Dear expert, I would like to calculate the reaction cross-section of photons reaching 68 zinc and generating 67 copper through fluka. I will perform the calculation based on the file data after the calculation. He.inp (9.1 KB)
sigma = ASigma/(rhoN_A), where the inelastic scattering length = 1 /Sigma. Finally, the reaction cross-section is calculated to be 1.13E-52cm^2. This value is too small. I don’t know where the problem lies.
Meanwhile, the calculated specific activity is 2.2118E+11. The forum says it needs to be divided by the number of beam proton reactions. I don’t know how to determine this number
I hope the expert can help me solve it.
Thank you！
To get meaningful (rather than infinite) values in that standard output table, remove ELECTNUC from the PHOTONUC card.
Note that the formula will give you the reaction cross section, including all reaction channels, at the average beam energy. Therefore, no momentum spread should be input.
The former post, you refer to, mentions the nuclide yield obtained by RESNUCLEi, and not the specific activity (RADDECAY and associated cards are out of context for this purpose). For the related normalization, of course what matters here is the number of beam photon (and not proton) reactions. This is given towards the end of the standard output file as Number of stars generated per beam particle by PHOTON
The PEATHRES/IONSPLIT PHYSICS cards are obsolete since a while and should disappear from any input file.
I calculated the reaction cross-section of 68Zn(γ, p)67Cu as 2.29mb by dividing the proportion of 67 copper, 1.4886E-05, by 7.1839E-04 and then multiplying it by sigma. This is slightly higher than the cross-section I calculated through talys. I wonder if my calculation method is correct?
Meanwhile, I would like to continue to ask why the value of Number of stars generated per beam particle by PHOTON, 7.1839E-04, is not equal to the sum of the proportions of all generated nuclides, 0.00074664. The values in different out files are similar but not the same. Which value should I adopt, or should I add up the values in out and take the average?
Finally, I want to study the physical process of the 40MeV electron accelerator hitting the conversion target W to generate photons to irradiate 68 zinc to produce 67Cu. Is it unwise for me to turn on ELECTNUC? Or, when should I turn on ELECTNUC
The value you found appears to be consistent with the FLUKA curve I previously provided, where you can find the desired cross section at multiple energies with no need to recalculate it.
You should take the average over all cycles you used to produce the RESNUCLEi result.
Since you had a photon beam, I told you to remove ELECTNUC for the only purpose to get the photon inelastic scattering length in the output table. Otherwise, you can always keep it. In fact, electronuclear reactions (activated by ELECTNUC together with photonuclear ones) play a role in case of thin targets, where the production of bremsstrahlung photons is limited.
Dear expert,
1.Isn’t the RESNUCLEi result in the tab.lis file generated by PROCESS just the average value of multiple threads? In the process of calculating the reaction cross-section, it seems that the value of Number of stars generated per beam particle by PHOTON was not used. Is there a problem with my understanding?
I also want to study the reaction cross-section of electrons on 68 zinc. Is it the same method? Do we need to turn off the ELECTNUC.
Yes, the RESNUCLEi result produced by Flair post-processing is the average over multiple cycles. On the other hand, the normalization by the number of photon reactions (stars) - that is intended to calculate the cross section - is performed by yourself, hence you have to calculate its average over the concerned cycles. Note that FLUKA, as pointed out several times already, is not designed to extract microscopic cross sections, though.
In case of electrons, you will not get the actual 1/Sigma in the output table. Still, if you want to study the nuclide yield from electronuclear reactions, obviously you need to have ELECTNUC.
