The photoelectric cross-section is influenced by which factors?

The photoelectric cross-section is primarily influenced by the energy of the incident photons and the atomic number of the medium. As photon energy increases, the likelihood of photoelectric absorption tends to decrease, while higher atomic numbers enhance the probability of this interaction due to the increased number of electrons available for absorption.

In particular, the photoelectric effect is more pronounced in materials with higher atomic numbers because these materials have a greater density of electrons in their atomic structure. Photons with energy levels close to the binding energies of the inner-shell electrons of high-Z materials are more likely to be absorbed. Thus, the relationship between photon energy and the atomic number of the medium plays a crucial role in determining the photoelectric cross-section.

Factors such as temperature, pressure, and density can influence other interactions or effects but do not have the same direct and significant impact on the photoelectric cross-section as photon energy and atomic number do.