I am currently simulations an electron beam impacting a tungsten target to create bremsstrahlung photons, which impact a Ra target.
So far, I have scored Ra isotopes/primary (Ra-225,Ra-224,Ra-223) produced in the target using RESNUCLE.
I have also been able to determine the total number of fissions that occur in the radium due to photons using USRBIN and AUXSCORE.
However, I would like to determine the fission products spectrum in the Ra target, which I am unsure how to do. I have tried using USRTRACK to score the fluence vs energy, but I am unsure of this method. I could not find an explanation of how to do this so any help would be greatly appreciated.
You can indeed use USRTRACK selecting HEAVYION as particle type. If you want to filter the spectrum for particular products you can use the fluscw.f routine. In its entry in the manual it is explained how to use the USRDCI function to access their properties so you can discriminate.
Thank you for your response.
I’m afraid that did not work. These are the issues I am having:
I would rather not filter the products as I would like to know what would be produced as this is unknown to me. Rather I would like to get a gamma spectrum from the products. I have rather naively used AUXSCORE to do this as I am unsure of another way. I also tried to obtain a spectrum without the filter (AUXSCORE) and unfortunately both methods produced an all zero result (see 25MeV_e-_Ta_Ra226_pfis_1_30_sum.lis for results in first target) 25MeV_e-_Ta_Ra226_pfis_1_30_sum.lis (11.3 KB)
I also used RESNUCLE to determine the target products, but even with this very large number of histories the uncertainty is very high for the lower mass (A) products in the target 25MeV_e-_Ta_Ra226_pfis_1_30_sum.lis (11.3 KB)
Perhaps I am missing some physics? I have added ionsplitting, which was not used in these simulations to see if that makes a difference.
I have attached my input to hopefully make things clearer. 25MeV_e-_Ta_Ra226_pfis_1.inp (5.4 KB)
Thanks for the clarifications, I misunderstood your goals.
I assume then that what you want is the spectrum of the gammas coming from the radioactive decay of your radioactive products. If so, it is pretty straightforward and this lecture may help you.
First thing you need to do is to set up an activation simulation. You can check the details in the lecture but i.e. you need a RADDECAY card (activation mode), an irradiation profile (IRRPROFI, you have it already) and the decay times to be considered (DCYTIMES). For instance, if you would like to know the spectrum just when the irradiation stops, you would select a decay time of 0 s.
Then you should associate the decay times with your scorings using the DCYSCORE card. In your case you would need at least 2, one for RESNUCLEI and another one for USRTRACK. Since you want the spectrum of gammas, in the USRTRACK you just need to specify PHOTON as particle type.
The AUXSCORE card is not needed for this calculation.
Thanks a lot for your detailed comments and the lecture you provided. They were very helpful.
I see that in the lecture, because a cooling time is specified, this returns (in RESNUCLE) the activity of the isotopes produced in the target. But, would it be possible to determine the isotopic inventory at the end of irradiation in particles/primary using RENUCLE? This would be more meaningful for my applications because I also want to score the amount (particles/primary) after build up of the daughter nuclei produced (example Ac-225 from decay of Ra-225) when irradiation stops after 10 days of irradiation.
I noticed that if I don’t assign the DCYSCORE to the detectors, the result is as I want it but I think this is the instantaneous inventory, but I could be mistaken.
So basically I am looking for the entire inventory of isotopes produced (including Radium decay products) in the targets at the end of irradiation.
You cannot obtain directly from FLUKA the radionuclide inventory expressed in “number of radionuclides”. The reported result of RESNUCLEi is activity when performing an activation calculation, as you mentioned. Nonetheless, you can easily obtain the number of radionuclides using the activity results and the decay constant of your radionuclides.
Please note that build up and decay of the whole inventory is already taken into account in the FLUKA calculation.
Hope it helps,
Francisco
PS: thanks to @ctheis for the offline enriching discussion.