I’m very new at FLUKA and trying to build an RTG simulation with a cylindrical radioisotope source. I was wondering, is it possible to simulate/calculate the heating effects of a gamma beam source and heating transfer? Or is ENERGY option at USRBIN is enough to indicate the heating effect?
Also, I am having troubles with adjusting the beam source, DOSE-EQ values for the specified beam that I use seems low, how should I adjust the intensity of a radiation source? Is adjusting the volume of the cylindrical beam is enouh-gh or should I use other cards to correctly simulate a cylindrical gamma source?
With FLUKA, as you noticed, you can get energy deposition with a cartesian or cylindrical USRBIN -expressed in GeV/cm3 per unit primary weight (your primary particle). Then you should normalize your results multiplying by the photon intensity (rate). To get e.g. a power deposited per cm3, (W/cm3) you need to convert GeV to J (1.6022e-10).
For what concerns the photon source definition (not a radioisotope), you need the following cards: BEAM to define your primary beam – particles (photons) and their energy etc., BEAMPOS where you specify a cylindrical source (Type:CYLI-VOL) – with all dimensions Rin/Rout, Hin/Hout and the second BEAMPOS card with a center coordinates of your cylindrical source.
Normalization, as mentioned before, is done at the last step by multiplying your results by the photon intensity/rate.
If instead you want to define a radioisotope uniformly distributed in a cylinder, you need a BEAM card with ISOTOPE (particle) and HI-PROPE card with A,Z of your isotope, as well as two BEAMPOS cards as explained above. A RADDECAY card is then needed to let it decay.
Let me know if you need further help or explanation.
Best regards,
Elzbieta
So is it possible to get an output as temperature? Which AUXSCORE should I use, or what is the closest? And what do you mean by nomalize your results multplying by photon intensity, is there any in-software feature that I can merge two graphs?
No, it is not possible to get temperature as output. You can have an output as power deposited. Then it is up to you to convert this value in an information that it is useful to you. How to do it, is beyond the scope of this forum. I know that some users have used ANSYS for this type of calculation.
Normalization: FLUKA results are provided per single primary particle. If your beam is made of 1 single particle, than you’re done. Otherwise, you have to apply a normalization factor.
I was unable recreate the results and couldn’t find any documents about the issue. Could you possibly give me more information or instructions about getting an output in W/cm3 or W/kg?
Look at the manual for the USRBIN card. There you will find the note #5:
Energy deposition will be expressed in GeV/cm3 per unit primary weight. Doses will be expressed in GeV/g per unit primary weight. To obtain dose in Gy, multiply GeV/g by 1.602176462E-7.
You have to convert GeV to Joule, and then, knowing the characteristics of the beam, you can pass from Joule to Watt.