Ionizing radiation can be directly caused by which type of interaction?

Ionizing radiation results from interactions that have enough energy to remove tightly bound electrons from atoms, thus ionizing them. Charged particle interactions are particularly capable of causing ionization because these particles, such as alpha and beta particles, carry an electric charge. Their interactions with the electrons in atoms can lead to the displacement of those electrons from their orbits.

In effect, when a charged particle passes through matter, it can transfer energy to the electrons of the atoms it encounters. If the energy transferred is sufficient, it can eject an electron, resulting in ionization. This is why charged particle interactions are recognized as a direct cause of ionizing radiation.

Uncharged particle interactions, such as those involving neutrons, can also lead to ionization but typically require the absorption of the neutron by the nucleus. This is not a direct interaction similar to that of charged particles. Magnetic field interactions primarily affect charged particles but do not cause ionization directly, and thermal radiation pertains to a different type of energy transfer that does not involve ionization events.