5 GeV proton in the water phantom

Dear Experts of FLUKA,

I am going to obtain the depth dose distribution of monoenergetic protons (with energy 5 GeV) in a water phantom. The input file is attached.

As you can see in the input file, I only used the DEFAULTS card (PRECISIO) for the physics. Does the FLUKA code take into account all interactions to simulate proton beams in water?

Please specify which cards should be used to take into account all interactions for obtaining the depth dose distribution of protons with energy 5 GeV in water.

FYI: I am using FLUKA 4-3.1

Proton-5GeV.inp (1.1 KB)

Dear @MMR1,

Please, have a look at the hadronic physics lecture from the last Fluka Beginners’ course.
If you’re interest in some other specific process, maybe additional cards could be useful.
Also, please remember that on the forum support is provided only for the last released version. As of today, this is 4-3.4.

Hello @amario

Thank you for your reply.

In fact, I am looking to compare the results of FLUKA and GEANT4 in terms of depth dose distribution of 5 GeV protons in the water phantom.

The geometry used in both codes is completely the same, and in GEANT4 I used the reference physics of FTFP-BERT. However, the depth dose distribution obtained from the codes is different. My question is, what is the reason for this difference? Have I made a mistake somewhere in the input file of FLUKA? Is this difference due to the physical models or cross-sections used in these two codes?

I attached the Figure of depth dose distribution (total dose including the dose of primary and secondary particles) in JPG format, the input file and the output data of FLUKA, and the output data of GEANT4.

Could you please guide me to recognize the reason/s for this difference?


Proton-5GeV.inp (1.4 KB)
Proton-5GeV_21_plot.dat (246.2 KB)
output-Geant4.dat (232.2 KB)

I don’t see any evident problem in your Fluka input (as a side comment, the contribution to dose deposition of photonuclear, electronuclear, and mu pair production is not really significant).

Are you sure that the FTFP-BERT is the right physics list for this case? Which physics list is the most suitable for this use case is a question for the Geant4 forum.

Also, are you sure you’re comparing the same quantity? There might be some difference due to the volume over which you’re scoring and the mesh definition.

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Thank you @amario for checking the FLUKA input file.

I will definitely check the other physics lists of GEANT4.

The geometry, definition of the mesh, and the measured quantity are the same in both codes.

I observed a good agreement between the results of FLUKA and GEANT4 (FTFP-BERT) up to 3 GeV. But with increasing the energy the agreement was weaker, as you saw for 5 GeV. Do you have any idea in this case?

At 5 GeV/c, FLUKA changes physics model going from the resonance model to the Dual Parton Model (see the manual here).

I cannot comment on Geant4. You can ask the same question there.

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Thank you @amario for your time.