The probability for photoelectric absorption reaches its maximum when the gamma energy is?

The probability for photoelectric absorption is indeed highest when the gamma energy is equal to the electron binding energy. In the context of photoelectric absorption, this phenomenon occurs when a photon interacts with an atom and transfers all its energy to an electron, which is then ejected from its atomic shell.

When the gamma photon energy matches the binding energy of an electron, it maximizes the likelihood of this interaction occurring. If the energy of the gamma photon is exactly equal to the binding energy, the photon can effectively interact and provide just the right amount of energy needed to free the electron from its shell.

In cases where the gamma energy is lower than the binding energy, the probability of photoelectric absorption decreases significantly because the photon does not possess enough energy to overcome the binding forces holding the electron in place. Conversely, at higher energies, while photoelectric absorption can still occur, the likelihood begins to diminish as other interactions, such as Compton scattering and pair production (especially at very high energies), become more probable.

Thus, the maximum probability for photoelectric absorption occurs specifically when the energy of the incoming gamma photon is equal to the binding energy of the target electron. This understanding is vital in the field of medical dosimetry as it informs the design