The ambient equivalent dose of photon is too large

Dear expert
After the previous guidance of experts, I have successfully calculated the activity of radionuclides produced by 20MeV proton irradiating the copper target, and the ambient dose equivalent H * (10) of neutrons during irradiation,which is consistent with the paper results. However, in the cooling time of 1h after the irradiation stops, I calculated the ambient dose equivalent of photons is greater by more than two orders of magnitude than the paper,and it is much larger than the calculation result of empirical formula.I suspect there is something wrong with the decay parameters I set. Can you check my input file for me? The region of “sore” is detector.
room.flair (5.8 KB)
Proton induced radioactivity and neutron yields in tantalum__and copper using Monte Carlo simulation.pdf (598.6 KB)
The literature results are shown in the figure
but when the cooling time is 0, I calculated the result is 259pSv / s, and when the cooling time is 1H, the result is 55pSv / s

Thans for your help.

The photon spectra emitted by the radio activated targets Cu at 1 m at the end of 1 h of 10/20 MeV irradiation depicting the presence of photon energies as shown below, the first figure is the literature result ,I think my results are consistent with the paper results except for the points with large errors


when I change “decay cut” in raddecay card ,the ambient equivalent dose significantly reduced,I set decay cut as 350,it is close to the literature value。But I don’t think this method is correct. Is the price comparison consistent with the actual situation when its value is 0?

Dear @gao_han ,
I am giving a look at your flair file and the article. Here are my suggestions

  1. If the beam doesn’t have a ring profile you don’t have to set Rin = Rout in the second BEAMPOS card. I suggest you to remove that card and instead in the beam card select “Anular” shape with Rmin = 0 and Rmax = 0.25

  2. Make sure that your geometry really matches the one described in the article

  3. Since you have the prompt cut set to 99999.0 (which could be fine) you can set the decay cut to 10.0 or event 1.0 (decay_cut * 0.1 = transport energy cutoff multiplication factor for beta+, beta- and gamma decay radiation): in the former case the transport cut off would stay at the default 100 keV, in the latter it would be lowered to 10 keV. The cut at 350 keV that you mentioned is probably only in the prompt as you can see comparing figures 4 and 6.

Let me know how it goes so in case of questions/problems we can reiterate.

Dear Davide Bozzato
I want to confirm in my input file,when I set Rin = Rout in the second BEAMPOS,is it a ring source? Only select “Anular” shape with Rmin = 0 and Rmax = 0.25,is it a circular source?I want to get a a pencil beam of diameter 0.5 cm.
And when I set the decay cut to 10.0 or event 1.0,the ambient equivalent dose of photon is still too large,but the photon spectra emitted by the radio activated targets Cu at 1 m at the end of 1 h is are very close to those in the literature,maybe my geometry and material doesn’t matches the article or the author get wrong something,my photon fluence is lower than the literature results in most energy,but ambient equivalent dose is larger than the literature results,the value of this paper is not even 1 pSv / s, don’t you think it’s too low from Fig. 4?
Thank you for your help

Dear @gao_han,
By selecting “Anular” with Rmin=0 and Rmax=0.25 your beam will have a circular shape in the XY plane of diameter 0.5cm as it is stated in the table of the article. You can have a more detailed look at the Simple sources lecture.
I would not increase the decay cut because there is no point in neglecting the contribution of low energy photons to the ambient dose equivalent.
I’ll try to have a closer look to the dose values.


Davide Bozzato dbozzato
Thanks for your help,I have no problem