Modifying the source code to reduce the amount of tracking

Development
1

Hi all,

I am trying to track all the generated particles in the simulation but only in certain cell_ids and material_ids.
It seems that for now, when you set tracks=True in the run, it saves all the tracks without any filtering option.
Could anyone please point me in the right direction where I can modify to save tracks in certain cells and materials?
I believe this could reduce the tracks.h5 file size drastically (depending on the situation of course).

Thank you!
Best,

2

I don’t think this is currently an option to save only specific tracks that go through a certain material.

The default is to save all particle tracks are to the h5 file and this can result in a large file.

It is possible to save particular particle id numbers to the with the max_tracks and track attribute of openmc.Settings

Filtering of tracks by material can be done as a post process with commands like this line of code from this example

tracks_in_water_material = tracks.filter(state_filter=lambda s:s['material_id'] == 42)
3

Hi Shimwell,

Thanks for the reply!

Right. So, I am trying to modify the source code.
It would be helpful if you or someone could point to the right files or directions.

Thank you.

4

Hi everyone,

I wanted to follow up on this thread to see if anyone could offer some guidance.

I’m currently working on a project that involves modifying the source code.
My aim is to record the tracks that pass through a specific material_id or cell_id.
The ultimate goal is to trace these tracks back to their origins, which I believe would be valuable for characterizing neutron detector properties.

As mentioned by Shimwell earlier, recording all tracks, as currently available, results in a large output that is both time-consuming to generate and process.
Therefore, I’m looking to implement a more targeted approach.

Could anyone advise me on which part of the source code I should modify to achieve this functionality?
Any pointers or insights would be greatly appreciated.

Thanks in advance for your help!

5

For source code modifications this is the file that would need changing.

You could alternatively filter tracks from the larger track file with this example

tracks_in_zirconium_material = tracks.filter(state_filter=lambda s:s['material_id'] == 82)
# writing a separate vtk file for the tracks that go through the zirconium material 
tracks_in_zirconium_material.write_to_vtk('tracks_in_zirconium_material.vtp')

tracks_in_water_material = tracks.filter(state_filter=lambda s:s['material_id'] == 42)
# writing a separate vtk file for the tracks that go through the water material 
tracks_in_water_material.write_to_vtk('tracks_in_water_material.vtp')

print(f'{len(tracks_in_water_material)} tracks in water and {len(tracks_in_zirconium_material)}')
6

Hi Shimwell,

Thank you so much for the suggestion!
Let me try this and come back!

Best,