Semi-Analogue modes in both DCYSCORE and RADDECAY

Dear FLUKA experts:
Hello , I found there are Semi-Analogue modes in both DCYSCORE and RADDECAY while working on RIB experiments. Could you please explain the differences between them and guide me on how to choose the correct mode?


Dear lway,

Thanks for your question and welcome to the community!

When you set WHAT(1) in the RADDECAY card as >1 (Semi-analogue mode) each single radioactive nucleus is treated in a Monte Carlo way (random daughter nuclides are produced and random radiation is produced and tracked). However, this decay information will be scored by a given detector card only if there is also a DCYSCORE card with WHAT(1)=-1 (Semi-analogue) associated to it. Without it, no information coming from the radioactive decay will be scored (but only prompt radiation).

To get a deeper understanding, please have a look to the manual where RADDECAY and DCYSCORE cards are described. Notes at the end of the page might also be of help!

Let me know if I was not clear,

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Dear Marco,

Thank you for your helpful response and the links to the relevant sections in the manual. Your explanation of how the Semi-analogue mode works in RADDECAY and DCYSCORE cards was clear.

I apologize for the delay in my response, which was due to unforeseen circumstances. I appreciate your patience and understanding as I catch up with my work.

Regarding my previous question, I would like to know what happens if I select “active” mode in RADDECAY and choose “Semi-analogue mode” in DCYSCORE instead of “-1”? I would appreciate any clarification you can provide about the outcome in this case.

Thank you again for your help.

Best regards,


Dear Lway,

Sorry for my late reply. In the FLUKA manual such case is not documented, RADDECAY = active is always associated to a given DCYSCORE where the selected value is a defined cooling time. While RADDECAY = semi-analogue is always associated to a DCYSCORE = semi-analogue. My suggestion is to use these scoring cards as indicated by the manual.

Additionally, in the attached documents, you will find a flair file with a test with two scorers:

  • RADDECAY = semi-analogue associated with DCYSCORE = semi-analogue (correct use)
  • RADDECAY = active associated with DCYSCORE = semi-analogue

As you will see after running a simulation, the produced results are different, I would therefore suggest you not to use the second approach.


activation_exercise_solution_mod.flair (4.4 KB)

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Dear Marco,

Thank you for your response and for providing clarification on the usage of RADDECAY and DCYSCORE in the FLUKA manual. I appreciate your suggestion to follow the instructions in the manual and use the recommended scoring cards.

Lastly, I would like to extend my heartfelt appreciation for your contribution to the development of this discussion. Your insights and expertise have been invaluable to me, and I feel fortunate to have the opportunity to engage and learn from you.

Thank you once again for your assistance.

Best regards,

When RADDECAY = active, DCYSCORE = semi-analogue just gives the prompt contribution, identical to the scoring result without DCYSCORE at all.

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For completeness, flair file has been corrected and the cards PHYSICS/IONSPLIT and PHYSICS/PEATHRES have been removed.
activation_exercise_solution_mod.flair (4.3 KB)