How to get photon interaction cross section?

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Dear experts,
After reading the EM interaction course PowerPoint, I found a picture that described the photon interaction cross section.

image
image1668×942 207 KB

If I want to define a material and use 5 KeV Gaussian Photon to hit target region，how and where to get the reaction and absorption cross section data like this image? Which cards are needed to describ the photon interaction and photonuclear reaction cross section？

Looking forward to your reply sincerely!
Blu

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Dear user,

For photon interactions it is not immediate to extract cross sections from FLUKA. However, these are fairly standard quantities, which you can easily access and visualize e.g. from

https://physics.nist.gov/PhysRefData/XrayMassCoef/tab3.html

or from

https://www-nds.iaea.org/epdl97/za1to100.htm

though the latter requires processing.

Which cards are needed to describ the photon interaction and photonuclear reaction cross section？

Typically none: most photon interaction mechanisms are activated by default. Since you’re interested in simulating a 5 keV photon beam, you should lower the transport and production thresholds for photons (and electrons) in the relevant regions of your geometry. See the EMFCUT card.

Note that for photons with an energy of 5 keV, photonuclear interactions do not play a role: they matter at higher energies, typically from 5-10 MeV on. In the latter case, one requests them with a PHOTONUC card, accompanied by a LAM-BIAS card to shorten their mean free path. But again, keep in mind that photonuclear process do not matter in your problem.

As a final comment: keep in mind that FLUKA will transport photons down to 100 eV (leaving aside now the special treatment of optical photons).

With kind regards,

Cesc

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Thanks for your reply! It helps me a lot.