Most commonly, this refers to 511-keV photons produced by an electron interacting with a positron. These photons are frequently referred to as gamma rays, despite having their origin outside the nucleus, due to unclear distinctions between types of photon radiation.
These typically denote 511-keV photons resulting from an electron interacting with a positron. These photons are commonly termed gamma rays, even though they originate outside the nucleus and the categorization of different types of photon radiation is unclear.