How to define the new source in a two-step simulation correctly?

Source Definition
1

Dear expert,
I am so sorry to disturb you when I met a problem in a two-step simulation problem.
I am now doing a simulation: using 35MeV@2mA electron beam to bombarding a tungsten target, and then employ the neutrons and photons emitted to irradiated Zn plate to produce 67Cu.
In the first step, I set the beam intensity as 2mA(1.25E16p/s), 2E8 primaries were transported and generate a very huge number of particles(including photons and neutrons), ~15GB, namely the number as B.
In the second step, I set the parameter in the IRRPROFI card for the p/s as 1.25E16. and with the source particles produced in the first step by source card.
It did produce a result with unit Bq/cm3(the volume of all regions are set as 1 cm3), I doubt it is not right.
So my question is whether the parameter I set in the IRRPROFI card is right or not? I don’t think a fixed number here is right since the amount of neutrons and photons produced in the first step vary with time(residuals produced by electron bombarding tungsten target is increasing with time). How can I do such a simulation with two-step method? Or the two step method is not suitable for such a problem.

Best regards,

Yours jiangfeng
2023.06.27

3

Dear @wan,

Thank you for your question. In order to better assist you, could you please also upload your *.inp file?

The IRRPROFI card is typically used for radioactive decay calculations (more relate to activation and radiation protection), and not for prompt radiation. My question to you is which scenario are you interest in?

The results one obtains from FLUKA are per primary, so after your first step you should normalize your results to 2 mA in the post-processing.

Best,
Daniel

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