How to replicate the Ionisation Cluster Size Distributions from Ramos-Mendez et al. 2018 - "Fast calculation of nanodosimetric quantities..."

[j-m0rris]

Simulation question

Hi,

I am attempting to replicate the ICSD from Ramos-Mendez et al. 2018 (Figure 2, top left) and would like some clarification on some aspects of the simulations performed to generate them.

I am using the example setup for the 1800 random cylinders inside the cylindrical envelope from Faddegon et al. 2023 with the uniform beam being the length of the cylindrical envelope and directed from one side of the cylinder.

I am however unclear as to:

1. What physics model was used for these simulations (we used 'TsEmDNAPhysics')?
2. Any variance reduction used?
3. How many histories used? I used 100,000.

My differing simulation parameters are:

1. Beam (not the same as either three setups in Ramos-Mendez et al. 2018, but is the one from Faddegon et al. 2023).
2. Geant4/Topas version (I am using V11.1.3).
3. Physics model?
4. Histories?
5. Scoring? I am using the 'ClusterSizeInRandomCylinders' scorer. It appears as though this is only scoring ionisations from secondary electrons, is this true? Is this the right way to go about the scoring? Alternatively, I have tried to use a pTuple filter to score all events and then filter ionisations in post-processing with MATLAB.

Thus, we know our results will be different. However, if you can clarify these aspects, we will be able to get closer to the result from Ramos-Mendez et al. 2018. Our results were similar in that as particle/ion weight increased (e.g. proton -> alpha -> Lithium-7) so too did the probability of low cluster sizes, at least for "low" cluster sizes (< 15). However, we see quite large cluster sizes occurring and different distributions beyond a cluster size of around 15.

Let me know if you need any more information to assist me (e.g. input files, images of ICSD's etc.).

Thanks.

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