Fluence of photons incoming to a customized rectangular area

Dear experts,

I am currently doing my first simulations using Fluka and I have successfully defined the geometry I am interested in simulating. I am having trouble quantifying the amount of incident photons to a custom rectangular area defined through the USRBIN and EVENTBIN cards in my input tab.

I would like to plot an histogram of the energy of the incoming photons, for example by specifying the dimensions of a box similar to the process followed to complete the USRBIN card. A format similar to the “energy balance” section of the .out file resulting after simulating, but for a custom rectangular volume instead of predefined region would be ideal.

Any ideas on how can I count the incident photons along with their energy for the rectangular area of the attached screenshot?

Thanks in advance,

Hi @nnikolop,

I am a little bit confused because in the title of your post you mention energy deposition but in the body you say that you want to know the energy of the incoming photons. I will assume you want a fluence spectrum similar to that one that can be returned by USRTRACK, USRBDX or USRYIELD, but for a custom rectangular volume rather than for a given surface or a previously defined region of your geometry.

I believe there is no straightforward way of doing that using the built in scorings of FLUKA, probably one could do it via user routines but that may be overshooting. It would be easier to just redefine a little bit your geometry so you create independent regions in which standard USRTRACK scorings (for instance) can be applied and their results latter combined if needed (see red and blue regions in the image below).

Hope this helps.

Kind regards,

Dear @fogallar,

thank you for your reply! Your assumption is correct, apologies for the misleading title.

My first intuition was to redefine the geometrical regions as you indicated, but ideally I would like to define a little “window” where the photons go through and then measure the number and energy of those photons (without having to redefine the geometry every time). It seems that the built in scorings of FLUKA offer information strictly per regions.

Best regards,

Dear Nikos,

I understand. The introduction of such a window would require a (slight) modification of your geometry since it cannot be done à la USRBIN using the built-in scorings. I may add that it is not accurate to say that built-in scorings offer information strictly per region, but instead they typically profit from the geometry implementation to get the definition of those surfaces and volumes in which scoring takes place (e.g. USRBDX, USRTRACK, etc.) and sometimes not even that, as in many USRBIN types.

In case you really don’t want to modify your geometry, you can give it a try and dive in the user routines’ ocean, which offer countless possibilities. I don’t know beforehand how easy and/or optimal it would be but if you choose to do it we can continue the discussion.

Kind regards,