Date: Fri, 14 Dec 2012 11:25:57 -0600
The scintillator is glowing everywhere because its surrounded by water
causing massive scattering of your proton beam, which creates secondary
showers causing the scintillator to create optical photons. In either
case, the scintillator should create optical photons - cherenkov radiation
when the scattered protons hit the screen or scintillate from the
x-rays/scattered protons created by the proton beam. You might even want
to enable Transition Radiation considering the protons will go from water
to plastic then back to water.
The attached screenshots are the USRBINs for Protons and Photons
Photons in the PRECISIOn default setting should have a production threshold
of 100 keV, so you would likely have even more photons with enough energy
to create light in the scintillator if that production threshold was set
lower. The >100 keV photons probably don't contribute much to the optical
photon production considering its thin plastic, where the energy deposited
is probably low. The lower energy ones not in the simulation are likely to
make the glowing even more prominent.
Hope that helps.
--Nick
On Fri, Dec 14, 2012 at 7:28 AM, Francesca Fiorini <
francesca.fiorini_at_oncology.ox.ac.uk> wrote:
> Dear Fluka users,
>
> I have a question about a simulation result. I am simulating a
> scintillator immerse in water crossed by a proton beam. Both scintillation
> and Cherenkov photons are activated.
> When I plot the results from usrbin the scintillator glows everywhere, not
> only where it is hit by the beam (or close). This seems to be an error, but
> I really do not know what the cause is.
> Even if I simulate only Cherenkov or only scintillation photons I have the
> same strange situation with the scintillator glowing all along its area
> (20x20 cm2).
> What am I doing wrong? Files are attached.
>
> Many thanks
> Francesca
>
> Dr Francesca Fiorini
> Gray Institute for Radiation Oncology and Biology
> Old Road Campus Research Building
> Off Roosevelt Drive
> University of Oxford
> Oxford, OX3 7DQ
> UK
