[Simulation question]: Are extremely long computation times expected when scoring ROS generated via proton irradiation through geant4-dna-chemistry?

[rcatalang]

Simulation question

I'm using geant4-dna-chemistry to score at different times (via SBS) the ROS generated by a proton beam in water. Using a standard PC the computation times seem extremely long, I haven't even progressed beyond the first history. This does not seem to be the case with an electron beam. Is this an expected issue?

Using geant4-dna-chemistry-_opt1 the computation times are more tractable but I get an error during the chemical stage:

-------- EEEE ------- G4Exception-START -------- EEEE -------
*** G4Exception : TIME_DONT_MATCH
issued by : G4MoleculeCounter::RemoveAMoleculeAtTime
Time of species e_aq^-1 is 1 ps while global time is -1 ns

*** Fatal Exception *** core dump ***
G4WT3 > **** Track information is not available at this moment
G4WT3 > **** Step information is not available at this moment
G4WT3 >
-------- EEEE -------- G4Exception-END --------- EEEE -------

G4WT3 >
G4WT3 > *** G4Exception: Aborting execution ***
G4WT1 >
-------- EEEE ------- G4Exception-START -------- EEEE -------
*** G4Exception : TIME_DONT_MATCH
issued by : G4MoleculeCounter::RemoveAMoleculeAtTime
Time of species e_aq^-1 is 1 ps while global time is -1 ns

*** Fatal Exception *** core dump ***
Aborted (core dumped)

TOPAS-nBio category

Chemistry

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[wgshin]

Hi, What kind of method you used for track segment selection ? Did you use primary killer function or small (µm-scale) volume ?

[rcatalang]

Your answer makes sense but within my geometry (sphere with radius of 10 µm) a 2.5 µm track segment seems too large. Is there a way to estimate the appropiate track segment length for a given geometry or is it simply something you need to test?

[wgshin]

It depends on your configuration. The radicals will be diffusing out with small size of target volume, or you could not specify your track energy with large size volume.
I'm using 3 µm-side volume based on small test (https://doi.org/10.1088/1361-6560/ad9ce2 Figure 5(b))

[rcatalang]

Thank you for your help. Just to be clear, by track segment length selection are you referring to this parameter:

d:Sc/Gvalue/KillPrimaryBasedOnTrackLength = 1 um

correct?

[wgshin]

Yes. This filter will kill your primary particle when the total track length exceed 1 µm.
If you want to select track segment using kill functions, please use infinite target volume instead (as like SBSGetGValue example).