Physical implementation for scattered radiation simulation

Physics, Transport and Magnetic Fields
1

Hello, I’m trying to simulate the scattered radiation from an X-ray tube. However, the results I obtained don’t match my experimental measurements. Is there something wrong or missing in my simulation’s implementation of particle transport and interaction? Thanks

spettro81kV(3,5Al0,1Cu).txt (4.4 KB)

Simulazione20.inp (4.9 KB)

3

Dear Andrea,

Thank you for your question. In order for me to review the input, could you provide more information on the mentioned experimental measurements? Additionally, could you attach the source routine used in the simulation?

After a first quick look, is there a specific reason on the use of the EMFRAY card?

Thanks,
Giuseppe

4

Thanks for your reply. The experimental measurements I performed were performed at the corresponding points where the dose is measured in the simulation. I’ve also attached the source routine. Thank you.

mysource_ng.f (19.0 KB)

5

As for the EMFRAY card, I initially used it to activate the compton and rayleigh but then I read that it is actually useless if I use PRECISIO, right?

6

Dear Andrea,

First thank you for the source routine.
Regarding the EMFRAY card, as you say with default PRECISIOn the Rayleigh and Compton effect are activated by default, so no need of the card. Actually, in the input the WHAT(1) = 5 which implies that only Rayleigh is activated while the binding corrections and profile function used for Compton are disabled, overwriting the DEFAULT settings.

Try to rerun your simulation without the EMFRAY card to see if this goes in the right direction with your experimental data. If not, I will have a calmer look at the input file but I will need more information on the measurements (what is being measured?) to understand which could be the relevant problem.

Thanks,
Giuseppe

7

I measured the kerma in air. My concern is that perhaps some specific card is needed to improve particle transport and interaction.

Thanks,

Andrea

8

Dear Andrea,

Thanks for providing the additional information on the experimental measurement you want to address with your simulation.

The settings required for the correct scoring of air kerma have been discussed in other posts on this forum, e.g. post1, post2.

There are different approaches to evaluate the air kerma in a FLUKA simulation. Looking at your input file, the DOSE deposited in your detectors regions is scored with USRBIN by Region (remember to normalize the results with the volume of the region). Since the kerma is the “kinetic energy released in matter” you must make sure that no kinetic energy in form of electrons and positrons can escape the scoring region.
To do so, you can set the transport cutoff for e-/e+ to a high value with EMFCUT card. It is good practice to do the same then with the PROD-CUT cutoff for e-/e+ but for this you will need to create a new AIR material for the detectors regions and apply the cut on this new material.

Hope this help,
Giuseppe