Activation discrepancy with PHITS

Dear Francesco Cerutti

I am sorry to disturb you again. I got the results through FLUKA!
At present, I have a doubt, in terms of dose calculation, FLUKA and Phits results are basically the same, but in terms of activity calculation, the two MC have some gap. I would like to ask you, are these gaps caused by the different particle cross-section database? How can I close the gap between the two? Here is a screenshot of my specific parameters:

Below are the settings for the cut-off energy of the FLUKA
Below are the settings for the cut-off energy of the PHITS

If I sent the wrong post, please tell me, thank you! If you can solve this problem, it would be no better than that!


Dear @zhuhy21,

You posted this message on a thread about compilation with DPMJET, while it doesn’t refer to compilation problems. Please, contribute keeping this forum clean and create separate threads for separate topics.

If you want any help understanding the behavior of your code, you have to upload your input (.flair and .inp files and in case, all the other necessary files, like user routines), otherwise it is not possible to understand what is going on.

Sorry, this is my FLUKA input file as well as the source file
12C.flair (13.8 KB)
SOBP.dat (2.6 KB)
sourceSpectrum.f (9.8 KB)
This is my phits input file
碳离子dchain-grid.inp (10.7 KB)

Dear experts
When I calculate the radioactivity, the root cause is the inevitable difference between the two cores? Or did I miss my cut-off energy setting?

Dear zhuhuaiyu,

thank your for your post.

Please beware that we may help you on understanding the settings for FLUKA, but we cannot help to interpret or compare results obtained with other MC codes.

I have a few questions, as it is not entirely clear what you are trying to achieve.
What is the purpose of the EMFCUT and LOW-BIAS settings in your input file ? What is your final goal ?

A few observations already on your input file:

  • You scoring normalisation for the volume is not correct (7 x 7 x 7 is not the actual volume of your copper target)
  • This card is not required: PHYSICS 1000 1000 1000 1000 1000 1000PEATHRES

Kind regards,


Dear Markus

Good morning :sunny:
First of all, these days, I have thought about your question. When I multiplied the dose obtained by FLUKA by 1.602176462E-7, I finally found that the specific value was very close to the results obtained by PHITS in terms of dose!
Secondly, as for the significance of using these cards, my current idea is to define a lower neutron cut-off energy (10E-10 MeV), and eventually I have to use LOW-BIAS. For the optoelectronic cut-off energy, I used the default EMFCUT of FLUKA.

Finally, about the problem of volume normalization you mentioned, I think there is no problem with mine! Because the final obtained activity is divided by the volume of the copper target body, so that I can get the activity of a unit volume.
My ultimate goal is to get the activity of the radionuclide produced by the particle bombardment target, but now I feel if something is wrong with me, the activity calculated by FLUKA is much less than by PHITS!! To illustrate, I give you an example. PHITS calculates that the activity of the iron target at some point is 13000 Bq / cm3, but the value of FLUKA is 5700 Bq / cm3. So, my question is why do two MC doses work the same, but so much difference in activity?
I may have described a bit tedious, I’m sorry to let you wait so long! I look forward to giving me a relatively reasonable explanation, this is the system difference between the two MC cores? Or did I wrong with a specific FLUKA setting?


Dear Zhuhuaiyu,

we highly recommend to rely on the default setttings (here e.g. PRECISION) and only to modify specific parameters if there is a good reason for it to do so. Arbitrary energy cuts may be unphysical and alter the results in an undesired way. If you want to determine activity produced, I recommend to remove the EMFCUT and LOW-BIAS cards.

As stated in my previous message: We cannot help to interpret or compare results obtained with other MC codes.

The reason why your scoring volume is not correct (7x7x7) is that you cut out the collimation holes, which you need to deduce as well from your the volume used for the normalisation.

Kind regards,


Dear Markus

I know the cause of the problem, and although there are still some questions in my files, I want to take a closer look at the relevant content of the user manual again. If I can’t solve it, I’ll turn to the forum again.
Thank you for your guidances. I wish you every success in your work and family.