Dear Ryan,
I have run your example and I think that the effect that you noted
is an artifact of the stepping algorithm. This is similar to the
effect on the full Bragg peak plot, as noted for example in this
previous discussion in the forum:
http://www.fluka.org/web_archive/earchive/new-fluka-discuss/2702.html
In your case, you are letting FLUKA choose the stepsize, but
this requires a careful treatment of all related processes,
i.e. energy loss and multiple Coulomb scattering, to have
reliable results.
To achieve this you can, for example, force a smaller step size
with the FLUKAFIX card. If you add the card:
FLUKAFIX 0.005 WATER WATER
you will produce a smoother plot. You can find more information on
this topic in the slides of the FLUKA course (see pag. 35 onwards)
at the address:
https://indico.cern.ch/event/604018/contributions/2435670/attachments/1395464/2242768/16_Ionization_and_Transport_2017.pdf
By the way, in your input I would remove the IONFLUCT card (straggling
was off ) and use one of the DEFAULTS settings (for instance
PRECISIOn) to define production and transport thresholds.
I hope this helps.
Best,
Andrea
> Andrea,
>
> Thank you for your reply. Here is input file. I have also attached a
> screenshot with more accurate formatting.
>
> *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
> TITLE
> Secondary proton energy deposition in a water phantom
> *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
> BEAM -0.2288
> PROTON
> BEAMPOS 0.0 0.0 0.0
> *
> GEOBEGIN
> COMBNAME
> 0 0 Water target inside vacuum
> RPP body1 -500000.0 +5000000.0 -500000.0 +500000.0 -500000.0 +500000.0
> RPP body2 -100000.0 +1000000.0 -100000.0 +100000.0 -100.0 +100000.0
> RPP body3 -200.0 +200.0 -200.0 +200.0 0.0 +200.0
> END
> * black hole
> regBH1 5 +body1 -body2
> * vacuum around
> regVA2 5 +body2 -body3
> * Water target
> regWA 5 +body3
> END
> GEOEND
> *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
> *MATERIAL
> WATER
> *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
> * Water target
> ASSIGNMAT WATER regWA
> * External Black Hole
> ASSIGNMAT BLCKHOLE regBH1
> * Vacuum
> ASSIGNMAT VACUUM regVA2
> *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
> * e+e- and gamma production threshold set at 10 KeV
> EMFCUT -0.000010 0.000010 1.0 WATER
> PROD-CUT
> *MCSTHRESh -1.0 -1.0
> IONFLUCT -1.0 -1.0 WATER WATER
> *MULSOPT 10001.0
> GLOBHAD
> *PHYSICS 0.00000001
> PEATHRES
> *PHYSICS 0.0 -1.0
> RQMDFLAG
> *PHYSICS 0.0
> EVAPORAT
> *DISCARD 7 8
> *THRESHOLd 1.0 1.0
> USRBIN 11.0 228.0 +62.0 10.0 0.0 50.
> hadrons
> USRBIN 0.0 100.0 0 500.0 &
> *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
> RANDOMIZE 1.0
> *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
> START 1000000
> STOP
>
> On Mon, Nov 27, 2017 at 1:34 AM, Andrea Fontana
> <andrea.fontana_at_pv.infn.it>
> wrote:
>
>> Hello Ryan,
>> could you please send your input file, so that we can check it?
>>
>> Andrea
>>
>>
>> Il 27/11/2017 06:29, Ryan Brosch ha scritto:
>>
>>> Dear FLUKA experts,
>>>
>>> I am scoring a monoenergetic, 228.8 MeV proton beam incident on a water
>>> tank. I am scoring dose deposited with USRBIN with bin size 1mmx1mm,
>>> radial
>>> symmetry, thusly
>>>
>>> USRBIN 11.0 228.0 +62.0 10.0 0.0 50. hadrons
>>> USRBIN 0.0 100.0 0 500.0 &
>>> *...+....1....+....2....+....3....+....4....+....5....+....6
>>> ....+....7....+....8
>>>
>>> The central axis dose versus depth should be smooth. However, there are
>>> discontinuities.
>>>
>>> Any idea what the problem might be? I don't think these discontinuities
>>> are physical.
>>>
>>> Thanks very much,
>>>
>>
>> --
>> ========================================================================
>> Dr. Andrea Fontana tel: +39 0382 987991
>> Istituto Nazionale fax: +39 0382 423241
>> di Fisica Nucleare
>> Sezione di Pavia e-mail: andrea.fontana_at_pv.infn.it
>> Via Bassi 6 web : www.pv.infn.it/~fontana
>> 27100 PAVIA, Italy
>> ========================================================================
>>
>>
>
>
> --
> Ryan Brosch
> Ph.D Candidate
> Department of Physics
> Arizona State University
>
--
========================================================================
Dr. Andrea Fontana tel: +39 0382 987991
Istituto Nazionale fax: +39 0382 423241
di Fisica Nucleare
Sezione di Pavia e-mail: andrea.fontana_at_pv.infn.it
Via Bassi 6 web : www.pv.infn.it/~fontana
27100 PAVIA, Italy
========================================================================
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Received on Mon Nov 27 2017 - 18:25:16 CET