Dear FLUKA experts,
I am running a simulation where a proton target and an electron target are placed in separate Vaccum chambers and there is another service chamber. And I have to design a downstream of each target and calculate the prompt ambient dose rates, the neutron ambient dose rates, and the residual ambient dose rates inside the service chamber that is in between the two chambers that contain targets. The input is attached here with please help me that how can I use and add scoring cards.
shielding.inp (8.3 KB)
Dear FLUKA experts,
I had a look at your input and I see that the geometry is not finished, there is plenty of errors.
I advice you to have a look at the slides from the beginner course, particularly at the lecture about geometry (in order to fix your geometry) and the lecture about scoring (to understand how they work).
Im simulating a geometry where a proton beam of 800GeV and 500kW is runs along z-axis (positive direction) and is 10cm upstream from the target. Also along z-axis but in opposite direction an electron beam of 500MeV, 1MW and 10mA runs along negative z-direction. Both the targets are placed in separate 2cm3 vacuum chambers and there’s a chamber in between those two chambers called service space with 2cm3 volume. My purpose of this simulations os to design a shielding downstream each target to mitigate the prompt ambient dose rates inside the service space.
For the scoring of neutron dose rate I use USRBIN with X-Y-Z and used DOSE-EQ with dimensions of service space and then to score the neutron dose I used AUXSCORE card and select the part. Neutron and the results of USRBIN were multiplied by the beam intensity and 3600E-6 for conversation to uSv/h. The same procedure was done for ambient dose of proton beam. Similarly for residual dose rates I used the RESNUCLE card with Semi-Analogue and for this I activated EVAPORAT. With heavy fragments and COALESCEnce in physics cards. Is it correct? Or I need some other cars for this?
As pointed out by @amario, it is a difficult to judge from the input file you provided, specifically considering that there the only scoring card present is not properly filled in.
The general approach you have described seems reasonable: you need AUXSCORE if you want the separate contribution of neutrons and protons, while scoring DOSE-EQ with no AUXSCORE associated to the corresponding USRBIN will give you the ambient dose equivalent from all the particles.
Yes, for residual nuclei estimation you should have evaporation and coalescence activated. For residual dose rate calculations the more correct approach would be to treat radioactive nuclei in an analogue way and adding the irradiation profile (and cooling time) as explained for example in the activation lecture.
Please take your time to digest the material and feel free to come back to us in case of further inquiries.
shielding 99(1).inp (9.2 KB)
I had worked on it and removed the errors in geometry and also run it successfully. The data files were also processed successfully without any error. But when I plot the the results of USRBIN I got the following error
"color axis has cb coord of -1 must be 0 for log scale’
What does it mean and how it can be resolved.
you still have some geometry errors (multiple defined regions) which you can easily spot and correct with the Flair. Additionally, the second SPOTPOS and SPOTDIR cards do not have any associated beam spot number (which should be 2 in your case) and RADDECAY should be in Active mode (not Semi-Analogue) since you have an irradiation profile.
Assuming that your beam settings and all the rest is fine, the scoring cards are not properly set. In particular you have to fill WHAT(4) of AUXSCORE with the name of the detector you wish the coefficients are applied to (currently you are setting WHAT(5) only in all the AUXSCORE cards).
Scoring absorbed dose (DOSE) in vacuum (USRBIN on unit 47) will give you zero in any case since there is no energy deposition. Also residual ambient dose equivalent from neutrons only (USRBIN on unit 51 and 47) will give you zero.
As final comment remember that in order to have activity from RESNUCLE scoring, the card must be associated to a DCYSCORE card.
Thank you for your reply and I apologize for the geometry error. I do not know what is goin when I open the file it gives no error and when someone else open it, it shows up with errors.
Secondly what unit in USRBIN card will be set? How can I know what I should pick? As I had picked 51 what it should be?
I wanted to calculate dose rates of neutrons in the central regional.
as long as you do not mix between output formats and scoring types and select the units that Flair lists as available, there shouldn’t be any preference on the USRBIN unit: you can organize your scorings as you find appropriate.
My main point before was that you will never be able to see residual ambient dose equivalent from neutrons. What you can do is score the prompt ambient dose equivalent from neutrons only (by removing the DCYSCORE cards associated with the USRBINs trying to score ambient dose equivalent from neutrons only) and/or residual ambient dose equivalent (without adding AUXSCORE filters).
The latter will be the residual ambient dose equivalent from the beta and gamma radiation owing to the decay of the residual nuclei produced by activation.