Hello @sy2119104,
Thanks for providing this additional input. It seems to me that you are comparing two different things in the way you defined them here:
- On one hand you have the yield obtained through a RES-NUCLEi scoring, this will have as output the total amount of residual nuclei produced when fully de-excited to ground or isomeric state per cubic centimeter per primary, i.e. no time dependence whatsoever.
- On the other hand you have the activity which will have as output the activity at the requested DCYTIMES, which is given as Bq (so decays/s) per cubic centimeter per primary. These you sum up in the first five seconds only, however C-11 for example has a half life of around 20 minutes … .
The specific decay process indeed enters in the game here as you correctly mentioned. In your plot you see as well that for example C-11 has the highest contribution to the yield but much lower to the activity. Please also check carefully the RES-NUCLEi documentation and notes to make sure the physics settings are correct for this problem. To ensure you are comparing the same quantity perhaps may I suggest you only look at this post on activation and the use of the usrrnc.f routine which could provide you with additional information you need? For more information I’m also happy to recommend you to further check the course material of the FLUKA topical course on radiation protection.
Best regards, hope it helps,
Andreas