Gamma Ray
Definition
Pure high-energy light from the nucleus: the most penetrating common radiation, needing lead or concrete to block.
Symbol: ·
Technical definition
Gamma rays are high-energy electromagnetic photons (typically keV to MeV) emitted by nuclei transitioning from excited to lower energy states. They carry no charge or mass, penetrate deeply, and usually accompany alpha or beta decay.
Example
Cobalt-60 emits gamma rays used to sterilize medical equipment and treat cancers: the photons pass through packaging that stops particles cold.
Common confusion
Gamma rays do not make things radioactive. They are energy, not particles that stick around: irradiated food or equipment does not become a radiation source.