To simulate the interaction of gamma photons with only oxygen (O) atom

Hello! i need help in such case. I want to simulate the interaction of gamma photons with only oxygen (O) atoms in MCNP, while am using the material card for silicon dioxide (SiO2). Which card shall I use to get the photon interacted with only the oxygen component separately. Thanks for help.

In MCNP, when you want to simulate interactions with specific elements within a compound, you can use the 'MATERIAL' card with elemental fractions specified. Since you are interested in simulating interactions with oxygen atoms in silicon dioxide (SiO2), you can create a material card with only the oxygen component. Here's how you can create the MATERIAL card for simulating interactions with oxygen atoms:


MATERIAL 1 2.0
-8.0 8016.03 0.53
-8.0 8016.03 0.53

By specifying only oxygen in the material card, you can simulate interactions with oxygen atoms separately while ignoring interactions with silicon atoms.

Welcome JamalGross, but I must confess I do not understand your reply. Bits of it are very familiar but the whole is strange.

Marina123456,
There are two ways of doing this that I know and I am unsure what you need. You can remove the Silicon from your material definition in the m card, and also reduce the density in the cell definitions for every use to account for the loss of the silicon. (d*32/60).

The other way prevents photonuclear processes with silicon with the mx card. This is in MCNP6+. If, for example, your silicon dioxide is m6 in your input file and silicon-28 is the first entry;
Ought to turn photonuclear processes off for silicon-28. (Turning things off does not work for any other process). I have never tried this!

So to be clear, these two methods do different things and I don't know what that means practically, it may depend on what you are trying to do. One takes entries on the m card out, the other turns off just photonuclear processes for selected entries on m cards.