Which event occurs when a positron encounters an electron?

Which event occurs when a positron encounters an electron?

• A. Alpha Particle
• B. Gamma Photons
• C. Neutrinos
• D. Protons

Answer: (B)

Positron-electron annihilation converts their mass into energy carried by photons. When a positron meets an electron, the particle and its antiparticle destroy each other, and the total rest-mass energy (each has the electron’s rest mass) becomes radiation. In the simplest, typical case, two gamma-ray photons are produced, each with 511 keV, emitted in opposite directions to conserve momentum. This gamma-ray output is the hallmark of this interaction. The other options describe particles or forms of radiation that aren’t the usual products of this annihilation, so they don’t fit the process as the primary outcome.

Positron-electron annihilation converts their mass into energy carried by photons. When a positron meets an electron, the particle and its antiparticle destroy each other, and the total rest-mass energy (each has the electron’s rest mass) becomes radiation. In the simplest, typical case, two gamma-ray photons are produced, each with 511 keV, emitted in opposite directions to conserve momentum. This gamma-ray output is the hallmark of this interaction. The other options describe particles or forms of radiation that aren’t the usual products of this annihilation, so they don’t fit the process as the primary outcome.