Dear Staffan
I suppose that the behaviour you are reporting is due to the step size in the transport. Have a look at the presentation in the advanced FLUKA course related to advanced settings:
https://indico.cern.ch/event/334606/contribution/9/attachments/653346/898375/AdvancedSettings2014.pdf
In particular by lowering the default value in the FLUKAFIX card the artefact should disappear. Have a try at the following
FLUKAFIX , 0.005, , , VACUUM, _at_LASTMAT, 1.
Greetings
Joachim Vollaire
From: owner-fluka-discuss_at_mi.infn.it [mailto:owner-fluka-discuss_at_mi.infn.it] On Behalf Of Staffan Engdahl
Sent: 07 January 2016 17:56
To: fluka-discuss_at_fluka.org
Subject: [fluka-discuss]: "Saw tooth" shaped energy deposition in submillimeter scoring volumes.
Dear FLUKA Community,
While scoring energy deposition by a carbon ion beam we observe an unexpected saw tooth shaped depth dependence when scoring in submillimeter thick discs. I attach two versions of the integrated depth dose plots and the related input card. The plots are generated by the plotting tools in Flair.
Don't mind the unnormalized ordinate values. On the horizontal axis, the depth in cm from the water phantom (cylinder) surface entry point is given.
The effect is more prominent in the plateau and decreases when nearing the Bragg peak, also the length of each dent is decreasing, indicating a stopping power related issue? There is no visible effect in the fragment tail. I should also mention that this effect is not present when running simulations with default settings for delta ray production and only appears when applying CSDA for all energies (DELTARAY threshold set higher than initial energy).
Do you have any explanation as to why this behavior appears? Is it an effect of the small scoring volume and step size related? Ionization straggling?
When reducing spatial resolution (increasing depth bin size), the effect is no longer visible.
Best regards,
Staffan Engdahl
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Received on Wed Jan 13 2016 - 11:19:55 CET