very
> simple RPP target (x=10,y=10,z=10) filled with our gas (argon 90%,
> butane 10%). For scoring we used a USRBIN card with 100 bins in each
> direction. The result is, if we're not mistaken, in
> electrons/primary/cm^3. To test the result we also used a second
> USRBIN
> card for scoring the beam particles. If we understand well then if we
> all the values from all the bins and multiply by
> the volume (which is 1000cm^3) we should get something which is less
> or
> equal to one. The problem is that we get more than one which means
> that for
> each primary (proton in our case) we count 2 or 3 beam particles in
> our
> volume which is even more strange if you consider the fact that we
> have a gas
> target so normally none of the beam particles should stop there. The
> total
> charge we get (if again we sum all the values from all the bins and
> multiply
> by the volume) is also much more than we expect. Most probably there
> is a
> problem with our understanding of the result or with the simulation's
> volume
> normalization. In any case we have also attached the input file.
>