During the annihilation event, what mass is converted to energy?

During an annihilation event, a positron encounters its counterpart, an electron, leading to their mutual destruction. This collision results in the conversion of their entire mass into energy, following Einstein's equation E=mc², which describes how mass can be transformed into energy.

In this event, both the positron and the electron have mass; thus, when they annihilate, their combined mass is converted to energy in the form of gamma-ray photons. This process highlights the fundamental principles of particle-antiparticle interactions, emphasizing that the mass of both particles is integral to the energy produced.

Therefore, stating that both the positron and the electron's mass is converted to energy accurately reflects the physics underlying the annihilation process, making this the correct interpretation of the event.